—AA— SiJso—Oo—
                          Technical Report
                   Aircraft  Technology  Assessment:
                  Progress in Lp.w Emissions Engine
                                 by


                            Richard Munt



                              May 1981
                               NOTICE

Technical Reports do not necessarily  represent  final  EPA decisions
or positions.  They  are  intended to present technical  analysis of
issues using  data which are  currently  available;   The  purpose in
the  release   of  such  reports  is  to  facilitate  the exchange  of
technical  information  and  to  inform  the  public  of  technical
developments   which  may form  the basis for  a  final  EPA decision,
position or regulatory action.
              Standards Development and Support Branch
                Emission Control Technology Division
            Office  of Mobile  Source Air Pollution  Control
                 Office of Air, Noise and Radiation
                U.S. Environmental Protection Agency

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                          Table  of Contents







Table of Contents	i




Summary	.1




Section I. Forward	2




Section II. Introduction	.3




Section II. Emissions Control Technology	19




Section IV. Industry Status		.39




Bibliography	123




Appendices




     A.    Control Techniques	 .A-l




     B.    Engine Data	B-l

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Summary


     This report is the third in a series whose purpose is to evaluate


the potential of various control techniques to reduce emissions, to

                                        /
assess the practicality of such techniques on commercially acceptable


engines, and to estimate the time frame in which such techniques can be


made available.  As this document is the latest and, as such, reviews


the situation after the greatest development effort has been made, it


reflects more nearly the eventual outcome of the many industry and


government programs now in progress.




     This report concludes:




     1)   NOx control for high pressure ratio engines remains in an


early stage of development with insufficient control of all four (HC,


CO, NOx and smoke) pollutants available and airworthy hardware uncertain.




     2)   Although substantial reductions in CO can be attained (>70%) ,


compliance with the proposed standard would require greater reductions
                                                                  'r '
     3)   Smoke control is well understood, but its control is compromised

somewhat by the control for HC and, especially, CO.




     4)   HC control to the level required is readily achievable only if

sector burning is permitted for some engines.




     5)   The control of HC.and CO by sector burning at idle is very

effective, but possesses unresolved problems of reliability which, in


turn, impact the economics and potentially the safety of the engines.

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                               Section I ;-

                                        /
                               FOREWORD






     On July 17, 1973,  regulations controlling the  gaseous and smoke


emissions form aircraft engines were promulgated.(3)   The fuel venting


requirement and certain specific smoke standards are  already in force;


the principal gaseous pollutant standards  originally  scheduled for 1979


have now been delayed.   The interval between the promulgation date and


the compliance date is intended to permit  the development of the requisite


technology, and in the case of retrofit, for the orderly installation of


the new hardware onto the in-use engines.






     Two previous reports have been issued (4 and 5)  which review the


status of the development of the control technology and this report,


the third in the series, constitutes an update to the second.  This


update is required to provide technical support data  for the compre-


hensive review and revision of the standards that is  now underway.(6)

                                                                  •/** :'




     Because this report is only an updating of the previous one (5), it


is abbreviated.  It attempts only to correct obsolete data and analyze


particular points relevant to the unanswered issues confronting the


revision of the standards.

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                                 Section II


                               INTRODUCTION






     Section 231 of the Clean Air Act,  as amended by Public Law 91-604,


directs the Administrator of the Environmental Protection Agency to:






     (1)  investigate emissions of air pollutants from aircraft to


determine the extent to which such emissions affect air quality and to


determine the technological feasibility of control, and






     (2)  establish regulations for the control of emissions from air-


craft or aircraft engines if such control appears warranted in the light


of the investigation referred to above.






     Furthermore, the Clean Air Act states that any such regulations can


take effect only after sufficient time has been allowed to permit the


development and application of the requisite technology.  '






     The EPA has complied with both mandates of the Clean Air Act,
                                                                        =*"

first, by publishing a report, "Aircraft Emissions:  Impact on Air


Quality and Feasibility of Control" (1) , which concluded that the


impact on air quality by aircraft was sufficient to justify control


and that such control was technologically feasible, second, by publish-


ing a report, "Assessment of Aircraft Emission Control Technology" (2),


which offered the best projection at that time of the feasibility of


control with the knox^ledge then available, and third, by promulgating

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standards limiting the emissions from aircraft engines  (3).




     In keeping with the spirit of the instructions to  determine- the

technological feasibility of control and to  the  time required  to permit

the development and application of the technology, the  EPA established

an Aircraft Technology Assessment Program for the purpose  of monitoring

the many programs for the development of the low emissions technology

for aircraft gas turbine engines.  This program  for gas turbines was

begun in July 1974 and has produced two previous reports,  "Aircraft


Technology Assessment - Interim Report on the Status of the Gas Turbine

Program, .December, 1975" (4), and "Aircraft  Technology  Assessment -

Status of the Gas Turbine Program, December, 1976"  (5).




     In March, 1978, the EPA published a Notice  of Proposed Rulemaking

(6) offering considerable revisions to the existing regulations (3).

These revisions were based upon reviews of aircraft air quality impact,

economic impact, and technology limitations, the latter being  based upon
                                                                    » •
reference 5 and additional material supplied by  the industry,  NASA, and
                                                                     **''" •
the U.S. Air Force in the intervening period between  the publication of

reference 5 and the NPRM (6).  The NPRM proposes,  among other  things, to

restrict compliance with the gaseous emissions  standards to  commercial

jet engines of sufficient size and frequency of  operation as  to warrant


their control.  This report limits itself to the assessment  of the

technology involved in  those commercial engines  which are likely to be

affected by the proposed regulations.  Emissions control technology  for


engines not affected by the proposed standards  for gaseous emissions  as

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and II-2 present the existing and proposed standards  in  both the  old,


english unit format and the new,  metric unit format.
                                            ;:

                                           /


     The classes of engines referred to in the standards were estab-


lished by the EPA to categorize the engines according to technical,


economic, and safety constraints.  In the proposed standards, the


subsonic jet classifications become less meaningful in that the gaseous


pollutant standards, like the smoke standards, are monotonic and  analytic


functions of size (thrust) and are not discontinuous  at  the class


demarcations.  For reference, the classes are listed  in  Table 11-3.





     The emissions levels permitted by the standards  are described by an


EPA parameter (EPAP) which is defined in the aircraft regulations.


Briefly, it is a measure of the total emission of a particular pollutant


produced by an engine over a typical landing-takeoff  (LTO) cycle


normalized with respect to the useful output of the engine over that


cycle.  As such, larger engines performing greater useful work are


permitted proportionally larger amounts of total emissions over smaller


engines.  The proposed standards changed the definition of EPAP by con-


sidering the useful output of the engine to be its rated power rather


than, as originally, the total work  (integrated thrust times time over


the cycle) or total engergy  (integrated power times time over the cycle)


as appropriate to each class.  As a result, the standards no longer give


implicit credit to a high idle point  (given because a high idle point


increases the useful output  term in  the demonimator in the calcultation


of the  total work based EPAP, thereby  lowering the emissions rating


relative to  the standards).

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          Original  Standard  (All  Engines)
                                                 TABLE II-l
                            Comparison Between Original and  Proposed  Standards
                                               (English Units)
                                    Newly Manufactured Engine  Standards
Proposed Standard (Commercial Only)
1979
Class
Tl
T2,3,4
T5
P2
APU




Size
0-8,000 Ibs
>8,000 Ibs
All (1980)
All
All

Class
Tl
T2.3.4
T5
P2
HC
. 1.6*
0.8*
3.9*
4.9**
0 . 4***
Original

Size
0-8,000
CO
9.4
4.3
30.1
26.8
5.0
Standard
1981
HC
Ibs
>8,000 Ibs 0.4*
All (1984
All
) 1,0*

NOx Smoke
3.7 (1)
3.0 (1)
9.0 (1)
12.9 (3)
3.0
Newly Certified
(All engines)
Size
<6,000 Ibs.
6-20,000 Ibs
>20,000 Ibs
All (1980)
All
All
Engines Standards
Proposed
1981
HC
1984 1981 ( ,
CO NOx Smoke"""
No standard Same
2.1-0-8
0.8



Standard
12.9-4.3 4.0(2) Same
4.3 4.0(2) Same
Same
Deleted Same
Deleted
(Commercial Only) c»
1984
CO NOx
No standard
3.0 3.0
7.8 5.0
No standard
Size
<6,00.0 Ibs
>6,000 Ibs
All
>2,700 HP
HC
0.4
0.4

0.8**
CO NOx
3.0 4.0-,,-,,.
3.-0 4.0
Same
6.4 8.4
(1)  SN » 331.8 (Ibs. thrust)'       (Presented graphically in original standards).
(2)  With additional allowance  for PR > 25.                                      .
(3)  SN = 300.7 (HP)"0'280
(4)  All engines, not just commercial.,
                                  •"*'''»'
*  Pounds of pollutant per 1000 pounds thrust-hour per cycle.
** Pounds of pollutant per 1000 HP-hour per cycle,
***Pounds of pollutant per 1000 HP-hour.                        '   ,

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                                                Table  II-2
                              Comparison  Between  Original  and  Proposed  Standards



(Metric Units)

Newly Manufactured Engine Standards

Class
Tl
T2,3,4
T5
P2
APU


Original Standard
1979
Size HC
0-36 KN 13.4* .
>36 KN 6.7*
.All (1980) 30.7*
All 0.26**
All 0.24***


(All Engines)

CO NOx
78.9 31.1
36.1 25.2
237.0 70.8
1.43 0.69
3.0 1.8

Newly

Smoke Size
(1) <27 KN
(1) 27-90 KN
>90 KN
(1) All (1980)
(3) All
All

Proposed Standard (Commercial Only)
1981 1984 1981 ,,,
HC CO NOx Smoke ^ '
No Standard Same
17.6-6.7 106.6-36.1 33.0(2) Same
6.7 36.1 33.0(2) Same
Same
Deleted Same
Deleted
»
VO
Certified Engine Standards
Old Standard (All Engines)

Class
Tl
T2,3,4
T5
P2

Size HC
0-36 KN
>36 KN 3.3*
All (1984) 7.8*

1981
CO
No Standard
25.0
61.0
No Standard

NOx Size
<27 KN
25.0 >27 KN
39.0 All
>2000 KW
Proposed Standard (Commercial Only)
1984
HC CO NOx
No Standard
3.3 25.0 33.0
Same
0.045** 0.34 0.45
 (1)  SN=79 (Rated Kilonewtons)   '    (Presented graphically in original standards).
 (2)  With additional allowance for. PR > 25.
                                —0 280
. (3)  SN = 277 (Rated Kilowatts)       (Presented graphically in original standards).
 (4)  All engines, not just commercial.

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                                10
                             *


                              Table II-3

                     Summary of Aircraft  Classes
Class
       Type
  Aircraft Application
  PI
  P2
  Tl
  T2
T3, T4
T5
APU
Piston engines
(exluding radials)

Turboprop engines
Small turbojet/fan
engines (0-36 KN
thrust)

Large turbojet/fan
engines intended
for subsonic
flight (greater
than 36 KN thrust)

Special classes
applying to spe-
cific engines for
the purpose of
instituting early
smoke standards

Turbojet/fan
engines intended
for supersonic
flight

Gas turbine auxil-
iary power units
Light general  aviation.
Medium to heavy  general
aviation;   some  commer—
cial  air  transport

General aviation
jet aircraft
Commercial   subsonic
transports
Commercial   subsonic
transports
SST
                                                                 . r '
Many  turbojet/turboprop
transports and business jets

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                                  11
                               •


     It is worthwhile to review the present  aircraft  emissions  situation


in order to give the reader some perspective of  the demand that the
                                            >
regulations impose on the industry.  The emissions performance  of

current production engines is presented first.   Table II-4 presents a


list of all production and development engines and for each engine, the


standards to which it must now comply, the proposed levels, the emis-

sions performance in the present production  (or  baseline)  configuration,


the manufacturer, and an estimate of  the engine's production potential,


as defined below, which crudely measures the likelihood that the manu-

facturer will attempt to comply.  In  addition, Figures 1-4 present in

graphical form the same emissions information.   The relevant standards

for these engines are, of course, the standards  for newly manufactured


engines, not those for newly certified engines as these engines are

either already certified or are expected to  be certified prior  to  the

compliance date for such engines.




     Production potential is not usually available  in hard figures.

Generally, though, the production of  all engines can  be grouped intoi ;

four categories for EPA purposes:                                    ^'.

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                                                        Table II-4
                                          Summary of Engines  and  Their  Emissions
   Class
Tl
  Engine
1979 Std.
  Production Engines;
             TFE 731-2
             TFE 731-3
             JT15D-4
             JT12A-8
             CF700-2D
             CJ610-2C
             ALF502D
             M45H
             Viper 600
  New Engines;
             RB401-07
             ATF3
             ALF502L

T2, T3, T4   1979 Std

  Production Engines:
             JT9D-7
             JT9D-70
             CF6-6D
             CF6-50C
             RB211-22B
             RB211-524
             SpeySll
  (T3)

  (T4)
Spey555

JT3D-7

JT8D-9
JT8D-17
   Size
 0-35.6 KN
              15,
              16,
              11,
              14,
              19,
              13.1
              28.9
              32.4
      KN
      KN
      KN
      KN
      KN
      KN
      KN
      KN
              16.7 KN

              24.6 KN
              22.2 KN
              33.4 KN

             >35.6 KN
205 KN
228 KN
178 KN
222 KN
187 KN
218 KN
 50.7 KN
 43,8 KN

 84.5 KN

 64.5 KN
 71.2 KN
Mfr****

AR
AR
PWAC
P&WA
GE
GE
LY
RR/SN
RR
RR
AR
LY

P&WA
P&WA
GE
GE
RR
RR
RR .
.RR
P&WA
P&WA
P.&WA''"' ...
HC
Var.
46. 6/* **
21.67*
123/*
47. I/*
97. I/*
159/*
14.8/17.0
162/16.2
156/*
1.9/*
52. 5/*
28.6/15.9
6.7
61.0/6.7
26.0/6.7
43.3/6.7
63.0/6.7
134.6/6.7
110.4/6.7
278.4/12.2
441/13.6
356/7.3
35.1/9.9
. 37.3/8.9
CO
Var.
159/*
129/*
330/*
770/*
861/*
1450/*
112/103
526/97.1
924/*
96. 9/*
153/*
136.0/95.5
36.1
98.5/36.1
87.5/36.1
96.5/36.1
119,5/36.1
172.3/36.1
145.1/36.1
435.8/70.9
420/79.8
294/39.7
124.5/55.9
112.7/49.9
NOx
Var.
43. O/*
52. 6/*
35. 8/*
29. O/*
20. 2/*
25. 2/*
28.8/33.0
31.7/33.0
16.3/*
34. 2/*
37. I/*
32.3/33.0
33.0 + Pres-
sure Corr.
61.8/33.0
54.3/33.0
65.7/33.0 "'
60.8/38.1
51,9/33.4
61.4/34.6 ...
68.1/33.0
49.5/33.0
31.0/33.0
52.2/33.0
60.1/33.0
Sk
Var.
47/38.2
51/37.6
14/41.7
/38.8
24/36.1
33/40
25/32.4
46/31.4
/37.5
/33.8
/34.7
25/32.2
Var.

4/19.3
8/18.8
16/20
13/18.9
10/19.8
12/19
66/27.9
/29.0
/24.4
23/26.2
24/25.5
Production
  (1981)
    III
    III
    III
    I
    II
    I
    IV
    III-IV
    I

    IV
    IV
    IV
    III
    III
    III
    III
    III
    I-II
    I-II
    II
    II

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                                                 Table 11-4 continued

Class
New Engine








(T4)
(TO

Engine
s :
RB410
RB432
RH21 1-535
CF34
CFM56
CF6-32
CF6-80
JT10D-4
JT8D-209
JT8D-217

Size

68.5 KN
71.2 KN
.163 KN
40.0 KN
107 KN
157 KN
213 KN
129 KN
82.3 KN
92.0 KN

M fr****

RR
RR
RR
GE
GE/SN
GE
GE
P&WA
P&WA
P&WA

HC

/19.3
78.9
32.4/6.7
53.1/15.4
12.0/6.7
48.1/6.7
55.0/6.7
/6.7
/7.5
76.7

CO

/52.2
749.9
96.6/36.1
205/85.2
79.5/36.1
102.1/36.1
736.1
736.1
741.2
736.1

NOx

733. 0
733. 0
49.0/33.0
24.9/33.0
42.8/33.0
69.1/33.0
745.2
/***
733.0
733. 0

Sk

725.8
725.5
720.5
20/30.7
722.9
721.1
719.1
721.8
724.5
723.8
Procluc I ion
(1981)

IV
IV
TV
IV
IV
IV
IV
IV
IV
IV
T5           1980 Std      All

  Production Engines;
             OLY593-610   171   KN
RR/SN
               30.7
129/30.7
                237.0
530/237
                 70.8
                Var.
70.1/70.8    32/25
II
     *     No Standard to be met
     **    xx/xx - (Actual performance)/(Proposed NME Standard)
     ***   Insufficient data to compute standard, probably 33.0.
     ****  AR = AiResearch
         PWAC = Pratt & Whitney Aircraft of Canada
         P&WA = Pratt & Whitney Aircraft
           GE » General Electric
           LY *> LycominR
           RR c Rolls Royce
           SN = SNECMA

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                                  14
                               *

Production Category                     Situation
          I              Engines already out of production;  engines
                         certain to be out of production by  the com-
                         pliance date for newly manufactured engines.

         II              Engines at or near the end of their pro-
                         duction, run by the compliance date.  The
                         few, if any, units produced after that would
                         not be sufficient to amortize the develop-
                         ment and certification cost of a low emissions
                         combustor.

        Ill              Engines in the broad middle of their pro-
                         duction run.  It is possible to amortize the
                         necessary development and certification costs
                         for emissions control over the remaining pro-
                         duction.  It is equally possible to consider
                         a cost-effective retrofit of the units pro-
                         duced prior to the compliance date; there
                         are sufficient units to amortize that develop-
                         ment and certification costs and to realize
                         air quality gains.

         IV              Engines beginning their production run
                         shortly before or after the compliance date
                         for newly manufactured engines.  There would
                         likely be insufficient engines built prior
                         to  the deadlines to warrant a retrofit
                         program.

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                                   15
             HYDROCARBON EMISSIONS VS. RATED THRUST-PRODUCTION ENGINES
     1000
      100
   HC
  EPAP
(gms/KN)
       10
                  0
                 0
                                                  G
                                    o
                                          D
                                              O
                                Proposed standard
                                 k JT15D-4
                                 $TFE731-2
                                 &TFE731-3
                                                              ALF502L
                                                            0 CF34
                                                            0 SPEY-555
                                                            G SPEY-511
                                                            X JT8D-9
                                                            &JT8D-17
                                 ^ CFM56
                                 ORB211-535
                                 O CF6-32
                                 D CF6-6
                                 QRB211-22B
                                 QRB21 1-524
                                 OCF6-50C
                                 AJT9D-70
                   50
100
150
200
250
300     350
                                 Rated  Thrust  (KN)

                                     Figure  1

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                                         16
                         CARBON MONOXIBE EMISSIONS VS.  RATED  THRUST  -
                                      PRODUCTION ENGINES
     1000
0Q
   CO
  EPAP
(gms/KN)
0
                                            Q
                                                  O
      100
                                          cr
                                                   A
                                                              JT15D-4
                                                            ATFE731-3
                                                            BkALF502D
                                                            S ALF502L
0 CF34
0 SPEY-555
OSPEY-511
X JT8D-9
DJT8D-17
ts.JT3D
K CFM56
0RB21 1-535
O CF6-32
D CF6-6
QRB211-22B
OJT9D-7
QRB211-524
OCF6-50C
AJT9D-70
                                         Proposed Standard
       10
                   50      100      150      200

                                  Rated Thrust  (KN)

                                      Figure 2
                                     250
   300
350

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                                          18
                         SMOKE EMISSIONS VS.  RATED THRUST
                                 PRODUCTION ENGINES
          70
          60
                                    k JT15D-4
                                    $TFE731-2
                                    ATFE731-3
                                                            8&ALF502D
                                                            Bl ALF502L
          50
  EPA
Smoke
Number
          40
                                    0 CF34
                                    0 SPEY-555
                                    ClSPEY-511
                                    X JT8D-9
                                    &JT8D-17
                                    fc^JTSD
                                    h CFM56
                                    ORB211-535
                                    QCF6-32
                                    D CF6-6
                                    QRB211-22B
          30
          20
                                                  Proposed  standard
                                     ORB211-524
                                     OCF6-50C
                                     AJT9D-70
0
                                                        D
          10
                                                          Q
                                                                    A
                                                              O
           o
              0
 50
   100         150

Rated Thrust (KN)

    Figure 4
200
250

-------
                                         17
                          OXIDES OF NITROGEN  EMISSIONS VS.
                           RATED THRUST -PRODUCTION: ENGINES.
         70
                                               O
                                                       D
         60
                                                             O
         50
                                                         Q
          40
  NOx
 EPAP
(gss/Kn)
            Proposed standard
          30
                       0
          20
          10
              0
50
 100          150

Rated Thrust (KN)

    Figure 3
                                   k JT15D-4
                                   $ TFE731-2
                                   ATFE731-3
                                  &kALF502D  -
                                  m ALF502L
                                  ^ K45H
                                  0 CF34
                                  0 SPEY-555
                                  Ci SPEY-511
                                  X JT8D-9
                                  DJT8D-17
                                   K CFM56
                                   ORB21 1-535
                                   O CF6-32
                                   D CF6-6
                                   QRB211-22B
                                   OJT9D-7
                                   QRB211-524
                                   O CF6-50C
                                   AJT9D-70
200
                                                                     250

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                                   19






                              Section III






                     EI4ISSIONS CONTROL TECHNOLOGY






     There are four pollutants of interest here:  the chemical species,




CO; the combination of the species NO + N02, collectively called NOx




(the latter species is the actual pollutant insofar as the formation of




smog and toxicity are concerned, but the former will eventually combine




with atomospheric D£ to form the latter at atmospheric temperature due to




equilibrium chemistry considerations); the collective group of species




of various non-oxygenated hydrocarbons, either raw fuel compounds or




compounds created by the cracking, decomposition, pyrolyzing,  or polymer-




ization of the fuel, all of which are simply called hydrocarbons or




HC.









     HC and CO are both products of and occur principally under low




power operating conditions conducive to incomplete combustion.  ~Lo\
-------
                                   20
Beyond that:, the low gas pressure and the low fuel  flow requirement lead




to poor amortization of the fuel and poor mixing with the air  which in




turn cause pockets of excessively ruch (no oxygen for burning)  or ex-




cessively lean (too weak to burn) mixture of fuel and air,  both of which




will lead to incomplete combustion and hence the emission of  unburned or




partially burned fuel (HC and CO).              .









     Smoke also is a product of incomplete combustion, but  its formation




is likely to occur at high temperature and pressure (i.e.,  high power)




if pockets of excessively rich (insufficient C^) mixture occur.  Under




this circumstance, the fuel in the pocket cannot burn (because of lack




of 62), but instead pyrolyzes in the hot, high pressure environment




laving basically microscopic carbonaceous matter, possibly  also coated




with a heavy hydrocarbon residue.









     NOx, on the other hand, is a product of an unintentional reaction.




which occurs only at high temperatures (i.e., high  power) and with ample




Q2> namely the oxidation of nitrogen either from the air itself (the




usual case) or from nitrogen bound in the -fuel. ."Unlike the others;4 bnce




fonned it cannot be consumed as it is. a final reaction.  Fortunately, at




the temperatures experienced in gas turbines, the reaction  proceeds




relatively slowly so as the gas is exhausted, the NOx levels are usually




well below equilibrium.

-------
                                  21
                               •


     The control of these pollutants  is  achieved  through various  mech-

anisms depending upon the nature of  their formation.  HC and  CO,  both


being products of incomplete combustion  are often treated  together.

However, HC consumption is fast (producing CO and H«0, plus intermediate

radicals) and occurs in the primary  zone of the combustor, whereas CO

oxidation is a relatively slow reaction  and occurs in the  intermediate

zone downstream where additional air has been added.  Thus, it becomes

possible and indeed necessary occasionally to consider the two separ-

ately.  In any case, control is achieved by enhancing the  combustion

rates, increasing the residence time in  the environment most  favorable

to combustion, or by improving the mixing of the  fuel-air  mixture to

better utilize the existing potential for reaction.  Proper fuel prep-

aration, including thorough atomization  and correct spray  distribution

is particularly useful in controlling HC, but it  may also  influence the

CO levels to a lesser degree.




     On the other hand, NOx control is achieved by mechanisms which

discourage the oxidation reactions of the fuel bound or  atmospheric  *

nitrogen.  This is achieved by avoidance of high  temperatures (>1800°K)

v/ith an ample supply of oxygen.  While theoretically simple,  such an

approach is difficult to implement practically for such will  generally

lead to operational problems (e.g.,  flame stability) or excessive low-

power emissions or possibly both.




     Smoke, while also a pollutant of incomplete  combustion like HC and

CO, arises from the presence of a different set of conditions and

-------
                                  22
                               •

requires a different means of control.   Control  is  achieved  either by

avoidance of the condition which forms  smoke (hot and  rich),  or by

careful tailoring of the airflow distribution in the aft  portion of the

combustor so that the particulate matter is consumed after it has

formed.



     Table III-l lists all the relevant control  techniques for aircraft

gas turbine engines.  The techniques are grouped into  HC  and CO control

on one hand and NOx control on the other.  Control  techniques can be

classified into four broad categories:   (1) operational control, (2)

fuel preparation, (3) airflow distribution, and  (4) staging.  Water

injection and catalysis are specialized categories  which  are not of

practical significance at this point.  A detailed description of each

control method is also presented in Appendix A.



     Each technique differs in its capacity (or  effectiveness) to

control each of the pollutants.  Similarly each  technique has its own

level of sophistication (complexity).  Beyond these factors, it is also

imperative to consider the breadth of utility of each control method"

(i.e.,  the extent of application in  the inventory of engines) and its

impact  on both the  engine and the airframe.  For this purpose, a rating •

system  is established.  The system evaluates each of the criteria

mentioned above on  a scale of one to four.  The implications of each

number  for each of  the criteria are  summarized in Table III-2.  Finally,

in Table III-3 are  the actual ratings for  the various control methods as

assessed by EPA.  In addition,  the expected effect of each  technique on

smoke  production is noted.

-------
                                         HC  and  CO Control Techniques
Control Technique

Operational
  (1) Idle speed

  (2) Air bleed


Fuel Preparation

  (3) Spray Improvement



  (4) Air blast
 (5) Air assist
 (6) Preraix
Air Flow Distribution
 (7) Advanced cooling
 (8) Rich primary*-!
                                          Basis
                         Higher pressure ratio and hotter flame.

                         Hotter flame and longer residence time.
                         Atomization and distribution of fuel to
                         eliminate excessively rich or lean spots
                         flame.

                         Atomization and distribution of fuel to
                         eliminate excessively rich or lean spots
                         in flame through use of air jets driven
                         by liner pressure difference.

                         Atomization and distribution of fuel to
                         eliminate excessively rich or lean spots
                         in flame through use of externally sup-
                         plied air jets.

                         Distribution and vaporization of fuel to
                         eliminate excessively rich or lean spots
                         in flame.
                         Prevents quenching the CO > C0£ reaction
                         at the liner wall by cooling air.

                         Hotter flame for consuming CO.
                 Comment
                         Avoids overly rich pockets which create
                         smoke and HC.
 (9)  Lean primary*-!

(10)  Delayed dilution    Longer residency at high temperature.
Staging
(11) Sector burning
                         This  approach provides,  in actuality,
                         spray improvement (3)  and a richer
                         primary (8)  at idle without affec-
                         ting  the combustor design at higher
                         p owe r s.	
Fuel penalty, noise, exessive braking.

Fuel penalty, noise, extra valving and
ducting for excess air.
Very simple if effective.  Formation of
carbon and smoke must be watched.  May
aid in NOx control  (See (15)).

Usually must be applied in conjunction
with air flow redistribution in liner
to maintain stoichiometry.


Complex external plumbing and air pump.
                                                                                                                 u>
Flashback, flame stabilization problems.
Possibly major revision of engine required
to accommodate the necessary  geometry.
Has advantages beyond that of lower
emissions.

Causes smoke formation, but has good
flame stability and relight.

Relight and stability problems.
                                                                       Pattern factor and temperature profile
                                                                       adjustment difficult.
Fuel penalty at idle due to lower tur-
bine efficiency.  Additional fuel con-
trol complexity.
* Stoichiometry refers to high power condition*  Rich at high power means near perfect  (f/a "  .067) at idle.
  Lean at high power...means..v.erv lean at idle.

-------
                                     24
     While all of these methods have potential application  in at  least


a few engines, only a few seem to be prominent at  this  point  in meeting


the proposed newly manufactured engine (NME)  standards  for  1981 and
                                            f
1984.  The first is sector burning (method 11) for HC,  CO control which


was investigated by General Electric and Rolls Royce  for use  on the GE,


CF6, and CFM56 (joint manufacture with SNECMA) engines  and  the Rolls


Royce RB211 engines.  In some cases, it alone is inadequate or faulty


and requires additional, minor modifications  to the spray or  to the

airflow distribution in order to achieve the  full  emissions control and


proper operational and mechanical performance.  In the  case of the


CFM56, an increase in the idle speed (method  1), an operational technique,
                                   V
is used.  The major performance concerns are  fuel  control maintenance


and turbine distress due to the sector burning at  idle. New  injectors,


if needed, may introduce carbon deposition problems^  The principal


advantage of sectoring is the lack of influence of the  control upon the


engine and combustor performance in flight.  The difficulty with  this


technique lies in its mechanical complexity which  could adversely affect

reliability and lead to in-flight malfunction (sectoring in flight is;


considered dangerous because of possible engine damage  or inability to  •


accelerate, depending on the power level).




     The.second major approach for HC, CO control is  selective azimuthal


burning  (method 22).  This is closely related to sector burning,  but by


dividing the  annular into a sufficient number of sectors,  the in-flight


hazards  of sector burning disappear because  there are enough burning


zones  to preserve symmetry:  in  flight operation is then acceptable.


Also,  the complexity of  the fuel control system and the need for a


failsafe mechanism  is removed.   It offers less emissions control than

-------
                                                   l;iLiny, ol CoiUrul TuchiiL
-------
                                                          Table III-3
Control Technique

Idle Speed
Air Blued
Spray Improvement

Air Blase
Air Assist

Premix-1

Advanced Cooling

Rich Primary-1*
Lean Primary-1*
Delayed Dilution
Sector Burning

Selective AZinn thai
 Burning
Quick Quench
Rich Primary-2*
Lean Primary-2*
Premix/Prevap

Fuel Staging      (1

Variable Geometry

Catalysis

Water Injection
Ref.
No.
(1)
(2)
(3)
(15)
(4)


(5)

(7)

(3)

(8)
(9)
(10)
(11)

(22)

(12)
(13)
(14)
(16)

18)

(19)

(20)

(21)
Control
Capacity
2(HC,CO)
2(HC,CO)
KHC), 2(CO)
4(NOx)
2(HC,CO)


KHC)
2(CO)
2(HC)
3(CO)
3(HC)
2(CO)
2(IIC,CO)
3(HC,CO)
3(CO)
KHC)
2(CO)
2(1IC) .
3(CO)
• 2(NOx)
3(NOx)
2(NOx)
2(HC,CO,NOx)

2(HC,CO,NOx)

2(HC,CO,NOx)

l(HC,CO,NOx)

l(NOx)
Effect
on Smoke
None
None
None
Increase
None


None

Decrease

None

Increase
Decrease

None

None


Increase
Decrease
Decrease

Increase

Decrease

?

, None?
Impact
Complexity
1
1
1-2

2


1

3

3-4

3
3
3
2

1

3
3
3
4

3-4

4

4
.
2
Application
• 1
1
4

3


3

2

2

2
4
4
2

2

2
2
1
2

2 '

2

2

2
Engine
1
1
1

1-2


3

3

1-2 .

2
, 2
4
2

1

1
2
2
3

3-4

4

4

2
Airfrarae
2
3
1

1


2

1

1

1
1
1
1

1

1
1
1
1

2

1-3

4

3
Comment




Limited to higher pressure
rates at idle. May need to
change the stoichiometry.
The external compression is a
difficult mechanical problem.

•
May receive non-emissions
benefit.



In-flight malfunction is a con-
cern.
Safe in-flight; less effective
than sector burning (11).
Low power emissions may be high
Low power emissions may be high
Flame stability questionable,
low power emissions may be high
Flashback is a concern.
May not scale down to small
engine size.
Mechanical reliability in
question.
Not readily avnilnble to
small engines. •
Not practical.

-------
                                   27
does sector burning because it is less able to optimize the stoichiometry
and because of the numerous quenching zones between several burning
zones.
                                           (
     The third major control technique- for HC, CO control is the use of
airblast nozzles, (method A) combined with airflow redistribution
(methods 7-10) to achieve the necessary stoichiometry.   This approach is
expected on the Pratt and Whitney JT8D, JT9D, and, if built, JT10D
engines.  The use of airblast nozzles alone on production type com-
bustors gave inadequate performance because of the alteration of the
stoichiometry and forced the use of additional techniques to tune the
combustor to acceptable emissions and performance (e.g., altitude
relight, durability, temperature profile, etc.).   In total, this
approach leads to changes of the stoichiometry and cooling air patterns
in flight which lead usually to increased smoke and degraded combustor
performance.

     One of the major features of the NPRM is the required retrofit of
in-service T2 and T4 class engines to achieve compliance with the .1981
newly manufactured engine levels.  Unfortunately, installation into in-
service equipment may not be quite as simple to achieve as installation
into newly manufactured equipment because of the need to replace or
modify parts  that would be properly installed new on a new engine or
aircraft.  Examples would be nozzles, fuel controls, igniters (causing
perhaps a rework of the outer casing), combustor liners, and for sector
burning, squat switches sensing  the aircraft on the ground so the fuel
control can distinguish between  flight and ground modes because  (sector
burning is  in general prohibited in flight.

-------
                                  28


     For NOx control (NME 1984^,  the leading technology is fuel staging,

(methods 17 and 18) due largely to the joint NASA-industry Experimental

Clean Combustor Program (1973-1977)  wherein, first,  single stage tech-

niques such as lean burning (method 14) we're found inadequate if em-


ployed alone, and second, fuel staging x^as investigated to resolve the

deficiencies of the single stage controls.  The latter investigation was


carried through to a technology demonstration in two test engines (not

flightworthy).  Two different approaches to fuel staging were inves-

tigated, axial staging (method 17, used on the JT9D-7) and radial

staging (method 18, used on the CF6-50).  Application or transfer of

this technology to other engines, even related ones, is not always easy,

however, and has not been pushed by the manufacturers thus far. For

instance, the radially staged combustor developed in the CF6-50, called.

the "Double Annular" can be installed on a CF6-6 only with considerable

modification to the basic engine, including the casing, although it can

be employed directly into the CF6-50 with only direct changes in the

fuel plumbing and  fuel control.  This is because the double annular

airflow requirement into the double dome calls for a dump type diffuser


from the compressor as is found on the CF6-50.  The smooth diffuser
                                                                   -,"i :
found on the CF6-6 would have to be replaced by a dump type in order to

utilize  the  double annular  idea  (Figure 5).  Similarly, use of the

double annular concept in the CFM56 is questionable because its much

smaller  size  (Figure 6)  does not  lend  itself readily to staging in-

volving physical separation of the zones.   This separation increases

considerably  the S/V ratio  and reduces simultaneously  the residence


time.  When  combined with the overall  smaller geometry of a smaller


engine, both  factors adversely impact  the HC and CO emissions.

-------
      SIZE COMPARISON BETWEEN THE CFM56  AND Ci'6-6 COMllUSTOUS
                                           -.
                                  .,,^_../" ~~^—*~~~—*jii__'	"'"^"^'•''•'-'^v/l-^-^''"r



CFM56
CF6-6
                                Figure 6

-------
                             29
COMPARISON OF DIFFUSERS BElWEEN THE CF6-6 AND CF6-50 ENGINES
Diffuser
Diffuser
             Double Annular Corabustor in CF6-50




                          Figure 5

-------
                                  31
     Rolls Royce did not benefit in this  technology  development  by




direct association with the program and consequently has  not  yet engine




tested a fuel staged combustor in an RB211.,S  Its  recent investigations




have, however, explored the benefits of both radial  and axial staging




and it has leaned in favor of the former because  of  the packaging con-




straints imposed by the relatively short combustors  of the R3211 family




(a similar situation to the CF6).









     NOx control by fuel staging is in the exploratory development stage




and is not yet ready for final development into specific  engines for




certification of airworthiness.  Developmental problems for which solu-




tions have not yet been identified are (1) the achieving  of all four




emissions goals simultaneously,  (2) insufficient cooling  air  for ac-




ceptable durability performance, and (3) engine performance degradation,




notably transient response.  Other shortcomings in the concepts at




present are considered normal for this stage of development and would be




expected to be resolved in due course.









     As indicated in the preceding paragraphs, manufacturers  have often




found it necessary  to combine more than one emission control  concept.




This is, in fact, the rule rather than the exception.  Such compounding




may be necessary because of  the  inadequacy of a single control concept




to sufficiently reduce  the emissions, or it may be necessary  because  of




combustor performance deficiencies brought about by the use of a  single




control scheme.  In the former  category would be the combining of




airblast nozzles with liner  airflow redistribution.   In the latter would

-------
                                     32


                              •

be the utilization of fuel staging with separate  lean and rich primary


zones.  Often the rationale is a combination of the two.



                                          f           •

     The adding on of one control scheme upon another is  not guaranteed


to produce a geometric compounding of results;  there may  be, in fact, no


improvement at all despite the fact that each separately  may be quite


effective.  For example, while redesigned nozzles and sector burning may
                                               i

individually produce emissions reductions, the first because of improved


atomization, the second because of atomization and stoichiometry, their


joint use is likely to be no better than the sector burning alone be-


cause that in itself already accomplishes that which the  redesigned


nozzles purports to do  (i.e., improve atomization).





     On the other hand, complementary forms of control may achieve


synergetic results:  redesigned nozzles combined v;ith advanced cooling


techniques may together serve  to reduce emissions that result from dif-


ferent mechanisms of formation  (i.e., poor atomization and mixing .in the


primary vs. wall quenching on  the  liner).  It is also possible thatj the


use  of only one control will aggravate a condition which will lead &Q


the  formation of more pollutants and hence will require two or more


control schemes to balance each other.  A significant example of this


situation is the use of airblast nozzles which while providing better


fuel atomization and mixing, also  leans the primary zone stoichiometry


by its own airflow.  This may  result in an excessively lean mixture  so


that an airflow redistribution to  richen  the primary is also required.


Together,  the two approaches provide improved atomization, better


mixing, and optimal stoichiometry.  Similarly, the conflicting require-


ments of  NOx control and HC, CO control require a combination of control

-------
                                     33
techniques,  itsost notably through fuel staging  in which  the  two separate




portions utilize control techniques applicable to  the particular  pol-




lutants which are expected from them.









     The above discussion makes repeated reference to the conflict




between emissions and combustor performance and this reference is con-




tinued in Section IV.  Therefore, a brief explanation of combustor




performance is appropriate.     The criteria by which combustor per-




formance is judged are related to both economic and safety  consider-




ations.  The economic criteria are created by  the  users while the safety




criteria are dictated by the users, the FAA, and common sense. Com-




bustor performance itself is two-fold:  operational and mechanical.









     Operational performance is measured primarily by ground ignition




and engine acceleration, altitude relight, and flame  stability (com-




bustor response to engine transients, either intentional or accidental).




Mechanical performance standards are largely determined by economic con-




siderations and the  principal criteria are durability,  coking, and




carbon deposition.   The first two are obviously considerations for the




cost of  maintaining the system, but the third may not  be so apparent.




Carbon deposition impacts the engine durability and hence maintenance




cost first  through the  turbine erosion which occurs when particles are




broken off  the combustor or nozzle surface and sent downstream, and,




second, by  its adverse  effect on the combustor cooling  (due to a  change




in  the radiative emissivity).

-------
                                    34
     Table III-4 lists the best emissions performance  that  has  been




achieved in each engine.   These data are also presented graphically in




Figures 7-9.  However, in a few cases the ca~a nay  represent  combustor




rig data rather than engine data (e.g.,  CJ&10) or possibly  educated




extrapolation from data of a related engine (e.g.,  RB211-535  figures




originated from RB211-22B data).  Most importantly,  though, the data may




be iron a configuration which has been found unflightworthy (e.g.  Spey




511) or otherwise projected as unsafe.  The purpose of this table is




nerely to present in concise form the kind of control  that  is achievable




by the control methods listed.  The standards proposed for  each engine




are presented also as a point of comparison.  A more accurate interpre-




tation of the situation of emissions reduction is to be found in Section




IV, Industry Status.

-------
             Tablu I!1-4
Summary of Boot Kmius ions Performance
Claag Engine
Tl Production Engine!
TFK731-2
TTK731-3
JTI5D-4
JT 1 2 A -8
CK 700-20
CJ6IO-2C
A1.K502U
M45II

Viper600
New F,nf»ine8

ALF502L

Size

15.5 KN
16.5 KN
11.1 KN
1 / t VM
IH * / KN
l'J.2 KN
13.1 KN
28.9 KN
32.4 KN

16.7 KN
rt/ L i»ij
*H . D KN
fj 1 tf ll
ii . i KJf
33.4 KN

IIC CO

4.5/* 59. 8/*
	 No Data 	
1.4/* 10U/*
— -— -~**No Tech no 1 o^y-~
14. 7/* 861/*
23. 4/* 1440/*
14.8/17.0 112.4/103
30.1/10.2 170/97.1

NOx

50. 5/*

47. 11*
20. 2/*
25. 2/*
' 28.8/33.0
37.0/33.0

Sk

/38
/38
/42
/36
/40
/32.4
12/31

Date of
Availability






Cert if ied
Jan. 1979

Comment

Kxturii.il air itthiht.

Primary/ injector modi 1 icJit ion.
Nozzle mod i f i rat ion .
Nuzzle moiliri(;il ion.
A t rb 1 ,-ist nozz 1 e/ 1 i..'ij»"r . pr it»i;tr y .
Adv.'ntced cooliiii*. (illit. liiuwti
rint;).
-------No Technology—— -


9.1/15.9 92.2/95.5



35.4/33.0



/31.2

Tnrt IQ7Q
Jun • iyl7
1979


Advanced cool ing*, (dbl . blown
rinp.)
Combustor same as 5021). Idle
at 10.73:. NOx hit-.li.
T2, T3, Production Engine*
T4
JT9D-7


JT9D-70
CF6-6D
CF6-50C



RB211-22B

RD211-524

Spey 511



Spey 555



JT3D-7


JT8D-17

New Knitincs
RI14 1 0
RB432
RB211-535


CF34
CFH56
CF6-32
CF6-80
JT10D-4
JT8D-209
JT8D-217
ti Production Engine*
OLY593-610

205.3 KN


228 KN
178 KN
224 KN



187 KN

218 KN

50.7 KN



43.8 KN



84,5 KN

Me VU
\ * J f*rt
71,2 KN

j> n c uu
68.3 KN
71.2 KN
163 KN


40 KN
107 KN
157 KN
213 KN
129 KN
82 KN
of vtt
92 KN
171 KN

4.5/6.7 24.6/36.1
2.1/6.7 30.2/36.1

4.0/6.7 20.0/36.1
1.8/6.7 28.3/36.1
1.0/6.7 37.1/36.1

2.4/6.7 49.8/36.1

4.2/6.7 28.8/36.1

3.1/6.7 22.4/36.1

23. O/ 162/



36.1/12.2 186/79.8



158/— 232/—


7.6/8.9 49.4/49.9
1.6/8.9 83.1/49.9



8.9/6.7 54.7/36.1

2.5/6.7 '67.5/36.1
12.7/14.4 ' 80.0/85.2
0.-9/6.7 42.0/36.1
2.0/6.7 29.8/36.1
2.0/6.7 /36.1
	 .-—No Data—--
2.2/7.5 33.6/41.2

<30.7/30.7 <237/237

47. 4/ —
26.2/33.0

4H.5/ —
65.7/~
60. 8/~

44.7/38.7

64.0/--

70. 2/—

68. 2/



55. 2/—



53. O/--


68. 4/—
41.0/33.0



, 51. 3/~

30.3/33.0
27.0/33.0
43.5/—
64. I/--
/
...._
54. 9/—

<70.8/70.

<20/19.3.
30/19.3

<10/18.8
16/20.0
/18.9

/18.9

/19.8

/18.7

/



/29.0



13.3/25.0


/25.5
27/25.5


/21.2

/21.2
20/29.7
/22.9
/21
/19.1

15/24.5

8 725








1986-87





Approocli aban-
doned, perfor-
mance not ac-
ceptable
Approach aban-
doned, perfor-
mance not ac-
ceptable
Jan. 1981










Date of Cert.
Date of Cert.
Date of Cert,

Date of Cert. •
.
Jan. 1980

Aerating nozzle/rich primary.
Low NOx combuntor (Vorhix
«t ;IK itt^) .
Aer;itinn nozy.l e/ r i ''h primary
Sect nr burninj* .
Sector btirn inj'./domi1 nnd nozzle
mod i f i cat ion.
Low NOx cninhiirit or ((>!'}. Anun-
Inr)
Sector burnini; »ml riili pri-
m.iry ( I'luiKe II).
Sec-tor burniiif' .'old ri«h pri-
m.'iry ( Ph;u;e II).
Ueflex airi>pr/iy.



Piloted airblast.



Leaner primary & nirblast;
intended for T3 smoke retro-
fit only.
Aernt ini> nnzzli'/rich primary.
Lox NOx combublor (Vorbix).


Sector burninp, and rich primnrv
(1'lll.SU 11).
Rich primary .iml qui'^ qtn.-nch.
Sector burn inc..
Sector burning at 61 idle.
Sector burnfiiK,
Sector burning,

Aerating noizle/ricti primary.

Blown rlni{.

-------
                                          36
                     HYDROCARBON EMISSIONS VS. RATED THRUST -
                               LOW EMISSIONS ENGINES
      100
                                                             k JT15D-4
                                                             £ TFE731-2
                                                             6TFE731-3
                                                             S&ALF502D •
                                                             a ALF502L
                                                             ^ M45H
                                                             0 CF34
                                                             0 SPEY-555
                                                             O SPEY-511
                                                             X JT8D-9
                                                             &JT8D-17
    HC
  EPAP
(gms/KN)
        10
                                         h CFM56
                                         • RB211-535
                                         O CF6-32
                                         D CF6-6
                                         QRB211-22B
                                         OJT9D-7
                                         ORB211-524
                                         O CF6-50C
                                         AJT9D-70
                                        Proposed standard
                                                O
                                             Q
                                                     A
                                      O
                                            D
           0
50
100
150
200
                                                    -e-
250
300
350
                                  Rated Thrust  (KN)

                                      Figure 7

-------
                                         37
                    CARBON MONOXIDE EMISSIONS  VS.  RATED THRUST  -
                                LOW EMISSIONS  ENGINES
     1000
                                                               JT15D-4
                                                               TFE731-2
                                                               TFE731-3
                                                             &ALF502D
                                                             HALF502L
                                                             0 CF34
                                                             0 SPEY-555
                                                             Ci SPEY-511
                                                             X JT8D-9  .
                                                             &JT8D-17
   CO
  E?AP
(gts/KN)
      100
0
      h CFM56
      • RB21 1-535
      O CF6-32
      D CF6-6
      QRB211-22B
      O-JT9D-7
      QRB211-524
      O CF6-50C
      AJT9D-70
                                                   Q
                                                      Proposed standard
                                    O
                                               O
                                                   A
       10
          0
  50      100       150      200

                Rated Thrust (KN)

                    Figure 8
250
300
350

-------
                                          38
                          OXIDES OF NITROGEN EMISSIONS VS.
                         RATED THRUST-LOW EMISSIONS ENGINES
          70
          60
          50
          40
   NOx
  EPAP
(gns/KN)
          30
          20
          10
                       0
                         50
 L JT15D-4
 $ TFE731-2
 &TFE731-3
^ CF700
 SkALF502D •
 03 ALF502J.
                                                 DkJT8D-17
0 CF34
0 SPEY-555
& SPEY-511
X JT8D-9
b CFM56
0RB211-535
OCF6-32
D CF6-6
QRB211-22B
OJT9D-7
QRB211-524
O CF6-50C
AJT9D-70
     Proposed standard
                                                                   O
                                                              O
   100         150

 Rated Thrust (KN)

     Figure 9
           200
250

-------
                                    39
                                 *

                              Section IV

                            INDUSTRY STATUS




     The discussion in this section is limited to those engines which

will be affected by the standards, namely those in commercial service

with a rated thrust of 27KN or greater.  Engines in this category are

limited to those made by only four manufacturers, General Electric,

Pratt and Whitney Aircraft, and Rolls Royce (certain engines involve

joint ventures with other manufacturers) and possibly Avco Lycoming.

Each manufacturer and its products will be treated separately.




     1.   General Electric




     General Electric is a large diverse manufacturing company in the

United States.  Its commercial aircraft engine operations are located in

Cincinnati, Ohio (CF6, CFM56) and in Lynn, Mass. (CF34, CF700, CJ610).

The CFM56 is a joint venture with SNECMA of France, the core of which is

based upon the military F101 engine designed for the B-l bomber.  In   " '

addition to these civil engines, GE makes a number of military vari-   f'

eties, some of which are essentially the same as .the civil engines.  A

summary of the company's civil engines is presented in Table IV-1.




Suianary of Research and Development Effort CF6, CFM56
 CF6
     General Electric's NOx  control effort has centered largely around

-------
                                                Table IV-1
Engine    Class    Thrust
CF6-50
CF6-6
CF6-32
CF6-80
CFM56
CF34 .
CF700
CJ610
BPR
PR
T2
T2
T2
T2
T2
T2
Tl
Tl
224 KN
175 KN
145 KN
213 KN
107 KN
40 KN
20 KN
13 KN
4.4
5.9
4.8
	
5.9
6.0
1.9
0
29.8
24.5
24.4
32.0
25.6
19.5
6.6
6.8
                                         General Electric Engines
Combustor      Application

    A        DC-10,B747,A300
    A             DC-10
    A        Potentially B757
    A     B767, A310
    A     Possibly B707.A300B11
    A              None
    A     Falcon 20,Sableliner75A
    A         Learjet 24/25
Cert.
Date



1981


A

Number
Delivered


0
0
0
0


Product ion
Category
III
III
IV
IV
IV
IV
II
I
                                                PROSPECTUS
                                                          Prospects of Meeting;
Engine
CF6-50
CF6-6
CF6-32
CF6-80
CFM56
CF34 .
1981 1984

poor*
poor
poor*
marginal
poor*
marginal
marginal
marginal
marginal
fair
good
good
' Emissions
HC CO

X X
X
X X
X
X X
X
X
X
X
X

*- -• : •
Performance
NOx Sk


X

X

X

X




Operational
Performance


X

X

X

X




Mechanical
Performance


X

X

X

X




•Time

X ,
X
X
X
X
X

X

X


*    Assuming sector burning is not used,

-------
                                  41
                               •






the NASA Experimental Clean Combustor Program (ECCP).   This  portion of




the jointly funded program with NASA  utilized the CF&-50 engine as a




testbed, but it should be considered  as a technology  demonstration




program having application to annular combustors in general, within




geometric limitations.  The ECCP  was  divided into three phases, the




first being a screening of several concepts involving prefixing, air-




blast, lean primary burning, and  fuel staging incorporating  some or all




of the previous concepts.  The second phase involved  refinement of




selected concepts and the third phase was an engine test of  the best.




The program is now completed (except  for documentation of the final




engine testing).  The final concept developed by GE is termed the




double annular combustor and is shown in Figure 10.  It is a radial fuel




staging concept and is particularly well suited to GE engines which have




short annular combustors and are, therefore,.less amenable to the




physically, longer axial staging concept (e.g., the Pratt and Whitney




JT9D Vorbix).  A detailed description of how such staging reduces




emissions given in Section III and Appendix A.









     The engine test  in phase III of the ECCP served as both a proof of




concept demonstration (with partial success) and, in fact, went one step




further by attempting to provide flightworthy quality hardware in the




demonstration.  Unfortunately, but perhaps predictably, this was at




least partially responsible for the failure  of the system to live up to




the expectations of phase II.  The specific  revisions to the engine




hardware for phase III included a modified inner liner, revised liner




cooling, additional allowance for thermal expansion, and changes in  the

-------
DOUBLE ANNULAR COMlHUiTOR CONFIGURED FOR Till' CFO-^O
                                              \J  PILOT STAGE



                                              2)  MAIN STAGE
                                                                                   ts3
                    Figure 10

-------
                                  43
                               •



connections between liner parts.   Together these changes led to a more


durable combustor, but one which also suffered from an inferior fuel


injection pattern and degraded mixing which manifested itself through a


deteriorated emissions performance.   However,  a realistic development


program must eventually address the durability problem and as the phase


II results suggested that the emissions were successfully under control,


turning attention to durability was a reasonable next step.






     Current problems with the double annular combustor as presently


configured in the -50 are:  (1) high CO - due largely to the hardware


changes incorporated in the engine test to aid durability (the Phase II


rig version had acceptable CO); (2) high NOx -  a definite problem


although GE sees some room for improvement; (3) high smoke — due to


inadequate mixing in the robust version xvhich if eliminated would bring


the NOx down, too (the Phase II rig version had acceptable smoke); (4)


durability - mostly an.unknown but the uncooled centerbody is definitely


subjected to a severe environment and the lean front end (primary)


leaves less cooling air for the liner (see Table IV-2); (5) temperature

                                                                     •/'*" "•
profile - the high air demand of the double burner dome (as seen in


Table IV-2) to run lean in the main burner plus have a separate pilot


burner plus the cooling air requirement for the liner leaves only 2% of


the air left to trim T, instead of the usual 20%-30%, and impacts the


turbine durability);  (6) flow control - an altitude compensating control


is necessary to distinquish at equal flow rates between high altitude


cruise  (both annuli burning) and approach  (pilot only).  Any change in


the configuration to  improve upon these problems must retain the other

-------
                                  44


expected operational performance levels such as  acceleration,  relight at

altitude and so forth.



     On the positive side of the ledger, however,  ground  start,  altitude

relight, lean blowout,  pressure loss, carbon deposition,  cruise  com-

bustion efficiency, liner wall temperature,  and  engine acceleration all

meet or appear to meet engine requirements.   The exit temperature pat-

tern, although out of specification, could be at least partially due to

the high fuel-air ratio required by the "worn" test engine.   This is

presumed because temperature pattern exhibited a hot hub  consistent with

an over fueling (by 17%) of the main stage inner annulus.  Sufficient

refinement of the pattern may then be possible despite the shortage of

dilution air (Table IV-2) with which to work (the temperature profile

can also be affected by manipulation of the airflow pattern within the

primary zone although this may be anticipated to be deleterious  to

emissions).  Finally, it should be observed that despite  the excess fuel

no liner hot spots or carbon deposition was observed.
                                Table IV-2

                         CF6 Airflow Distribution
Dome:


Cooling:

Dilution:
CF6-50 Standard

     35%


     32%

     33%*
CF6-50 Double Annular

     Primary 25%"\
     Main    51% J

             22%

              2%
76%
 *Not  all of  this  is required  for temperature trimming.  The CFM56,
  for  instance,  uses about  20%.

-------
                                  45
                               •



     Double annular staging apparently  requires  single  stage  operation


at approach as well as at ground idle (both stages  at high power)  in


order to lower the CO (the use of only  one stage creates  better  at-


onization and nore concentrated burning).   This  creates the additional


need to ascertain in detail the staging behavior in flight, both in


normal operation and with malfunctioning in the  fuel control  logic or in


the valving.  The single stage operation at approach does contribute to


the high KOx level which is of concern  (about 18% of the  cycle NOx


arises in the approach mode).





     The present design allows no room  for significant  simplification in


teras of liner configuration,  number of fuel nozzles, and manifolding.


Hence, it may be expected that cost estimates based upon the  present


configuration are realistic.





     A double annular configuration has been designed for the CF6-6


engine (Figure 11) and although differing in detail from the  CF6-50


configuration, it is in essence the same, working on the same principl'e


and with similar design parameters.  Certain problems have been iden-'


tified with the use of the double annular concept in the CF6-6,  however.


Presently, the -6 has a smooth diffuser which is incompatible with the


flow pattern needs of the wide dome of the double annular combustor;


hence, a step or dump diffuser, similar to that employed in the -50 is


needed (scaled to size, of course).  Because the diffuser and casing are


integral (compressor rear frame), this change would necessitate a major


redesign of that high pressure shell, at a cost .estimated by.;GE in the


neighborhood of 40 million dollars, if pursued.   The ensuing changes in .

-------
                                  46
                               •



the external dimensions, although not large,  would  impact  the nacelle


packaging of the components external to the engine  casing,  such  as  the


fuel manifold, compressor bleed, etc.  Another  problem  is  that the  large


fuel nozzles required by the double annular concept do  not fit readily


in the -6 which now uses smaller nozzles.   Beyond requiring larger  holes


in the casing, the larger nozzles have a significant effect on the. flow


pattern and pressure drop across the combustor.  For these reasons,


direct scaling of the -50 design is not considered  feasible, and addi-


tional development work specific to the -6 would therefore be necessary,


even if all the deficiencies identified in the -50  program were  remedied.






     The CF6-32 is a clipped fan CF6-6 having the same  core and  hence


the same combustor, and although operating at different conditions, it


is expected that the -6 design will be adequate in the  -32. GE  has not


yet committed to testing the -6/32 configuration even in combustor rigs.






     GE is actively continuing  its double annular technology develop-


ment, though, in the NASA Energy Efficient  Engine (E ) Program.  This
                                                                    ;."*i "

is also a technology demonstration program (not a prototype development


effort) in which it is  hoped to demonstrate more efficient components


and engine cycles on an engine  assembled from  these new components and


sized to  the  110-130KN  range.   Thus,  this development does not directly


relate to the CF6 development and,  in fact,  the GE combustor configur-


ation and size  are more related to  the CFM56.  Nonetheless, the tech-


nology improvements should  be relevant.  Principal advances to be  ex-


plored are  (1)  single  fuel  injector  stem per nozzle pair,  (2)  cooled

-------
                47
COMPARISON BETWEEN PRODUCTION AND
 LOW NOx COMBUSTORS IN THE CF6-6
           Production
         Double Annular
            Figure 11

-------
centerbody (separating the stages),  (3)  advanced  cooling,  and (4)



better NOx and smoke control.   The best  airflow pattern refinements for



emissions and operational performance will be sought.







     GE has also pursued independent investigation of  simpler concepts



through their IR&D funding.  These concepts include compressor bleed,



advanced idle, sector burning, nozzle modification, and liner redesign



(airflow redistribution).  These approaches are directed at HC and CO



control only and despite their relative simplicity, they can be quite



effective.  Much of the preliminary investigation was  done on the



developmental CFM56 (F101) as the early CF6 effort was devoted prin-



cipally to the NASA ECCP.







     GE elected to continue development of the sector burning concept in



the CF6 for the proposed 1981 requirement.  The governing principles



behind the sector burning  concept are described in Section III and



Appendix A.  Although sector burning creates a fuel control problem with



its staging at idle, a very desirable feature is  that during proper  .



operation, there is no effect of the emissions control on the combustor
                                                                     -."*« ;


in flight so  concerns about operational and mechanical performance are



considerably  reduced.  Used alone,  this method is sufficient only  in the



CF6-6 and probably CF6-32  engines.  The CF6-50 and -80 would still



suffer from high CO because of  their very  short combustors.  CO, in



fact, tends to  be a  problem  in all of the GE engines due to their short



combustor designs which  allow inadequate time for its oxidation to C0_.



A short  combustor  is  pursued  because  it.requires less liner  cooling  air



 (hence more is  available for  radial, temperature distribution trimming



and  for  turbine cooling) and  it creates a  shorter and hence  lighter  engine.

-------
The CF6-50, in addition to the sector burning,  requires new fuel  nozzles




to improve the mixing and local stoichiometry in the  primary.  The new




nozzles insure that at idle all the fuel is being injected through only




the primary orifice in each of the pressure-atomizing duplex nozzles,




thus providing greater atomization.   From existing data this solution




gives the CF6-50 a 15% margin in CO emissions,  but because of  the antici-




pated engine-to-engine variability,  there may still be compliance problems.




Further reductions could be achieved by increasing the idle power, but




as this is an engine already in use, such a procedure would run afoul




commitments to the airframe manufacturers and would particularly  be




difficult to implement in a retrofit program (proposed in-use  compliance




requirement by 1985).









     A major concern with sector burning is the effect of the  asymmetric




thermal loading at idle when the fuel is sectored in  the  annulus.  The




most favorable fuel distribution with regard to emissions is to have a




single large sector off and the remaining sector on (here 180  on and




180  off).  This, however, is the most adverse for the turbine stator




and guide vanes.  Furthermore, the frame distortion may cause  increased




wear on the rotor blades with subsequent efficiency losses at  all power




nodes.  In addition, the asymmetric heat imput reduces the mechanical




efficiency of the turbine which leads to a fuel economy penalty  during




the sectoring mode.









     The fuel control and delivery system also has additional complexity




(see Figure 12), but this is outside the hot section  and  is thus  easier

-------
                              50
                FUEL CONTROL FOR SECTOR BURNING
Staging Valve
       L,
                        ".
                          x 1
                        IA'
                                 n
 ii
ITT
Fuel
               o ooi
                                                       Manifolds
                                             ir
                          j{  Logic
                          h Signal
                           Figure 12

-------
          '                             51

                                •
to handle.  The fuel control must be able to sector when required,  must

distinguish between in-flight idle and ground idle, and must  be  fail-

safe (any failure will cause the system to revert  to full annular

operation at the proper flow rate).   The failsafe  mechanism is crucial

to the safety of the system as inadvertent sectoring in flight might

lead to engine damage or inability to accelerate,  depending on the  power

level at the time.




     Sector burning development ceased in 1979,  however, when GE was

informed by its customers that, in their opinion,  sector burning's

potential hazards and idle fuel penalty rendered it unacceptable.  GE

has since reverted to a selective azimuthal burning arrangement. This

involves selective nozzle firing at idle, but instead of a single,  large

sector being turned off (eg, 180 sequential degrees), this concept  might

turn off, say, 120 degrees distributed over five individual sectors [for

instance, if there are 30 fuel nozzles, at idle, a pattern of 4  on  and 2

off would be repeated 5 times].  This arrangement permits acceleration

in flight and avoids the hazards of asymmetrical thermal loading on the

guide vanes and stators which could damage the engine.  Thus, there is

no potential in-flight safety problem and the system is used for both "

flight and ground idle.  However, the emissions performance is degraded

somewhat.




     A new dome is to be incorporated, partly to help emissions, but

largely  to improve pre-existing deficiencies in the mechanical performance

of  the original combustor.  This dome is a version of the new design

that was developed for the new CF6-80 engine and hence represents little

-------
                                     52
additional development effort or expense.
CF6-80
     The CF6-80 is a new engine family based upon the best technology of




the CF6-50, but incorporating many new features.  It constitutes a new




fanily because in its conception total design flexibility was permitted.




As a consequence, major changes in the hardware are:









     (1)  Aerodynamically superior fan blades (same diameter),









     (2)  15 cm reduction in length of diffuser,









     (3)  8 cm reduction in combustor length and replacement of the




          conventional brazed ring type with a new machined rolled-ring




          type,









     (4)  Elimination of the turbine midframe (18 cm),               i  •




                                                                     •* •




     (5)  New low pressure turbine.









The  overall length  is shortened by 4 cm,  the engine lightened by  130-




230  kg, and cruise  specific fuel consumption is improved by 6% over  the




CF6-50.









     The  new combustor incorporates a revised airflow pattern to  improve




burner  life and  performance.  Less cooling  air  is admitted at the dome

-------
                                       53

which permits (1) a richer front end (and hence better relight)  and (2)

more cooling air for the aft liner (and hence a cooler lir.a) .   A longer

version of this improved combustor will be used in nev CF&-59s and may

be also available as a retrofit option.  In response to airline desires,

GE will make every effort to avoid the use of sector burning as a control

technique, but the shorter length will work to the disadvantage of CO

control; on the other hand, it will work to the advantage of NOx control

and may help to mitigate the adverse effect of the very high pressure

ratio.



     The anticipated control scheme is selective azimuthal burning which

was discussed in the CF6-50 section.  The necessity for in-flight operation

requires a minimum of 5 sectors in order to preserve sufficient symmetry. .

With 30 fuel nozzles, this means 4 on - 2 off, 5 times around-  With

this operation, altitude relight is marginal; however, a 2 on - 1 off

arrangement, 10 times around (ie, 10 sectors), resolves this difficulty,

but at a cost of further reduced emissions effectiveness.  Table IV-3

summarizes the known abilities of the different concepts as applied to

the CF6-80.                                                          "" '



                              Table IV-3

                   performance of Control Techniques

   Control                                      HC EPAP
 Sector Burning
   15 on - 15 off, once around                      1

 Sective azimuthal burning
   4 on -2 off, 5 times around*                    6

   2 on -  1 off, 10  times around-                  12

 *  possible for in-flight use

-------
                                       54
     Little information about NOx control.is  known  at  this  time.   However,


it is apparent that the small available volume will make  the incorporation


of staged systems quite difficult.   Yet, because  of the small size,

                                            =
cooling air requirements are reduced and more air is  therefore available


to the two stages of a double annular combustor with,  perhaps, sufficient


air left for temperature profile tailoring:   this may  make  the staged


combustor more viable in this application,  if it  can be fitted in.
CFM56
     This engine, designed jointly with SNECMA of France,  has a core


which is derived from the military F101 engine.   The cycle of the hot


core is roughly that of the military engine,  but the initial combustor


intended for the military was not suitable for commercial  use and con-


sequently a program for the development of a proper combustor was


established.  Much of the emissions development was done on this later


model combustor (the PV combustor) which is shown in Figure 13.





     In addition to a design effort to configure the double annular
                                                                     •-•v •

concept to this engine (Figure 14), GE has pursued other avenues of NOx


control during the development of this engine through IR&D funding.


This approach attempted to make use of the short configuration of the


combustor which tended to lox^er NOx levels anyway (short residence


time).  Because of the short design, special effort had been made to


achieve proper combustion in a very short distance by excellent fuel


preparation (atomization and evaporation) and mixing with the air.  This


feature, aided if necessary by sector burning at idle, could be suf-


ficient to permit the application of a quick quench approach to NOx

-------
i'V C
        (CFMr>6)
Figure  13

-------
    UOUIJ1..K ANNULAR  CUNK l.CUKATI.UN RM CKM!)6
(SHOWN HERE, ENERGY EFFICIENT ENGINE PROPOSAL)
                                                                                       C^
                   Figure 14

-------
                                    57






control (see Section III and Appendix A)  and yet  have  acceptable  low




power emissions.   The advantage of such an approach  is first mechanical




simplicity versus, e.g., staging,  and second, .inherent flame stability




compared with lean flame NOx control.  . As explained  in Appendix A,




however, the drawback to quick quenching is that  while it  quenches  the




^2  -*•  NO reaction (a benefit), it also at idle quenches the CO    -»•




CO. reaction and possibly also the oxidation of HC (a  detriment).   Very




quick combustion as occurs in an advanced combustor  may bypass  that




difficulty.  Rig testing in an F101 testbed with  the original combustor




demonstrated a 30% reduction in the NOx El.  Later testing in.the new




combustor, however, was not as successful, and  further exploration  was




shelved.  Development of a double annular combustor  for this engine has




not proceeded beyond the design study because of  the need to resolve the




developmental problems of the concept on the parent  engine (CF6-50)
     HC, CO control by sector burning and selective azimuthal burning




 (SAB) was investigated early in the F101 combustor rig.   The new PV




 conbustor with SAB had better emissions than the original combustor with




 SAB; however, its operational performance was degraded considerably and




 the CO was still too high.  Specifically, the pattern factor and altitude




 relight were deficient and the CO was twice the standard.  In addition,




 the liner cooling requirement was not met.  A subsequent program to




 remedy these deficiencies through variations in the venturi configuration




 of the airblast nozzles, the fuel spray angle, the primary stoichiometry,




 and the manner of dilution air entry (the degree of penetration) was




 undertaken.  There developed' a tradeoff situation between relight capa-




 bility on one hand and CO and smoke on the other.  CO and relight remain.

-------
                                    58
as problems and exploration to resolve the relight deficiency  is continu-




ing, but presently any improvement in relight is made  at  the expense of




CO which is not too sensitive to the burning arrangement  in this case




because the origin of the CO problem is not in the primary zone (where




selective burning helps), but rather in the secondary  which is too short




to permit oxidation of the CO.  CO remains an unresolved  problem if the




final standard is equal to the proposed value.
CF34
     The CF34, a civil version of the military TF34 may be regulated if




used on an airframe finding commercial application.  This engine has




received the least work especially now in light of its likely exclusion




through the general aviation exclusion.  In anticipation of commercial




use, selective azimuthal burning has been investigated on a prototype




engine and a modified combustor simulating sector burning has been rig




tested (sector burning alone left the CO too high).  Because of its high




bypass (6) leading to a low takeoff SFC, its moderate pressure ratioi(20),




and its short combustor leading to short residence times, the baseline,1,




engine already meets the proposed 1984 NOx requirement.









CF700, CJ610                                                  i









     As the CF700 and CJ610 would not be controlled under the proposed




requirement and  as the information in the December, 1976 report is still




essentially correct and current,  these engines will not be considered




here.                                                 .

-------
                                    59
     Table IV-4 presents a summary of  emissions  performance  of  the  GE




engines.  Rig data are identified.   A  projection of  the performance of




the double annular combustor in the CF6-6 and CF6-32 is made, but none




is made for the CFM56 because of the scaling uncertainties.  Expected




availability of the technology is also given based upon the  manufac-




turer's current position and existing  or anticipated problems.

-------
                                                       Table VI-4




                                              General Electric Performance


Engine
CF6-5.0






CF6-6




CF6-32




CF34


CFM56




CF6-80




Concept
Proposed Std.
Production
Sector Burn w/
Nozzle Mod.
Dbl. Annular
Selective
burning (SAB)
Proposed Std.
Product ion
Sector Burn
Dbl. Annular
SAI5
Proposed Std.
Production
Sector Burn
Dbl. Annular
SAB
Proposed Std.
Development
SAB
Proposed Std.
Mod. PFRT
Sector Burn.
SB + adv. idle
SAB
Proposed Std,
Sector Burn
SAB

Technology
Category


2

3
1



2
3
1


2
3
1

2
1

2
2
2
1

2
1


HC
6.7
63.0
1.0

2.4
12.0

6.7
43.3
1.8
2.8
11.0
6.7
48.1
2.0
3.2
12.0
14.4
53.1
12.7
6.7
12.0
1.5
0.9
4.0
6.7
2.0
6,0

EPAP
CO
36.1
119.5
37.1

49.8


36.1
96.5
28.3
61.5

36.1
102.1
29.8
72.6

85.2
205.0
80.0
36.1
79.5
51.7
42.0

36.1




NOx
38.1
60.8
60.8

44.7


33.0
65.7
65.7
35.2

33.0
64.1
64.1
35.6

33.0
24.9
27.0
33.0
42.8
42.8
43.5

45.2




Sk
19
13





20
16
16


21




30
20
20
22.9








Development
Status*

IS
SE

R
ID


IS
SE

ID

IS
SE

ID

ID
ID




IS


ID
Projected
Implcmen- Origin
tation of
Date Data*


ET
ET
1986-7 Rig
1983 ET


BT
ET
1986-7 Proj.
1983 ET

Proj.
Proj.
1986-7 Proj.


ET
Cert. Date

ET
ET
ET
ET

Rig
Cert. Date Rig
                                                                                                                          o
*  TC 53 -
            TV ice
SE « Service Evaluation
ID « In Development

-------
                                  61
                               «




2.    Pratt and Whitney Aircraft




                                            >


     Pratt and Whitney Aircraft .(P&WA)  is  a ^division of  the  United



Technologies Corporation (UTC).  P&WA is  the major producer  of  jet



engines for commercial aviation,  its  most  popular being  the  ubiquitous



JT8D (B727, B737, DC-9) .  It also manufactures  the JT3D  and  the JT9D as



well as several models of military engines.  Another division, of UTC is



Pratt and Whitney Aircraft of Canada, a manufacturer of  small jets and



turboprops for business aircraft.  A  summary of the company's engines is



presented in Table IV- 5.
        of Research and Development Effort
JT9D
     NOx control for annular combustor engines originated around the



NASA Experimental Clean Combustor Program (EGCP).   This portion of the



jointly funded program with NASA utilized the JT9D-7 engine as the  ~ *



testbed, but, as in the GE case, this effort should be considered a  ~:



technology demonstration program, applicable generally to annular



combustors such as are also found in the JT9D-70,  JT10D, and other



engines of similar geometry, specifically those capable of housing the



relatively long vorbix configuration when it is properly sized for its



operational performance requirements.







     The ECCP was divided into three phases:  (I)  preliminary screening



of several concepts, (II) refinement of the best,  and (III) engine

-------
          Table IV-5




Pratt & Whitney Aircraft Engines
Engine
JT9D-70
JT9D-7
JT10D
JT8D-209
JT8D-17
JT8D-9
JT3D
Engine
Class
T2
T2
T2
T2
T2
Tl .
Tl
1981 .
Thrust
228 KN
205 KN
71.2KN '
64 . 5KN
84 . 5KN
1984
BPR PR Combustor
Cert. Number
Application Date Delivered
4.9 24 A . B747 1974
5.2 21.4 A B747 1971
A None 1979 0
Cn-A DC-9-580 0
1.0 17.6 Cn-A B727, B737, DC-9
1.0 15.9 Cn-A B727, B737, DC-9
1.4 13.5 Cn-A B707, DC-8
PROSPECTUS
Prospects of Meeting:
Emissions Performance
HC CO NOx Sk
Operational Mechanical
Performance Performance
Production
Category
III
III
IV
IV
III
II
I
-Time

JT9D-70
JT9D-7
JT10D
JT8D-209
JT8D-17
JT8D-9
JT3D
good

good

— not
good

good

good

no


poor

poor
known —

poor
v« f"
poor

poor

no

X X

X X


X X

XXX

XXX
x ; x . x
XXX

X X

X X
•

X X

X X

X X



X

X


X

X

X


                                                                              NJ

-------
                                  63
                               •



demonstration.  In phase I, three concepts were explored,  (1)'modifi-


cation of a conventional combustor (carbureted lean burning combustor),


(2) a radial/axial fuel staged combustor with preiaix/prevap fuel, prepar-


ation, and (3) an axial staged combustor with conventional injection and


mixing (swirl) called the vorbix (VORtex Burning and mixing),  shown in


Figure 15.  The philosophy behind axial staging is explained in Section


III and Appendix A.  The vorbix was continued into phase II and ex-


tensively optimized so that one version (S27E) was eventually tested in


an engine (phase III).  The concept performed well in the engine demon-


stration and showed the viability of the system (see Table IV-6 below).





     Additional development work is needed to resolve deficiencies in


the concept in order to bring the vorbix to "state-of-the-art" per-


formance, at which time detailed development for specific hardware


application could be undertaken.   The first deficiency was that while


the gaseous emissions were acceptable, the smoke levels were consider-


ably in excess of the standard  (30 vs. 19).  This was totally unexpected


from the results of the rig tests in phase II.  Subsequent investigation


revealed that the probable cause was the main zone fuel injectors which


differed from those used in the rig tests.  Presumably, therefore, this


problem can be eliminated.  The second problem was that several of the


operational and mechanical performance criteria were out of specific-


ation.  In particular,  the temperature profile was slightly beyond


tolerance and because of the  shortage of dilution air  (characteristic of


lean,  staged  combustors),  control would be more difficult.  Also,


coking was observed in  the main stage fuel lines and carbon was de-


posited locally within  the combustor.  Durability was  also called into

-------
             VOlUilX U)W EMISSIONS COMBUSTOK (JT9D-7)
 Pilot zone
fuel injector
Pilot zone
  swirler
Main  zone
 swirlers
                Igniter
                           Main zone
                          fuel  injector
                                                                     I:
                        Figure 15

-------
                                  65
question because of the appearance of  localized  hot  spots  on the  liner.




Finally, the engine performance criteria of  ground starting  and ac-




celeration were deficient.   The latter was marginally  acceptable-(i.e.,




met standards) in most cases,  but quite inferior to  that of  the pro-




duction engine.  This was due  principally to the time  required to fill




the main stage fuel manifolds  above idle power.   Barring a technical




solution, it would seem that the definition  of a flight idle with both




stages fueled would improve the required acceleration  sufficiently.




This would require a squat switch so that ground idle  could be identi-




fied and single stage operation used.   The ground start problem has been




identified as the primary stage fuel injectors.   Yet any change to




correct this problem would likely influence  the altitude relight  which




at this point has not been well investigated anyway.









     In addition to these emissions and performance  problems, the ECCP




configured vorbix suffers from certain mechanical complexities,  the




consequences of which would lead to an expensive and probably difficult—




to-maintain piece of hardware.  Features like the throat and the  90  " '




nozzles and swirlers in the liner and dome make fabrication difficult''




and expensive.  Also, the axial staging leads to the requirement  for




either two axially located rings of nozzle holes in  the outer pressure




casing  (costly) or long cantilevered nozzle  supports in the interior




subjected to  the high temperature (coking and structural problems) as




shown in Figure 16.  The throat section between the  two stages is not




only difficult to fabricate, but is particularly susceptible to failure




because of the:high heat transfer and difficulty in  cooling the region.

-------
                                  66
                               •


This, of course, would lead to high maintenance  expense.





     It was found that, at least in the JT9D-7 application,  both stages


can operate in all flight modes and yet provide  acceptable emissions


levels.  This minimizes the fuel control logic,  enhances  reliability (by


not having the staging cycling on and off repeatedly while on approach),


and lessens the coking tendency in the long secondary stage nozzle


supports (because fuel is always flowing in flight), or alternatively,


improves the engine acceleration (because the secondary fuel manifold,


which might otherwise be drained to prevent coking,  need  not be refilled


prior to fuel flowing into the secondary during  acceleration).  This


situation is in contrast to the GE double annular staging system wherein


CO control dictated pilot stage operation only up through approach power


(30%).  Nonetheless, coking in the fuel passage  was  observed in the main


stage  (which sees a hotter environment) after'the ECCP phase III test-


ing.





     Since the conclusion of  the NASA ECCP, vorbix work has concentrated


on the  development of a new simplified and improved vorbix system rather


than upon the refinement of the one developed during the  NASA work.  A


simplified system would include, if at all possible, a reduction or


elimination of  the throat and reduction in the number of  fuel nozzles


 (the latter may badly affect  the low power emissions as too few nozzles


would  lead to very lean zones between  the nozzles and subsequent quench-


ing  of  the reactions).  Improvements would include lower smoke levels


and  improved operational performance obtained through better air dis-


 tribution and fuel control.

-------
                           67
COMPARISON BETWEEN ADVANCED AND ORIGINAL VORBIX CONCEPTS
              . Advanced E  Program Vorbix
                  Original ECCP Vorbix
                        Figure 16

-------
                                  68
     The post-ECCP vorbix work has been supported by 1R&D  funding  and


                                   3                3
the NASA Efficient Energy Engine (E )  program.  The E  program  is  just



beginning and is directed towards the  demonstration of a lightweight,



lov specific fuel consumption engine in the 140KN thrust size range.



This engine is to be a technology demonstrator  only and is not  intended



by 1IASA to be a prototype.  Hence, the combustor design is not  directly



usable in the JT9D-7; however, the technology is transferable.   The P&WA


                                 3
cosbustor configuration for the E  program will be a throatless vorbix



with 24 aerating nozzles in the primary (vs.  30 for the JT9D ECCP) and



48 pressure-atomized carbureted nozzles in the  main zone with radial



inflow swirlers to provide fuel-air mixing and  flame stabilization in



the main stage.  The fewer nozzles compared with the JT9D-7  should not



necessarily be construed as a simplification as it merely  reflects the



snaller size of the engine (air flow rate:  65  kg/sec vs.  95 kg/sec).



The combustor also features a single plane entry of the primary and



and main stage fuel nozzle supports which are then  cantilevered fore and



aft to their respective locations  (Figure 16).







     The IR&D vorbix study first investigated simplifications  of the



ECC? configuration which  included  a reduced number  of primary  nozzles



and variations in the throat size.  The rig work was done  simulating the



JT9D-7 cycle.  However, despite variations in the primary  stoichiometry,



the emissions performance with these simplifications was  found to be



inadequate.  Additional investigations of advanced  nozzle  concepts



including  carbureted nozzles and aerating nozzles  on reduced length



burners  (for  low NOx) were also carried out.  In  1977,  the carbureted



nozzle work was continued and concepts refined.  A new vorbix configur-

-------
                                  69
                               •



ation (Vorbix II)  was designed and adapted to a can  burner (JT8D).   This



concept employed the tested high power stage (NOx  control) with a  new



primary stage offering potentially improved .low power  emissions..  This



stage utilized the new carbureted nozzles and preheated air for.better



vaporization and mixing.  Testing continues, but no  data are available



by which to judge the potential of the new configuration.






     The status of development work for compliance with the proposed



1981 HC, CO and smoke standards is slightly uncertain  at this point



because the more explicit idle definition in the March 1978 proposal



differs from P&WA's earlier usage on which the bulk  of their effort and



data are based.  This new definition has been found  to have an impact on



the EPAP values of up to 50% which would vastly reduce or even eliminate



their margin for variability in most cases.  The information presented



here is based on P&WA's interpretation of EPA's original idle defini-



tion.  The D-7 and D-70 have separate development  programs and are



discussed separately.






(JT9D-70)






     The D-70 has a bulkhead type burner  (Figure 17).   P&WA began with a



rich primary aerating nozzle configuration and met with  success after



numerpus revisions  to the  liner and nozzle configurations.  Pressure



atomizing nozzles were  also evaluated and found to have  inferior emis-



sions performance,  however.  Development was done with both engine



testing for  emissions (rig data being considered unreliable) and rig



testing for  relight,  coking, and durability and, in addition, a nozzle

-------
                                  70






support program was also conducted to examine nozzle durability, coking,




etc.  Despite a persistent tradeoff between .smoke and NOx (P&WA was




attempting to keep NOx at its January 1976 recommended level),  one




configuration finally yielded acceptable HC,CO,  smoke, and NOx, and




acceptably small penalties in pattern factor and combustor pressure




drop (Figure 18).  Initially altitude relight was deficient,  but minor




alterations remedied that difficulty, improving relight to beyond that




of the production combustor.









     Durability remains a concern because the low emissions air dis-




tribution is considerably different from that dictated by conventional




design.  The aerating nozzles, in particular, suffer early distress.




Durability assessment of alternate construction techniques, alternate




materials, and redesigned nozzles, along with cyclic endurance testing




continue.  Radial temperature profile tailoring began in late  1977 and




should be concluded  in  time for service evaluation in 1979.  Effects on




HC, CO emissions are expected to be minor as the dilution air  is added




too far downstream to impact on the reactions.









 (JT9D-7)









     P&WA experienced more  difficulty with the D-7 combustor which




differs from  the D-70  (see  Figures  17 and 19) by having a short cone  (20




of them) burner  rather  than a bulkhead burner.  On  the basis of the




early  (Phase  I)  ECCP data,  P&WA began with a lean primary short cone




burner with aerating nozzles, which was  compatible with  the existing  D-7




geometry.  After extensive  experimentation,  it"became evident  that  it

-------
               71
 JT9D-70 PRODUCTION COMBUSTOR
           Figure 17
JT9D-70 LOW EMISSIONS COMBUSTOR
          Figure 18

-------
                                  72
                               *


was impossible to satisfy all the emissions requirements (including the


P&WA NOx goal of about 60 gms/KN).   The short cone  burner was deficient


because it restricted the fuel distribution in the  dome, in fact,  wash-


ing the walls with fuel and, secondarily, its inherently lower pressure


drop limited the turbulent mixing in the primary.   Both of these effects


promoted the existence of rich pockets, resulting  in high smoke.  Attempts


to reduce the extent of the rich pockets by leaning the overall mixture


then resulted in lean pockets elsewhere giving rise to excessive HC, CO;


hence a tradeoff existed between HC, CO on one hand and smoke on the


other.





     P&WA finally abandoned the aerated nozzle short cone burner for an


aerated nozzle bulkhead type burner (Figure 20) similar to that used in


the D-70.  This represented a major change, requiring lengthened nozzle


supports, new combustor supports, and a reevaluation of the effective-


ness of the diffuser.  This change resolved the emissions problem when


it was found that smoke:could be controlled independently by the amount


of air admitted through the swirler surrounding the nozzle.  Initial'


configurations gave unacceptable pattern factor, temperature distribu-


tion, relight or pressure drop, but eventually most of these operational


parameters have been  improved to within acceptable limits.  Development
                                                             'r

is expected  to be completed by  the end of  1978 and endurance and per-


formance  testing will continue  through 1979.  Service evaluation should


begin in  1979.





     Table IV- 7 summarizes  the  emissions performance of  the important


low  emissions configurations.

-------
              73
  JT9D-7 PRODUCTION COMBUSTOR
         Figure 19
JT9D-7 LOW EMISSIONS COMBUSTOR
           Figure 20

-------
                                  74
JT3D
     The NOx control effort for can-annular engines  such as  the JT8D has




been limited compared with the annular combustor effort.  The effort




began with the joint P&WA/NASA Pollution Reduction Technology Program, a




program which was designed after the ECCP of the JT9D.   The  program




utilized the JT8D-17 and was initially intended to have three consecu-




tive phases, parralleling those of the ECCP.  However,  the NASA sponsor-




ship was terminated after the first phase, apparently because NASA felt




that continued support of low NOx technology for can-annular combustors




was a benefit only to P&WA and the JT8D (an older engine to  begin with)




and hence not of sufficiently general interest to warrant public funding.




The program, however, was successful as far as it went.  In  addition to




the NASA work, P&WA has carried on some IR&D supported work.









     The NASA work had three elements, each representing a different




degree of complexity.  The elements are outlined in Table IV-6.  The




first involved a continuation of some earlier in-house work on airbl'ast




and carbureted nozzles with airflow redistribution to affect the primary




zone stoichiometry.  In general, such an approach is not  expected to




have much positive influence on NOx.  The  second element involved the




adaptation of the vorbix concept to a can-annular combustor such as in




the JT8D.  The vorbix in this configuration had an airblast primary in




each can and two pressure-atomizing simplex nozzles in  the same axial




plane injecting into  two carburetor tubes  which carried the fuel and




inducted air downstream until past the throat at which  point they

-------
                                  75
                               •


entered the can through swirler orifices forming the secondary or main

burning zone (Figure 21).   The stoichiometry in the carburetor tubes was

rich beyond the flammability limit to avoid flashback into the tubes.
                                           /
This configuration minimized the extent to which the internal (to the

casing) pressurized fuel manifolds were subjected to high temperature

(equal to the compressor discharge temperature 715°K, or higher).  The

third element relied upon staging again, but with prevaporizing and

premixing fuel preparation.  For this system to work safely and prop-

erly, variable geometry features possibly would be required to control

the local stoichiometry at the various power settings; such features

were not explored in this program, however.  Furthermore, without such

features, the total NOx level over the LTO cycle did not improve over

that of the vorbix and the CO was worse due to the very lean stoichi—

ometry.
Element I
Element II
Element III
                                Table IV-6
             NASA/Pratt and Whitney JT8D Program Elements
Minor modifications to the existing JT8D coinbustor
and fuel system; including fuel nozzle modifications
and replacement and airflow redistribution.

Advanced versions of the Vorbix, including carbureted
fuel induction into the main stage.

Premix/prevaporization combustor schemes which employ
the vaporized state of the fuel to control flame
stoichiometry for emissions control.  Variable geo-
metry may be a necessity to achieve acceptable emissions
and stable burning, but this was not explored in the
study.
     The control concepts were tested in a single can (40° sector) rig

-------
                   JT8D VORBIX (NASA - P&WA PRT PROGRAM)
             Secondary Fuel Nozzle    /Crossover Tube
                                                Secondary Swirler
Prevaporizer Tube
                                  Figure 21

-------
                                  77
                               •





at actual engine conditions which tended  to give  higher absolute  emis-




sions levels than an engine test (based on production corabustor data).




VThile a number of deficiencies in operational and mechanical performance




could be and were identified in the program, transient phenomena  were




not even investigated as this requires engine testing for evaluation.




Hence, a major portion of the required performance characteristics is




not yet known, making evaluation of the vorbix's  potential still  more




speculative.









     The emissions performance of the vorbix was  good considering the




preliminary nature of the experiments.  The best  configuration, however,




met only the HC standard while NOx and smoke were 10% higher than the




proposed 1984 standards (higher if a margin for variability were  con-




sidered) and CO, although improved considerably,  was 25% higher.   While




smoke may be improved by continued development, it is a fact that the




corabustor performance in terms of the corabustor inefficiency and  the NOx




emissions index (El) matched that of the JT9D vorbix which has undergone




much more refinement (Figures 22-23).  It is, therefore, difficult to




anticipate  significant CO and NOx improvements with this scheme.   In




fact, the CO level achieved was accomplished by operation at pilot only




during  approach (as opposed to the JT9D scheme which operated both




stages  in the air).  As this may be considered a detriment  (due to the




need tto cycle staging while in flight) , the CO. level may instead in-




crease  rather than decrease with any further development that would




operate only with both stages above ground  idle.   Performance problems




that  have been  identified already are  carbon deposition in  the main




stage carburetor tubes  (due to pyrolysis in the ultra-rich mixtures),

-------
                                     78
                        NOx EMISSIONS PERFORMANCE COMPARISON
                           BETWEEN  JT8D AND JT9D VORBIX
                                    COMBUSTORS
           100
   NOx
    El
/gms N0x\
 kg fuel
            10
                                       JT9D Production
                              JT8D Production
                                                  JT9D Vorbix

                                                  JT8D Vorbix
               300     400       500      600      700

                         Combustor Inlet Temperature (°K)

                                     Figure 22
800
900

-------
                                        79


                   COMBUSTION EFFICIENCY COMPARISON BETWEEN

                        JT8D AND JT9D VORBIX COMBUSTORS
     0.10
O
c
O
•H
O
•H
QJ
C
H

C
O
o
O
                              JT9D-7 Production
     0.01
   JT8D-17

 Production
(Low Smoke)
             JT8D-17
             Vorbix
             JT9D-7 Vorbix
             (Pilot Only)
     0.001
           0
                                            10
12
                                Pressure Ratio


                                   Figure 23

-------
                                  80
overheating of the liner wall,  especially  in  the throat, pattern  factor


deficiency and altitude relight (minimally examined).  The radial exit
                                                                       I

temperature profile (important  for turbine durability) was not  inves-


tigated.  Temperature profile adjustment with any vorbix can be dif-


ficult because the high air demands of the two stages and the cooling


requirement leave little left for dilution near the  exit.  The  other


operational and mechanical performance deficiencies:  appear to have no


special problems that could not be resolved with normal development.




     On the positive side, though, the combustor possesses a lower than


normal pressure drop which can be converted to fuel  savings or  exchanged


for increased mixing and possibly reduced  CO.  Another favorable  feature


of this vorbix combustor in the JT8D is that  no major changes to  the


engine are required (diffuser,  casing, or  transition duct).  Only a


proper fuel control must be designed.




     Further NOx control investigation was conducted by P&WA in 1976


with 1R&D funding after  the conclusion of  the NASA program.  The effort


centered around achieving a simplification of the  vorbix  concept by


reducing or eliminating  the throat and wrap-around carburetor  tubes.


These proprietary configurations  led to compromises  in  the  location of
                                                            ~r
the main stage injection, the  degree of swirl (mixing  and stabilizing),


and' the amount of premixing in the main stage (carburetion).   The emis-


sions performance of  these configurations was degraded,  some pollutants


substantially (HC,  smoke); the operational performance is not known  to


the EPA.  This work is  being continued under a general advanced vorbix


development program whose emphasis is the improvement  in low power

-------
                                  81
                               •






emissions,  largely through advanced nozzle concepts.  Although not




considered  by P&WA a part of  the JT8D  low emissions program  (possibly




because P&WA was convinced EPA would drop the NOx  requirement) ,  the .




experimentation is being performed on  a  JT8D sized burner  can.









     The HC and CO control program originated out  of  the earlier smoke




control program and element I of the NASA program, and  funding via IR&D




has carried the program on.  With the  control concept selected in 1976




(airblast nozzles with proper airflow  redistribution  -  a richer  pri-




mary) , engine testing began in 1977  for  the development of durability




and temperature pattern.  While the  testing has yielded a  configuration




with less margin than hoped for, a number of operational performance




criteria appear to have met or exceeded  that of the production version




now in use:  (1) Better altitude relight,  (2) better  cold  start, and  (3)




no appearance as yet of durability problems.  Two  separate,  but  similar,




burners are normally required for the  JT8D, one for the D-17 and another




for the D-9 model; however, P&WA has concluded  that only minor changes




will be needed for the D-9 to achieve  its proper temperature profile*




(the D-9 has uncooled first stage turbine valves and  hence requires a '




different  temperature profile from the D-17 which has cooled vanes).









     Table IV-7 suininarizes the emissions performance  of several of the




important  low  emissions  configurations.
 JT10D
     This  is a  totally new engine designed to the anticipated needs of




 the next generation of commercial aircraft.  As it was not selected

-------
                                  82
                                *





initially to be used on the new Boeing 757 or 767/777  families,  its




ultimate utilization is in question.  It is intended  to be in the 110-




160 KN thrust range although its final configuration  has not yet-been




established.  If built, it presumably would be certified prior to 1984




and hence its HC, CO emissions levels would be dictated by the proposed




1981 NME standards and not the more severe 1984.newly certified engine




(NCE) standards.  Like all new larger engines, it employs an annular




combustor.









     In anticipation of a low NOx requirement, the JT10D casing and cora-




bustor housing was designed to accept a vorbix type combustor, patterned




after that which would go into the JT9D.  However, pending the develop-




ment of an acceptable vorbix configuration, the 10D would use a con-




ventional, single stage combustor employing only  the  HC, CO controls




used on the JT9D (airblast nozzles and rich primary zone).  The success




of a vorbix type combustor in this application is, of course, uncertain




inasmuch as considerable development work is still required to refine




the vorbix into a state-of-the-art concept.  Further hardware develop-




ment would then be required to apply the concept  to the JT10D configur-




ation.   On the other hand, the P&WA work for the NASA Energy Efficient




Engine Program  (providing a demonstrator engine in the 100 KN class)


                                                             'f

should be very helpful as they are  continuing development of the vorbix




type burner in  that program.









     Despite  P&WA's funding of JT10D emissions since 1973,  little  about




the  combustor geometry, performance, or status is known  to  the EPA at




this  time.

-------
                                  83
                               *



     Table IV-7 presents a summary of the emissions  performance of the


?&WA engines.  Rig data are identified.   A projection of the performance


of the vorbix combustor, as presently configured,  is made for the JT9D-


70 for vhich no testing has been done.   Expected availability of the


technology is also given based upon the  manufacturer's current position


and existing or anticipated problems.

-------
                                                     Table IV-7
                                            Pratt  & Whitney Performance


;ine
JD-70




.'b-7






Concept
Proposed Std.
Production
Aerating Nozzle
w/ Rich PZ.
Vorbix
Proposed Std.
Production
Aerating Nozzle
w/ Rich PZ
Vorbix
:D-209 Proposed Std.




;D-17




:D-9




IS -
R »
Baseline
Aerating Nozzle
w/ Rich PZ
Vorbix (NASA)
Proposed Std.
Production
Aerating Nozzle
w/ Rich PZ
Vorbix (NASA)
Proposed Std.
Production
. Aerating Nozzle
w/ Rich PZ
Vorbix (NASA)
In Service
Research
*
Technology
Category HC
6.7
31.5

2 3.9
3 2.0
6.7
61.0

2 9.5
3 2.1
7.5


2 2.2
3 1.4
8.9
37.3

2 5.6
3 1.6
9.9
. i i
35.1

2 6.7
3 1..6
SE » Service
ET * Engine

EPAP
CO
36.1
87.5

24.4
26.3
36.1
150.0

28.0
30.2
41.2


33.6
67.4
49.9
112.7

46.5
83.1
55.9
124.5

48.5
88.0
Evaluation
Test


NOx
33.0
54.3

48.5
35.2
33.0
61.8

47.4
26.2
33.0 .


54.9
40.7
33.0
60.1

68.4 .
41.0
33.0
52.2

59.1
36.0




Sk
19
8

10

19
8

20
30
25


15

26
24

14
27
26
23

11

ID »
FT =
Projected
Implemen-
Development tat ion
Status* Date



ID, FT 1982 .
R 1986-8

IS

ID, FT 1982
R 1986-8



ID Cert. Date
R ?

IS

ID, FT . 1982
R ?



ID . 1982
R ?
In Development
Flight Test
Origin
of
Data*



ET
Proj .

ET

ET
• ET



Proj .
Proj.

ET

ET
Rig

ET

Proj.
Proj.


oj a Projected
Rig

-------
                                     85
     3.   Rolls Royce









     Rolls Royce is a large British manufacturing  firm,  occasionally




owned by the British government.   Its two major divisions,  Bristol and




Derby, manufacture a variety of civil and military gas  turbine  engines




of their own design as well as of cooperative design.   The  civil  engines




are, in descending order of size, the RB211 family,  Olympus 593,  RB432




(in development),  the Spey family, M45H,  RB401 (in development) and




Viper for the jets, and the Tyne and Dart for the  turboprops.   A  summary




of the company's engines is presented in  Table IV-8.









Summary of Research and Development Effort
RB211
     The RB211 consists of the original -22 model,  the larger -524




model, and the proposed -535 which is smaller than the -22,  but has its




entire high pressure core intact, including the identical combustor.




The -524 was developed with a different combustor designed to alleviate




some of the operational problems experienced by the early -22 combustors,




such as durability and smoke.  That combustor, called the stage I com-




bustor, has since been incorporated virtually unchanged into the -22.




Inasmuch as all models of the RB211 presently utilize virtually the same




combustor, the discussion will generally consider all models together.

-------
                                                 Table IV-8




                                             Rolls Royce Engines
Eng ine
Class
RB211-524 T2
RB211-22B T2
RB211-535 T2
Olympus 593 T5
RB432 T2
Spey 511 T2
Spey 555 T2
M45H Tl
RB401 Tl
Viper Tl
Engine 1981

RB211-524
RB211-22B
RB211-535
Olympus593
RB432
Spey 511
Spey 555
M45H

poor*

poor*

poor*

good

— not
no

no

Thrust
218 KN
187 KN
163 KN
50.7KN
43 . 8KN
32.4KN
1984


poor

poor

fair

no"Std,
known —

no

no
marginal

poor
BPR
4.5
5.0
0
0.64
1.0
3.0
4.2
0

HC

X
?
X
?
X
7

i

X
X

X
X
X
PR
27.2
25.0
19.3
16.1
16.9
16
Emissions
CO

X
7
X
7
X
7



X
X
•'• • .
X
X
X
Combustor
A
A
A
A
A
Cn-A
Cn-A
A
'A
PROSPECTUS
Performance
NOx Sk


X

X



X

X
X X
X
X X

X
Cert.
Application Date
B747.L-1011 1975
L-1011 1973
B757
Concorde
None
GS-II 1963
F-28 1963
VFW-614 1974
None
HS-125
Prospects of Meeting:
Operational
Performance


X

X









(Limited Data)

Number
Delivered
540+
c.80
0
1560+
1560+
38
0
Mechanical
Performance


X

X





X
X
X
X


Production
Category
III
III
IV
I
IV
II-III
II-III
III-IV
IV
I
Time

X
X
X
X
X
X









*    Assuming sector burning is not used.

-------
                                  87
                               •

     Rolls Royce appears to be somewhat behind the U.S.  manufacturers in

the exploration of fuel staging as a means of ^Ox control due largely,

perhaps, to their lack of participation in the NASA Experimental Clean

Combustor Program.  However, since then Rolls Royce has  begun its own

investigation with a goal of a 50% reduction in the NOx  EPAP while main-

taining acceptable idle emissions; their effort has been financed partly

by British government funds.  Due to the short combustor design of the

RB211, similar to that of the General Electric CF6 family, Rolls has

elected to pursue the radial staging approach.



     Two alternative designs were chosen for evaluation, with the

better of the two slated for a proof of concept demonstration (similar

to ECCP phase III) test in March 1979.  The selected design (Figure 24)

is a double annular combustor with the pilot and main stage nozzles

housed within short cones and surrounded by air swirlers to enhance the

fuel-air mixing.  The approach is similar to GE's inasmuch as both have

double annuli of nozzles surrounded by swirlers, forming two stages

separated by a centerbody; both require a dump type diffuser to provide

airflow acceptable to the dome.  However, the differences are also

considerable.



     The GE combustor has the nozzles piercing the flat dome.directly

into the burning volume common to all nozzles in the stage  (see Figure
    f
10) r the Rolls nozzles enter into individual cones wherein mixing,

vaporization and  some combustion of the fuel occurs prior to passage

into the annular  burning zone.  The Rolls conbustor provides for cooling

-------
LOW NOx POUBLE ANNULAR COMBUSTOR (ROLLS ROYCE)
                      PILOT BURNING
                        ZONE
                       MAIN BURNING
                         ZONE
                                                                            oo
                                                                            oo
                  Figure 24

-------
                                  89
of the centerbody which is not found  on  the  original GE version of  the




double annular combustor,  although a  later version as planned for in the




E  program with NASA has centerbody cooling.   The Rolls arrangement




requires, unfortunately, a new combustor casing  and a new diffuser  (the




original RB211 diffuser being a smooth type),  although not evidently a




diffuser casing.  The GE combustor was designed  to fit into  the existing




CF6-50 envelope although application in  the  CF6-6 vould require a new




diffuser and casing (the -6,  like the RB211, has a smooth type diffuser).




Also, it is of significance that the Rolls double annular combustor has




72 nozzles fed through 18 bosses.  It thus has four times the nozzles of




the production engine (18), but manages  to minimize the impact on the




casing by utilizing the existing boss arrangement.  In contrast, the GE




double annular combustor only doubles the number of nozzles  from 30 to




60, using the same bosses also.









     Rig demonstration and development of the  concept has been ongoing




since mid-1977 and is expected to continue  through 1979 in an effort to




resolve a number of difficulties which include ignition and  temperature




profile shortcomings and, especially, inadequate emissions reductions.




The actual performance demonstrated to date  in the rig is not known to




the EPA nor are other important operational  points such as the need for




in-flight staging (as in  the GE combustor).  New ideas are still being




investigated, but the program is continuing  with an engine demonstration




(equivalent to  the NASA ECCP phase III testing)  scheduled  early  in 1979.




Design and development of production quality hardware will begin  in 1979




and will involve separate, but similar,  combustors  for  the  three  vari-

-------
                               .90




ants of the RB211.  Full production is possible in 1986,  if no major




development difficulties arise.









     In addition to fuel staging, Rolls Royce has  investigated the




potential of NOx control via quick quenching used  in conjunction with an




extended rich primary zone that is swirl driven.   This  approach was very




similar to that explored by GE in the CFM56 engine.  Their program goal




was a 25% reduction in NOx.  This combustor has been tested on a -524




engine and while the excessive CO and smoke demonstrated  that this was




not a solution in its present developmental state, the  potential does




exist.  The actual EPAP figures for the -524 test  are not known, but a




Rolls Royce extrapolation of the data to the -535  operating conditions




(lower pressure ratio, in particular) predicts that the -535 would meet




the 1984 NOx requirement.  This is called the stage III combustor and is




discussed again in the HC, CO section.









     Acceptable HC, CO emissions in the RB211 have followed a long path




since the original 1967 design.  The original combustor,  although




possessing a slightly lean primary zone and airblast nozzles  (simplex,




however) suffered a high degree of non-uniformity  (inadequate mixing)




which resulted in excessive smoke emanating from rich pockets.  Com-




pounding the problem was the fact that the combustor had only 18 nozzles




 (each 20 ) despite the engine being equal in size  to the CF6  (30 nozzles)




and the JT9D  (20).  Correction of this problem (smoke being considered a




nuisance even before the 1973  regulations) led to  a redistribution of,




as well as an overall leaner,  stoichiometry in the primary, both conditions

-------
                                     91
of which would lead to less smoke production.   However, as this led to

very lean conditions at idle, the combustion efficiency there suffered,

giving the -22 the worst idle emissions among the new high pressure
                                            ^
ratio engines.  This combustor was referred to as the stage I combustor

(Figure 25) and as it entered service in 1975, it permitted the RB211 to

comply with the 1976 large engine smoke standard.




     A parallel development, the stage II combustor (Figure 26), was

initiated at the same time (1973) in an effort to improve the HC, CO

emissions and a number of operational and mechanical deficiencies of the

stage I burner.  This combustor operates with a richer primary (by

airflow redistribution and new airblast simplex injectors) , and yet

provides sufficient uniformity to keep the smoke within limits.  The

stage II is now entering production in the -22B and -524.




     The operational and mechanical performance of the stage II burner

is indeed superior to that of the stage I burner; hoxv'ever, it does not

provide sufficient emissions control.  The control improves in the higher

pressure applications.  The performance of the -524 (PR = 27), for instance,

is roughly equal to that the best non-sector burning CF6-50 technology.

On the other end of the spectrum, the smaller -535 (PR = 19) with the

stage II burner is little better than the baseline JT9D-7.  Hence, Rolls

Royce has explored other avenues to supplement or replace the stage II
     *
combustor.  Operational control by compressor bleed and sector burning,

in particular, have been investigated to supplement the stage II combustor.

Sector burning by firing 12  of the 18 nozzles (a 240   sector) at idle

permits the -524 version to  approach HC, CO standards.  However, the

data available to the EPA show that the -22B, operating at a lower idle

-------
STAGE I COMBUSTOR
   Figure 25

-------
STACK  11. COMM.U;TUK
                                                                       U)
     Figure 26

-------
                                    94
pressure and with a loxver rated output,  is still well  above the stan-




dards despite the sector burning.   The -535 fares  even worse.   Additional




improvement is not expected by firing fewer than  12  nozzles during




dector burning (GE fires only a 180  sector),  as  the stoichiometry is




optimized at 12 firing.









     Rolls Royce is committed to the stage II combustor  in all applications




at the present, largely because of their contractual guarantees for long




combustor life, but also because of the economy involved in having a




single combustor for all engines.   This is true even for the -535 model,




which being new, might normally be expected to have  a  shorter initial




combustor life.                                                    .









     As insurance against the failure of the emissions performance of




the  stage II burner and out of expectation of failure  for the -535,




which operates at yet  a lower idle pressure and with less rated output




than the -22B, Rolls began preliminary work in 1977  on the stage III




burner, which employs  an extended rich primary zone, stabilized by   i ,




substantial swirl from around the nozzles, and followed  by a quench to




stop the NOx reactions (Figures 27 and 28).  This burner is presently in




the  research stage and with a commitment to proceed, it  would be available




in 1985 or  1986  (service evaluation included therein).  The only emissions




performance data  for the stage III combustor which is  available to EPA




is that froni an early  version of  the  combustor which did not have the




strong  swirl aerodynamics in  the  primary driven by the swirl cups around




the  nozzles  (see  Figure  28).  That data shows the emissions performance




to be still insufficient.

-------
                                     95
     Rolls Royce  is  predicting  that a fully developed combustor with

 acceptable operational and mechanical performance could have an HC EPAP

 of  less  than  20 in an RB211-535 application.  This is a considerable
                                            f                    •  •
 improvement beyond the stage II (EPAP =  35), but it is still little

 better than the baseline JT9D-70  (It must be remembered, however, that

 the JT9D-70 combustor was designed initially with emissions in mind and

 is, therefore, much  cleaner than  other presently produced engines).

 Significant CO improvements are unlikely because the quick quench design

 would  promote the freezing of the CO ->• CO  oxidation outside the primary.

 This represents a prime example of CO-NOx tradeoff inasmuch as this

 quick  quench  feature reduces the  NOx from an EPAP of 51 for the stage II

 combustor  to  possible 30  for the  stage III  (marginally below the  1984

 standard).  Nonetheless,  the addition of the swirl should have some

 beneficial effect on the CO level, in particular, although a prediction

 cannot be made.   Again, it is possible that the addition of sector

 burning to the stage III combustor might provide a sufficiently favorable

 environment at idle  to promote  faster CO oxidation and offer additional

 HC  control.   However, this cannot be relied upon without demonstration

 because with  the  primary  already  redesigned to provide a hotter,  richer

 flane  at idle, further richening  may be  excessive and in fact increase

 the CO emissions  (see Figure 33).

                                                             *t
                                                             £

     Table IV-10 presents  a summary of  the emissions performance of  the
     ^
 RB211  family.



 Olympus 593



     This  is  the  only T5  class  engine  in use.  It is an outgrowth of  an

older family  of Olympus engines, but was  considered best suited  to the

-------
                     96
COMPARISON BETWEEN LOW EMISSIONS COMBUSTORS
                      Stage II
                       Stage III






                 Figure 27

-------
STACK  I'll:  COHIHJSTOK
     Figure  28

-------
                                   98
cask because it was sized right and possessed the proper thermody-iaraic


cycle for supersonic flight (moderate pressure ratio  and no bypass).


This engine is a collaborative project, with SNECMA responsible for the


development of the afterburner, a feature not found on engines intended


for subsonic use.  Because of the vintage of parent engine, the 593


began with a can-annular type of combustor (like the  P&WA JT8D and RR


Spey) with pressure atomizing nozzles.  Smoke problems early on precipi-


tated a conversion to an airspray type of nozzle (an airblast nozzle


similar to some of GE's with a low pressure orifice surrounded by a


swirl ring).  This improved mixing and leaned out the primary zone.


However, this too proved inadequate, largely because the requirements of


coast-down from supersonic flight forced the use of a very rich primary


zone.  This led to a total redesign of the combustor resulting in the


enployment of a modern annular combustor (like, e.g., that in the JT9D


or RB211) and vaporizer injectors.





     Vaporizer injectors are not used by any U.S. manufacturers, but are


found in several Rolls Royce combustors of various vintages (see Ap-


pendix A, /-'I).  It is basically a premix/prevaporizing concept wherein


low pressure fuel is injected  into a tube which also contains a portion


of the compressor air entering the burner dome.  The heat of the com-
                                                            v

bustion within the primary zone into which the vaporizer tube is in-


serted vaporizes the fuel stream before it flows out of the tube into


the primary.  The usual configuration has a reverse flow at the exit,

-------
                               • 99


making the vaporizer resemble either a "l" or a walking cane ("J") as


the case may be.  Both the cooling needs of the vaporizer (done by the


fuel) and the prevention of flashbacks require very rich stoichiorr.etry
                                           r

in the tube.





     Because of the relative leniency of the T5 standards compared with


the T2 standards, Rolls Royce is able to comply with the 1980 require-


ment (HC, CO only) with only the application of their "blown ring".


advanced cooling technology.  This technology, which is also employed in


the M45H (discussed below) controls the amount and direction of cooling


air into the dome so that premature quenching of the reactions near the


wall is avoided.  While this advanced cooling scheme does result in


marked HC, CO reductions (to the levels required by the T5 standards),


nevertheless, the combustor still has a greater combustion inefficiency


at idle than would be expected of a new high pressure fan engine  (e.g.,


the JT9D) run at those operating conditions and using the best HC, CO


control (Figure 29), despite the fact that  the high pressure engines


need and are designed for high liner cooling flows capable of signif-,


icantly quenching the reaction.                                      -.-.





     Additional combustion inefficiency  (HC, CO) is found in the after-


burner employed at takeoff.  This  is to be  expected in light of the low


pressure (though high temperature) and short residence time.  Methods to
    ^

improve the combustion efficiency  have apparently been identified by


SNECMA, the responsible partner, which would raise the efficiency from


95% to 99%  (downstream from  the exhaust at  the completion of reaction).

-------
                               .100


Such methods would presumably include better and more rapid mixing of


the fuel-air mixture, probably at the expense of a slight increase in


the pressure drop across the afterburner (and therefore poorer fuel


economy).





     The standards for T5 newly manufactured engines do not include any


significant requirement for NOx control, the standard in fact permitting


a minor increase in NOx in exchange for CO control.  Consequently, no


technology for NOx control has been investigated.                       .
RB432
     The RB432 is a new engine now under development which is sized to


compete directly with the existing JT8D.  The engine was begun as a


successor to the Spey although its size has now grown somewhat beyond


that.  It is essentially a straightforward scale-up of the 25KN RB401


engine which is also under development for the business jet market.


Very little is known about the engine at this time in view of its early

                                                                    •-.•** !
stage of development.  The smaller RB401 has been designed by Rolls to


satisfy the presently promulated Tl class emissions standards and con-


sequently, it may be expected that the larger RB432 would perform as

                                                             i~
well.  The combustor is annular with vaporizer nozzles.
 Spey
     The  Spey  family  consists of a large number of members which orig-


 inated  in 1963 (date  of  first certification).  Being of older vintage,

-------
                                    101

                   COMPARISON OF EMISSIONS PERFORMANCE,
                           JT9D AND OLYMPUS 593
0.1
0.01
 .001
                                                       Production

                                                       Low Emissions
                                                                      14

-------
                               .102





the Spey uses a can-annular burner (Figure 30),  with  duplex high pres-




sure fuel nozzles.  Beyond that, it suffers three additional disad-




vantages, the first being a low bypass ratio (0.6-1.0)  giving it a high




sea level SFC compared with modern engines; the  second  being a larger




nunber (10) of highly loaded short cans, and the third  being a burner




fabrication technique which uses "wiggle strip"  cooling (Figure 31).




This approach to supplying cooling air to the burner is simple, but




excessive, yielding a can with exceptional durability (16,000 hrs.).




The excessive cooling air, coupled with the small size  of the cans




(implying short residence time and larger surface to volume ratio which




enhances the importance of quenching of the reactions by the cooling




air) together create an environment conducive to incomplete combustion,




especially at idle.  Hence, the HC, CO emissions are very high (idle




cotabustion efficiency is only 90%) and extraordinary effort must be made




to reduce them.  Smoke also is a problem due to poor mixing in the




primary  zone, a result in part of the small pressure drop across the




combustor head which is, in turn, partially a result of the large cool-




ing air  flow  (low  resistance).









     Low emissions work first began in  1969 when Rolls was first con-




tracted  by the USAF to produce  a  low smoke  combustor for the TF41  (a




military Spey).  Both a piloted airblast nozzle and a revised  combustor




head configuration (the conical head) were  investigated  (Figure 32).




These  approaches  reduced smoke  (to SAE  No.  14)  through improved local




stoichioinetry, but without  any  concurrent  HC, CO reduction.  Addition-




ally,  the  conical  head scheme,  which was  the better, suffered  persistent

-------
Spey Production Burner
                                                                           o
                                                                           CO
       Figure 30

-------
              104
COMBUSTOR LINER COOLING METHODS
     Wiggle Strip Cooling
     Splash Plate Cooling
           Figure 31

-------
                               105
                               •


and severe carbon deposition and durability problems.   A low HC, CO



emissions (as well as smoke) investigation was begun in 1972.  This



program, was quite extensive, involving half a dozen different approaches



and nearly 400 rig and engine tests through 1976, at which time Rolls



concluded that while substantial reductions to the HC and CO could be



made, compliance with the existing HC and CO standards (and for that



matter, with the proposed regulations) was impossible.  The basic con-



cepts that were investigated are listed in Table IV-9.







                              TABLE IV-9


                   Low Emissions Investigation - Spey



1.   Improved atomization



2.   Airblast nozzles



3.   Sector burning



A.   Advanced cooling



5.   Vaporizer nozzles



6.   Reflex airspary burner  (RAB)







     There was a considerable variation in the degree of success and'the



difficulties encountered among these six concepts.  Improved atomization



was possible by rescheduling the duplex nozzle fuel flow to run on the



primary only at idle.  The primary, being sized for ignition, gave good



atomization at low power and, if used alone, afforded some reductions.



Apparently, though, this was not the principal source of the emissions



as the amount of control was quite modest.  Piloted airblast nozzles



reduced smoke by leaning the primary zone some and improving mixing at

-------
CONICAL HEAD BURNER (LOW SMOKE)
           Figure 32

-------
                               107

                               •



high power, but had even less effect on the emissions at low power, both



because poor atomization was not the principal source and because the



airblast feature was least effective at the low pressure drops expe-
                                           f


rienced at idle.








     Sector burning provided considerable reduction, especially of HC,



by richening the primary (the Spey runs slightly lean at full power, and



leaner yet at idle in normal operation) and improving atomization.  This



large improvement would not necessarily be witnessed with combustor



configurations other than the production (its success is very dependent



upon the sensitivity of the combustion efficiency to the fuel/air ratio



in the primary as is seen in Figure 33), but inasmuch as sector burning



alone cannot achieve.compliance, then compounding of this with other



schemes for emissions reduction would be mandatory.  However, it is



understood that this sector burning was achieved by the elimination of



only 3 of the 10 cans (leaving a 252  sector on).  GE fires only a 180



sector to achieve its reductions and while this adds to the potential



operational  and mechanical problems, it is likely to be more effective.



An engine test of sector burning with 3 cans out resulted in the burnout



of some nozzle guide vanes so the mechanical problems are indeed a



reality.  Also, sector burning in a can-annular system results in



peculiar crossover flow patterns resulting from a difference in pressure



drop between the lit and unlit cans.  This possibly would affect the



liner durability.  On the other hand, the primary zone stoichiometry  is



not the only contribution to the emissions problem as was discovered



during the investigation of advanced cooling.

-------
                             Impact  of  Combustor Design on
                            Effectivenss  of  Sector Burning
o

o>
•H
O
•H
W

c
o
•H
4J
W
3
,0

O
     Improvement  in
     Low  Emissions
     Burner by  Sector
     Burning
          Low Emissions Burner
                                                                         Sector burning
                                                                         operating line
      Improvement  in
      Production Burner
      by  Sector Burning
                                           Production Burner
                                                                                                         o
                                                                                                         CO
vFull annular
 operating line
                               Fuel/Air Ratio (Primary)


                                       Figure 33

-------
                               109


     Advanced cooling schemes are based upon recognition that the

primary source of HC, CO emissions in the Spey is the reaction quenching

that occurs adjacent to the lean primary at'idle.  Sector burning, in

contrast, richens the primary to reduce the quenching effect, but

advanced cooling attacks the problem directly by designing the combustor

to survive without the excessive film cooling that is provided (without

choice) by the "wiggle strip" construction.  The basis of the advanced

cooling is the use of a new composite sheet material (unknown to EPA)

which is more durable in the thermal environment than what is now used

in production.  This requires less cooling air to provide the same

excellent life and, therefore, permits the redesign of the cooling air

patterns accordingly.  Fabrication problems have been solved and the

operational performance has not degraded.  The major mechanical problem

seems to be the interface between with the composite and the conven-

tional materials in the latter half of the liner.  Experiments have

shown that about half of the quenching was at the head and the other

half in the front portion of the liner, so all of this must be made of
                                                                    ^ «.
the new material.  Idle combustion efficiency increased from 90% to

96.9% using production nozzles which is, unfortunately, still insuf-

ficient.  Continued development would necessarily consider the effect of

compounding schemes, in particular, the mating of the advanced cooling
                                                             .'
burner with such as cross stream aerated injectors, piloted airblast

noz2les, sector burning, blown rings (see Olympus or MASH), and enhanced

mixing domes  ("potted head").



     Vaporizer nozzles were investigated early, being a standard feature

-------
                              110
                              •



on other Rolls Royce engines (e.g.,  M45H).   Although  emissions  were re-



duced some (smoke especially) and most operational  criteria were  satis-
                                           j


factory, relight was much degraded,  evidently  due to  the airfloxy  dis-



turbance resulting from the blockage caused by the  vaporizers  themselves



(5 per can).   This in turn led to the development of  the reflex airspray



burner (RAB).                                 .







     The RAB as developed is not merely a fuel injector concept,  al-



though that is an important facet of it.  The  RAB includes a radical



change in the primary zone aerodynamics, specifically a dual reversal



flow which acts as an aerodynamic staging system (see Figure 34) .  The



first reversal is sized for idle and the second for takeoff.  At  take-



off, the first zone burns excessively rich (without fuel staging, it



still accepts all the fuel) and acts as pilot  zone  for the second re-



versal.  A simplex injector is employed and located within a carburetor



tube which acts as a vaporizer.  Evaluation of numerous variants  has led



to a best version attaining a 98.4% combustion efficiency at idle with



an improved pattern factor.  Additional work resolved earlier head



cooling problems, but the deteriorated ignition and relight has remained



intractable.  In theory, the concept also has  the potential for NOx     :



reduction by  controlling the residence time in the second reversal zone.



Although two  attempts at control gave 30% and 50% reductions ^ they could



    be  achieved without deterioration of the still high idle emissions.
     The RAB and  the  advanced  cooling approaches gave the best emissions



 (Table IV-9), but because  of the  constraint upon resources, Rolls was

-------
KF.FLKX AIKSPRAY BURNER
       Figure 34

-------
                               112




forced to select only one for continued development.   In 1977,  Rolls




chose to abandon the RAB for although it gave the best emissions,  the




relight and ignition problems appeared insurmountable while,  on .the




other hand, advanced cooling seemed to have the potential to  at least




match the RAB emissions performance with better operational performance.



                                                                      /




     Table IV-10 summarizes the.Spey performance to date.
M45H
     The M45H was originally a collaborative project with SNECMA and was




developed for application in the short haul airlines, the VFW-614.   The




airliner, however, had few buyers and production ceased in 1978 after




only 16 were built, thus leaving the M45H without purpose.  Since 1976




Rolls Royce has taken over full responsibility for the engine which is




now its own.  The engine is quiet and fuel efficient which is likely to




be favored in future aircraft for which its size is appropriate.  A




large refanned version using the same core, called the M45SD (RB410)* has




been demonstrated and should expand its potential for future applica-




tion.  In fact, the -SD at 64KW is sized slightly larger"than Spey and




so is a potential replacement.  The -SD remains a collaborative venture




with SNECMA and Dowty Rotol.                 .









     The engine utilizes an annular combustor with vaporizer nozzles




 (walking cane configuration).  Its production version is quite high in




HC and CO due to reaction quenching at the wall by entrainment of the

-------
                               113






fuel into the film cooling air.  However,  employment  of  the "blown ring




advanced cooling technique, used also in the Olympus  593,  brings the HC




and CO emissions to within the proposed standards.  The  NOx emissions




are already below the proposed.level because of the moderate pressure




ratio and low sea level SFC which occurs as a result  of  the moderately




high bypass ratio.  It remains to be seen, however, if there is suf-




ficient margin (for CO and NOx especially) for variability, but if not,




slight modifications to the liner to provide a better airflow distri-




bution may prove sufficient.  Other low emissions concepts which had




been investigated earlier on the M45H were redesign of the vaporizers,




alternative schemes to fuel the vaporizers (specifics unknown), and




leaner primary zone stoichiometry, but none of these  were successful in




lowering the emissions to the requisite level.









     Further low emissions development work has ceased pending the




identification of a new application of this engine.









     Table IV-10 presents a summary of the emissions performances of 'the




various Rolls Royce engines.  While most data was obtained by engine'*"




testing, some was from either  rig testing or was derived from extra-




polation from other conditions  (e.g., the RB211-535 data).  In certain




cases, the data, while showing excellent emissions control, may also




reflect unflightworthy hardware or operationally defective systems.




Therefore, care should be  exercised in the evaluation of the potential




success an engine may have in  achieving a given emissions level.

-------
                                                       Table IV-10
                                                Rolls  Royce Performance
              Concept
Technology
 Category
'•211-22B  Proposed Std.
          Production
          Phase II                 2
          Phase II w/ sector burn  2
          Double Annular           3

•>211-524  Proposed Std.
          Production
          Phase II                 2
          Phase II w/ sector burn  2
          Double Annular           3

v211-535  Proposed Std.
          Phase II                 2
          Phase II (7% idle)       2
          Phase II w/ sector burn  2
          Rich  PZ w/ Quick Quench  2
Iytr.pus593 Proposed Std.
          Production
          Blown ring

pey MK511 Proposed Std.
          Production
          RAB
          Advance cooling

pey MK555 Proposed Std.
          Production
          RAB
          Advance cooling
     2
     2
     2
     2
45H-01'    Proposed Std.
          Production
          2 Bloxm. rings (7% idle)  >2
EPAP
HC
6.7
135
8.3
4.2
6.7
110
6.0
. 3.1
6.7
19.1
32.4
8.9
2.5
30.7
129
<30.7
12.2
278
23.0
75.5
13.6
441
36.1
75.6
16.2
162
30.1
CO
36.1
172
49.6
28.8
36.1
145
39.0
22.4
36.1
90.0
96.6
54.7
67.5
237.0
530
<237
70.9
436
162
229
79.8
420
186
232
97.1
526
169.9
NOx
33.0
51.9
61.7
64.0
34.6
61.4
68.0
7.0.2
33.0
49.0

51.3
30.3
70.8
70.1
<70.8
33.0
68.1
68.2
58.0
33.0
49.5
55.2
54.2
33.0
31.2
37.0
Sk
                                                                             20
                                                                             15
                                                                             18
                                                                             19
                                                                             18
                                                                             18
                                                                             21
                                              25
                                              26
                                              28
                                              66
                                               29
  IS = In Service
  R  a Research
       SE = Service Evaluation
       ET. = Engine Test
                                               31
                                               46
                                               12
                                                                             ID
                                                                             FT
                                                                                    Development
                                                                                       Status*
                                                           IS
                                                          ID, FT
                                                           ID
                                                            R
                                                           IS
                                                          ID, FT
                                                           ID
                                                            R
                                                                                         ID
                                                                                         ID
                                                                                          R
                                                                                          R
            IS
           ID, FT
            IS
            ID
            ID
            IS
            ID
            ID
            IS
            ID
      In Development
Projected
Implemen-
 tation
  Date
                                                                                                      1982
                                                                                                      1986+
                                                                                                      1982
                                                                                                      1986+
                                                                        1983
                                                                        1983
                                                                        1986
                                                                        1986+
                                                                       1980
                                                                                                    Cancelled
                                                                                                      1982
                                                                                                   Cancelled
                                                                                                     1982
                                                                                                  In abeyance
                                                                                                  pending new
                                                                                                    orders
                                      ET
                                      Rig
                                      Rig
                                      ET
                                      Rig
                                      Rig
                                      Rig»  C78)
                                      Rig C'79)
                                      Proj
                                      Rig
                                                                                                                   ET
                                                                                                                   Proj
                ET
                ET
                Rig
                                                                                     ET
                ET
                Rig

-------
                                .115






     4.    Avco Lycoming









          Avco Lycoming (generally referred ,to as simply "Lycoming")  is




a U.S. manufacturer of both piston engines (Williamsport,  PA)  and gas




turbine engines (Stratford, CT) for aircraft.   It is a subsidiary of  the




larger Avco Corporation.   The gas turbine division produces principally




shaft power turbines for fixed wing aircraft and helicopters,  largely




for military applications.  Of interest here,  however, is the  new ALF




502 turbofan engine of the Tl class.  Because of its size (29-34 KN) , it




would be subject to the proposed standards if used commercially.  A




description of the ALF502 is given in Table IV- 11.









Summary of Research and Development Effort









     It was recognized early that the prototype 502 would not  comply




with the standards promulgated in 1973.









     The basic engine core is  that of the T55 turboshaft engine (2800




KW), a design which dates back to about 1960.  That core was first tried




in jet applications in the F-102, a military predecessor to the ALF502




series.  Although  the cores are essentially the same, minor combustor




modifications are  necessary in the new applications in order to provide




acceptable performance in  the  new environment (e.g.,  increased cooling




in higher pressure applications).  The cotnbustor is a reverse flow




annular type and is the only such one affected by the proposed stan-




dards.

-------
  Table IV-11




Lycoming Engines
Engine
ALF502D
ALF502H
ALF502L
Engine
ALF502D
ALF502K
ALF502L
Class Thrust
Tl 28.9KN
Tl 29.8KN
Tl 33.4KN
1981 1984

fair
fair
7
7
fair
marginal
BPR PR
5.8 11.1
11.4
13.3
Emissions
HC CO

X
X


X
X
Cert. Number Product io
Combustor Application Date Delivered Ciitep.ory
RFA None 1976 0
RFA HS146 — 0
RFA Challenger 1979 0
PROSPECTUS
Prospects of Meeting:
Performance Operational Mechanical
NOx Sk Performance Performance

X
X


X
X X
IV
IV
IV
Time



•„.




-------
                                 117
     The baseline engine, employing the T55 standard dual orifice




nozzles, required more than a 50% reduction in KG and CO emissions to




-eet the 1973 mandated levels.  This was due largely to the fairly low




conbustor inlet temperature experienced at idle which made vaporization




difficult and the reaction speed slow.   Countering this to some degree




was the excellent fuel dispersion which arose from the large number of




nozzles (28, each covering only a 13° sector).









     Methods to reduce HC, CO emissions logically centered around means




to enhance the fuel vaporization.  Vaporizing injectors similar to those




used by Rolls Royce on some of its engines were investigated; however,




because of the low air temperature entering the combustor, the vapor-




izers could not function adequately.  This was unfortunate in that such




injectors have the potential  to reduce high power NOx production suf-




ficiently (15% or more) on the 502 to achieve compliance with that




standard also.









     Airblast injectors were  also tried with greater success.  These




injectors, supported by coinbustor airflow  redistribution, provided the :




best KG, CO control although  the best configuration still failed to meet




the 1973 HC and CO requirements and, in addition, suffered from degraded




operational and mechanical performance.  Subsequent development to




improve upon  these deficiencies increased  the HC, CO emissions somewhat




(certification configuration).  Variations in the primary  zone stoi—




chioiaetry,  cooling air flow mixing patterns,  and residence times were




explored and  tradeoffs between reductions  in HC and CO on one hand and




radial  temperature profile, pattern  factor, and the lean stability limit

-------
                                118
                                *


on the other were found to exist which could not be eliminated.




     Lycoming has never emphasized research on NOx control, preferring


instead to rely upon the output of the NASA Pollution Reduction Tech-


nology Program for Small Gas Turbines (PRTP-SGT), the contract for which


had been awarded to AiResearch rather than Lycoraing.  This program 'will


be completed in 1979.  Nonetheless, Lycoming claims to have examined NOx


control techniques such as preinixing, fuel staging, and staged air


introduction.  Nothing is known about the extent of the work and pre-


sumably it has not been carried beyond preliminary rig testing.  Ac-


tivity in this area was continuing in 1977, but. no further information


has been provided.




     With the loss in 1976 of the contract for the U.S. Coast Guard


medium range surveillance aircraft which v/ould have used the ALF502H


model, the first use of the  502 now appears to be the Canadian Chal-


lenger (formerly Learstar 600), a new business jet which employs two


502L engines.  The L version, using nearly the same combustor as the D,'


(except for minor durability changes) also fails  the 1973  requirements!


In fact, at the originally specified idle of 1800 KN, it suffered  a


greater combustion, inefficiency  (HC and CO) than  the H model, apparently


because of its even  lower pressure and temperature.  To achieve com-


pliance, Lycoming resorted to an advanced idle point which is an op-
   •

erational  control  technique. Unfortunately, the  approach  borders  on  the


desperate  in  this case,  for  an  idle power of 10.7%  is required  (3580  KN)


which has  precipitated  a need for  thrust spoilers at idle, thus adding


weight as  well as noise.  In fact, while the 10.7%  is ample-for an


adequate margin  for  variability under the  1973  standards, the proposed

-------
                                  119
                                •


standards, although relaxed in principle, do not give-"credit" for a

high idle in the denominator of the control parameter and hence nearly

all of the margin is eliminated.  How Lycoming plans to deal with this

is uncertain at this time.




     Certification of the Challenger is planned with the high idle and

thrust spoilers and is expected next year.  Under 1973 standards,

Lycoming was in an excellent position to comply in a timely fashion;

however, with the proposed standards and the eroded margin, its status

is less certain, although the two year delay should be sufficient for

adjustments to be made.  The biggest advantage for Lycoming and the

Challenger is the general aviation exclusion which eliminates the ALF502

from control unless, perhaps. Federal Express decides upon the Chal-

lenger in addition to its freight fleet.  The ALF502 is also scheduled

for use on the new four engined HS146 short haul airliner by British

Aerospace Corporation (formerly Hawker Siddeley).  However, this air-

craft appears to be aimed principally at the European market and thus

would not be under the umbrella of the standards.  Should U.S. commuter,

airlines  decide to buy it, hox^ever, Lycoming would again be confronted.

with the  issue whether to proceed with advanced idle in this application

for emissions control.

                                                              -•-.


     Table IV-12 summarizes  the emissions performance of the various  502
   •                             _                       .
configurations.

-------
                                                        Table  IV-12
                                                   Lycoming  Performance












Technology
Engine
ALF502D

Concept
Proposed Std.
Prototype
Category


Airflow distribution


2
HC
17.
31.
14.

0
0
8


EPAP
CO
103
183
112



NOx
33.0
38.3
28.8



Sk
32

25


Development
Status*


IS
Projected
Implemen-
tation
Date


Cert.

Orgin
of
Data*


ET
plus airblast nozzles
ALF502L


Proposed Std.
Baseline (same as
Cert, configurat
Advanced idle

502D
ion)



1
15.
28.
9.
9
6
1
95.5
136
92.2
33.0
32.3
35.4
31



FT
FT

1982
1982

DT
ET f
*  IS = In Service
   R  = Research
 Proj = Projected
 SE = Service Evaluation
 ET = Engine Test
Rig =
ID = In Development
FT = Flight Test

-------
                                   121
                                 •

                               References
 1.  Aircraft  Emissions:   Impact on Air Quality and Feasibility of
    Control,  EPA (no  date).                  ,

 2.  Assessment  of Aircraft Emission Control Technology, NREC, EPA
    Contractor  Report No. 1168-1, E. K. Bastress, et al., September
    1971.

 3.  Control of  Air Pollution  from Aircraft and Aircraft Engines, 40
    CFRPt87, FR 3£,  N.  136,  July 17, 1973, p. 19088.

 4.  Aircraft  Technology  Assessment - Interim Report on the Status of
    the Gas Turbine Program,  EPA, R. Hunt, et al., December, 1975.

 5.  Aircraft  Technology  Assessment - Status of the Gas Turbine Program,
    EPA, R. Hunt and  E.  Danielson, December, 1976.

 6.  Control of  Air Pollution  from Aircraft and Aircraft Engines, NPRM,
    FR 43^, N. 58, March  24, 1978, p. 12615.

 7.  Review of Past Studies Addressing the Potential Impact of CO, HC,
    and NOx Emissions from Commercial Aircraft on Air Quality, EPA AC
    78-03, P. Lorang, March 1978.

 8.  An Assessment of  the Potential Air Quality Impact of General
    Aviation  Aircraft Emissions, EPA, B. C. Jordan, June, 1977.

 9.  Potential Impact  of  NOx Emissions from Commercial Aircraft on N02
    Air Quality, EPA, B. C. Jordan, November, 1977.

10.  Cost-Effectiveness Analysis of  the Proposed Revisions in the
    Exhaust Emissions Standards for New and In-Use Gas Turbine Aircraft
    Engines Based on  Industry Submittals, EPA AC  77-02, R. S. Kilcox  ' '
    and R. W. Munt, December, 1977.

11.  Cost-Effectiveness Analysis of  the Proposed Revisions in the
    Exhaust Emission  Standards for New and In-Use Gas Turbine Aircraft
    Engines Based on  EPA's  Independent Estimates, EPA AC 78-01, R. S.
    Wilcox and  R. W.  Munt,  February, 1978.

12.  Letter from D. W. Bahr  (GE)  to J. P. DeKany  (EPA) dated April 13,
     1977.  Subject:   Comments to  reference 5.

13.  "Telecom,  R. Munt  (EPA)  to D.  Bahr  (GE), December 7, 1977.  Subject:
    Technology  for  the Proposed  1981 Standards.

14.  Telecom,  R. Munt  (EPA)  to D.  Bahr  (GE) , December 16, 1977.  Subject:
    Technology  for  the Proposed  1981 Standards.

15.   Letter from D. W. Bahr  (GE)  to  E. Danielson  (EPA) dated March 21,
     1977.  Subject:   CF6 data.

-------
                                   122
                                 *
                             References  cont.
16.  A Petition from Rolls Royce,  Ltd.  for Modification  of  the Emis-
     sion Standards to Rolls Royce Spey Engines,  Rolls-Royce  DP314,
     March, 1977.

17.  Status of Rolls-Royce Emission Reduction Technology and  Pro-
     grammes Applicable to Newly Manufactured Engines  of Current
     Models, Rolls-Royce DP305, December, 1976 (Private  Data).

18.  Letter from A. Gray (Rolls-Royce)  to J.  P. DeKany (EPA)  dated
     January 28, 1977.  Subject:  Comments to reference  5.

19.  Comments by Rolls-Royce on the EPA Aircraft  Technology Assess-
     ment, Status of the Gas Turbine Program, December 1976,  Rolls-
     Royce DP311, February 1977.

20.  Additional Comments Related to the EPA Aircraft Technology Assess-
     ment, Status of the Gas Turbine Program, December 1976,  Rolls-
     Royce DP311 Addendum.1, May 1977.

21.  Letter from A. Allcock (W. K. Dept. of Industry)  to J. P. DeKany
     (EPA) dated February 17, 1977.  Subject:  Comments  to  reference
     5.

22.  Telecom, R. Munt (EPA) to R. Rudey (NASA), November 17,  1977.
     Subject:  JT8D NOx Control.

23.  Telecom, R. Munt (EPA) to R. Rudey (NASA), November 18,  1977.
     Subject:  NOx Control Technology.

24.  NASA Comments to draft NPRM, September 20,  1977.

25.  Letter from G. N. Frazier  (PWA) to C. Day (LMI),  December 15,
     1977.  Subject:  Estimated Economic Impact of Proposed EPA
     Emissions Regulations for Aircraft.

26.  Letter from G. N. Frazier  (PWA) to J. P. DeKany (EPA), April 11,
     1977.  Subject:  Comments  to reference 5.

27.  Telegram from D. F. Heakes (Dept.  of Transportation, Canada) to
     W. Oleksak (FAA) dated April 14, 1977.  Subject:   Idle Speed
     for certification of the Canadian Challenger.
    *
28.  Letter from G. Opdyke  (Lycoming) to N. Krull (FAA)  dated June
     30, 1977.  Subject:  ALF502 Data.

29.  Letter from G. Opdyke  (Lycoming) to J. P. DeKany (EPA),  April
     15, 1977.  Subject:  Comments  to reference 5.

-------
                                    123
                                 •

                             References cont,
30.   Letter from D.  Bahr (GE)  to R.  Munt (EPA),  dated  August 7,  1978.
     Subject:   CF34  Emissions  Data.

31.   Letter from D.  Bahr (GE)  to R.  Munt (EPA),  dated  February 8,  1979.
     Subject:   Fuel  Flowrates  at Various Idle Power Settings.

32.   Letter from D.  Bahr (GE)  to A.  J.  Broderick (FAA),  February 24,
     1978.   Subject:  Emissions Data for ICAO.

33.   Telecom,  R. Munt (EPA) to D. Bahr  (GE),  May 17, 1978.   Subject:
     Status of GE Low Emissions Programs.

34.   Telecom,  R. Munt (EPA) to D. Bahr  (GE),  October 20, 1978.  Subject:
     Double Annular  Combustor, Performance and Problems.

35.   Letter from M.  Sherwood (Rolls Royce) to R. Munt  (EPA) dated June
     2, 1978.   Subject:   Emissions Control Technology for RM211 and Spey.

36.   Comments  by Rolls-Royce on the EPA Aircraft Technology Assess-
     ment,  Status of the Gas Turbine Program, December,  1976,  Rolls-
     Royce DP311, ISSUE 2, June, 1978.

37.   Presentation by Rolls-Royce Representatives to FAA Personnel,
     December, 1978.  Subject:  Emissions Technology,  Idle Definition
     for Regulations, Compliance Procedure for Regulations.

38.   Memorandum to the Record, R. Munt  (EPA), April 3, 1978.  Subject:
     Report of Visit to NASA - Lewis Research Center.

39.   Results and Status of the NASA Aircraft Engine Emission Reduction
     Technology Program (NASA TM 79009) October, 1978, R. E. Jones,
     et al.

40.   Telecom,  R. Munt (EPA) to P. Goldberg (PWA), October 20,  1978.
     Subject:   Installation of the Vorbix and Airblast Cornbustors on
     the JT9D.

41.   Telecom,  R. Munt (EPA) to P. Goldberg (PWA), May 26, 1978.
     Subject:   Technology Status of Emissions Control..          '•

42.   Pratt and Whitney Aircraft Submittal to ICAO (AEESG), February
     21, 1978.  Subject:  Emissions Data.

43.   Submission by Pratt and Whitney Aircraft to EPA Docket OMSAPC
     78-1, Control of Air Pollution from Aircraft and Aircraft Engines,
     December 1, 1978.

44.   Submission by Rolls-Royce Ltd. to EPA Docket OMSAPC 78-1, Control
     of Air Pollution from Aircraft and Aircraft Engines (Rolls-Royce
     Document, DP347), November 1978.

-------
                                   124
                             References cont.
45.  Submission by Avco Lycoraing to EPA Docket OMSAPC  78-1,  Control  of
     Air Pollution from Aircraft and Aircraft Engines, November  30,
     1978.

46.  Submission by General Electric to EPA Docket OMSAPC,  Control  of Air
     Pollution from Aircraft and Aircraft Engines, November,  1978.

47.  Testimony of the EPA Public Hearing on Revised Aircraft Engine
     Emission Standards, Volume 1 and 2, November 1-2,  1978.

48.  Aviation Week and Space Technology, Vol.  110, No.  19, May 7,  1979,
     pp. 43.

49.  Aviation Week and Space Technology, Vol. No. 22, .May 28, 1979,
     pp. 46.

-------
                              APPENDIX A


                    EMISSIONS CONTROL TECHNIQUES


                         HC and CO Techniques <


Operational Control Techniques





     1.   Increase in Idle Speed - As engine power is  increased,  HC and


CO levels generally decrease as a result of higher temperatures and


pressures at the combustor inlet.  However, the NOx level may increase


because of the increased temperature in the combustor.   The increased


idle speed is limited on turbofan and turbojet  engines by the capability


of the aircraft brake systems as there is an increase  in thrust at idle.


This problem does not exist with turboprop (class P2)  engines as  the


thrust can be held nearly constant by properly  varying the propeller


pitch with engine speed.  However, there is an  attendant increase in


fuel consumption and noise with increased engine  speed.





     2.   Airbleed - Airbleed (of compressor air) is a means of in-


creasing the work load of an engine with, hopefully, the same result as


occurs by increasing-the idle speed (another form of work load),  yet


without the concomitant penalty of higher thrust  and its ensuing  braking


requirement.  To be effective, the engine must  increase its fuel  con-
                                                               i

sumption with the bleed to provide the necessary  energy for compressing


the extra air and to maintain the idle power.  Failure to do so will


cause  the engine to lose power and the emissions  to rise.

-------
                                  A-2

                               *




Fuel Preparation Control Techniques








     3.   Spray Improvement - Design changes to pressure atomizer




nozzles can lead to changes in the character of the fuel droplet size




distribution. Decreasing the flow number (equal to the fuel flow rate




divided by the square root of the injector pressure differential)




reduces the droplet size.  This in turn reduces the evaporation time and




strongly influences the amount of HC left unburned.  To a lesser extent,




the change in the evaporation rate affects the local fuel-air mixture




ratio and thus the local temperature which would likely affect the CO




and NOx levels.  This approach is not universally profitable, however,




as at very low combustor inlet temperatures, no degree of atomization




will improve the droplet evaporation for there is simply insufficient




heat available.








     Incorporation of this approach into a hardware system involves




changing both the pressure differential across the injector and the




orifice diameter as otherwise the fuel flow rate would be increased at




each power setting because of the change in pressure.  Changing the  '"•




pressure differential requires only a new set of valves and possibly a




pressure boost in the fuel pump.








     In addition, nozzle design changes intended  to optimize  the fuel
  •



spray  cone angle, and thus the distribution of fuel in  the primary  zone,




are  relatively easy to  incorporate  into a combustor.  Decreasing the




angle  of a wide  (richening the. mixture) angle spray cone reduces wall




wetting and  increases the  local equivalence ratio  to produce  a hotter

-------
                                  A-3
                               •



flame which in turn helps to reduce KG and CO.   Similarly,  widening the



spray angle reduces the equivalence ratio, providing a leaner mixture



which might be necessary in the case of an excessively rich mixture



(insufficient oxygen to burn the fuel).  There  is no impact on the



system hardware as only the fuel nozzle is changed and the  new one is no



more complex than the old.   The new heat release distribution, however,



may require changes in the liner cooling air.
        STD. FUEL NOZZLES
                                           NARROW ANGLE FUEL NOZZLES
                               GE CJ610
     4.   Airblast - The pressure differential that exists between the com-



pressor and the combustor is employed to achieve high velocity air through



a venturi system in the fuel nozzle.  This high velocity air is directed

                                                             ^

at the fuel stream as it comes off a lip.  The fuel is thus sheared



off and shattered into minute droplets, conducive to dispersion and
  •


complete evaporation.  The addition of the airblast air into the primary-



affects the stoichiometry and consequently it proves necessary to re-



distribute the airflow throughout the liner in order to reestablish the

-------
                                  A-A
optimal fuel-air ratio pattern.
     Success in. improving the combustion efficiency by utilizing this

technique has varied among the manufacturers depending upon the extent

to which the liner flow was optimized.  Also, it has been found that

NOx increases slightly at idle as a result of the better combustion ef-

ficiency.  At low power and especially in low pressure ratio engines,

the pressure differential across the injectors is reduced causing the

air velocity around the fuel injectors to be reduced.  Therefore, the

airblast effect on fuel atoinization tends not to be as effective at lotJ

power where the bulk of the HC and CO is formed.  The concept also tends

to be less effective in reverse flow annular combustors as the nozzle is

located so as not to be able to take advantage of the dynamic component

of the pressure.
 Conventional Pressure
 Atomizing Nozzle
Airblast Nozzle
                                P&WA JT8D

-------
                                        A-5
                                     «


           5.   Air  assist - In  the air-assist technique compressor air is



      diverted  and compressed externally, and then discharged around the fuel



      injectors.  This high velocity  air is directed through the fuel in



      jectors in  a manner similar  to  the airblast technique and achieves the



      sane  goals.  However, the  external compression provides high velocity



      air at all  powers  so this  technique may be expected to be more effective



      than  airblast  in controlling HC and CO at idle.







           The  use of air assist would have a large impact on aircraft hard-



      ware  systems because of the  requirement to bleed compressor air and



      compress  it externally with  an  auxiliary compressor.  The externally



      coEpressed  air is  more effective than the air of the airblast concept



      and so less is needed.  This then has a less marked impact on the



      stoichiometry  so that the  need  to redistribute the liner airflow is



      considerably lessened.
  Airblast
Air-Assist
      Fuel
JSI

                            JX1
                                                Far
                                                         Compressor
                                Burner
Turbine
        Air-Assisted, Airblast Fuel Nozzle



                           AiResearch TFE731 Concept
                              External

                             Compressor

-------
                                 A-6
                               •
                   .'-
     6.   Preinix(l)  - The basic idea is that HC and CO emissions often .


arise because of poor mixing within the primary so that while the


average equivalence ratio in the primary nay be acceptable (roughly


stoichiometric at idle), there are zones of excessively rich or lean


mixture, both of which lead to HC and CO production.  One way to prevent


this is to premix (and prevaporize) the fuel prior to the flame zone so


that the additional mixing time will lead to a more homogeneous mixture.


In order to prevent flashback of the flame, the premixing can be com-


promised a bit by keeping the local equivalence ratio above the stable


deflagration limit in the premix zone.  Upon entering the flame zone,


further mixing can occur, permitting combustion.  Although this can lead

to less than perfect mixing and thus reintroduce to a degree the


original problem, the HC and CO emissions are much improved because of


the partial mixing and total fuel evaporation in the premix zone.  The


excessively rich premix zone can lead to carbon deposition, however.




     NOx cannot be controlled by this approach unless total and lean


premixing occurs which directly leads to the flashback problem, making


premix for NOx control considerably more complex  (premix(2)).




     Implementation of  this scheme into an existing design can be


difficult in  that  the rather major combustor modifications must normally
 *Number  refers  to  one  of  two  different  degrees of control generally

  recognized  possible with this  concept.

-------
                                   A-7



be kept within the constraints of the existing envelope.   The more space


that is taken for the premix region,  the less that is available for

dilution and pattern factor adjustments.  Ideally, the combustor'would


be nade longer with the premix zone merely being tacked on to the

existing geometry (with some airflow adjustments).
PREMlXIfiS TU3E
                                   11.4%
12.3%          ".6%
                               P&WA JT8D
Air Flow Distribution Control Techniques
     7.   Advanced Cooling - High pressure ratio engines which operate

 at high corabustor temperatures require high levels of cooling air to

 control the temperature of the liner (the amount of cooling air required
                                                             \
 is even higher because the high pressure ratio causes the cooling air to

 be proportionally hotter and therefore less effective).  This cooling

 air, upon entering the liner, tends to quench the reactions of the

 burning fuel near the wall, especially that of CO   -»•   C0?.  Any

 advanced cooling technique which will provide the requisite cooling

-------
                                   A-8


                               *


effect while at the same time reducing the air needed may improve CO




emissions and possibly also HC emissions.   The key to its effectiveness




is the degree to which combustion, principally CO oxidation, is occuring




near the wall.








     The overall impact of such a revision is considerable for it




represents essentially a totally new combus.tor.  While benefits beyond




simple emissions control may be accrued (combustor of greater longevity) ,




the development cost is likely to be high.
                               Old
                                New
                        GE CF6 Combustor liner
      8.    Rich Primary (1)  - the  term "rich" applies to  the  stoichio-
 »               - - ' —" - •—™     '



 metry at the design  point (high power).   Such a condition  leads  natural-




 ly to near perfect stoichiometry  in the  primary at idle.   This results

-------
                                   A-9
                               4
in a very hot flame which is most conducive for evaporating and burning
the fuel despite the quite low pressure experienced at idle.   The hot
flame does leave considerable equilibrium CO which must be consumed by
proper temperature control (>1500°K)  in the'intermediate zone.


     The biggest difficulty with the  rich primary concept is that
because it is rich (excess fuel) at the high pressure high power condi-
tion, there is a strong tendency to produce smoke in the primary which
in turn must be consumed in the intermediate and dilution zones.  This
is not readily done so smoke control is usually done another way, by
running the primary with perfect or slightly lean stoichiometry, not
rich.  Thus, smoke control in this instance opposes HC, CO control.
     It is also possible to have excessive HC levels despite the favor-
able flame temperature if the mixing and fuel distribution is inadequ-
ate, thus leaving pockets of excessively rich mixture which cannot burn.
Proper spray characteristics and atomization are thus required.
                                   Secondary air admission
              Primary air
              admission \
          Svvirler          ~
          flow
          uuvv
SC^TT
                                            #    ®
                                .    f    r
                              Liner cooling air

-------
                                 A-10
                               •
     9.   Lean Primary (1) - As noted above, this approach

intrinsically produces low smoke at high power.   However, at idle the

mixture is even leaner.  If done properly, this  is beneficial because

excessively rich pockets are avoided, thus controlling HC, and the CO

level may be lower than in the rich primary case because the lower

flame temperature will result in a lower CO equilibrium level.  In any

event, the CO will have to be consumed in the intermediate zone.
     Difficulties with this approach lay in the possibility of exces-
sively lean pockets wherein the reactions may be quenched  (Excessive HC
and CO) and in flame stability and relight (especially at altitude).
Also, as this approach utilizes more air up front in. the primary, there
is necessarily less for use in the aft portions for cooling and tem-
perature profile control  (dilution).  This can have serious ramific-
ations for combustor and  turbine durability.
                                Secondary air admission
    Primary air
    admission \
Swirler  ^^fli
flow  -<>   fV
         Lean
                        15*?=
                         'Combustion
                              2one
      Fuel
      nozzle
                                 r    r
                           Liner cooling air

-------
                                 A-ll
                               *
     10.  Delayed Dilution - By delaying the introduction of dilution

air, a longer combustion zone at intermediate temperatures is provided.

This increases the residence time of the reactants which allows the CO

to C07 conversion to approach equilibrium and for unburnt hydrocarbons

to be consumed.  The temperature in the intermediate zone should ba,

however, low enough so that NOx formation rates are slow.  The dif-

ficulty lies in adjusting the air flow into the intermediate zone pro-

perly at all power settings so it is hot enough for CO consumption, yet

cold enough to prevent NOx, and still achieving flame stability, liner

durability, etc.
\000O O/
0 0 O (
c
«
> O 0 o
r


1 0 O O O 0
oc
DO

1
           Conventional Liner
Delayed Dilution Liner
                              Allison 250
Staging Techniques
    11.   Sector Burning - Sector burning is a circumferential fuel
staging technique designed to combine elements of the spray improvement
and rich primary control techniques (3 and 8) and at the same time not
affect in any way the combustor at high power (e.g., smoke from a rich
primary).  If the baseline combustor has a lean primary, then at idle

-------
                                 A-12
                               •


when the combustor is burning quite lean and at low flame temperature,  .

the combustion efficiency is poor, resulting in much HC and CO, because

of inadequate heat to vaporize the fuel and to stimulate the CO • -»•  C0~

reaction.  This problem is resolved by cutting off the fuel entirely  to

part of the combustor (usually about half) and injecting it with the

rest of the fuel into the remaining part of the combustor.  This has  two

beneficial effects:   (1) the pressure drop across the nozzle is neces-

sarily increased, improving atomization and (2) the.fuel/air ratio  is

increased (richened) so that a hotter flame exists, improving vaporiz-

ation of the fuel and enhancing  the CO  ->  C02 reaction.



     Hardware requirements include a split manifold, proper cracking

pressure of the valving in the nozzles, an additional valve in  the  fuel

control system to control  the sector burning  itself (with  an override to

avoid it entirely while in flight) , and a sensing device  to determine

flight vs. ground activity.  Changes in the nozzle  orifices may be

necessary to provide proper  fuel flow at  all  power, regardless  of  the

sector  (on or off at idle).
      The primary concerns with this system are the  reliability of the

 more complex fuel control system and the possible degradation of the
                                                              V

 turbine efficiency at idle (while sector burning) with an ensuing fuel


• penalty.

K.I n

n

Compressor

1
Burner
t

Turbine

.J
                                             Hom.il
                                            Operation
Fuel Sectored
  at Idle
                                GE CF6-50

-------
                                 A-13
                         NOx Control Technique
Air Flow Distribution Control Techniques
     12.  Quick Quench Primary - The idea here is to introduce the




intermediate air as close as possible to the upstreas dome or bulkhead




so as to minimize the extent of the primary zone.  This zone, operating




at high power near to the stoichiometric point, produces a very hot




flame (2600°K) well in excess of that needed to activate NO production.




The reaction time to equilibrate NO at this temperature is only a few




milliseconds so in order to avoid significant NO production, it is




necessary to introduce the intermediate air quickly to quench the NOx




producing reactions (temperature < 1800°K).  However, as the quench




temperature should still be in excess of 1500°K in order not to quench




the CO oxidation, great care is required to properly tailor the airflow.




The problem is that the quick quenching occurs also at idle and if tuned




to work correctly for NOx control at high power, it tends to quench  the




HC and CO consuming reactions at idle producing excessive low power




emissions.
f
0

O
o
O
o
O








o
o
o
o
o
o
o
o
o
























^J
c

u
£5
n
•~/
-^\
Q
































                          Standard
Quick Quench
                                GE.CFM56

-------
                                  A-14

                               *

     13.  Rich Primary (2)  - A sufficiently rich  primary  at  high power



will provide a cooler flame and a shortage of oxygen,  both of  which will



discourage NO formation.   As there will be further reaction  in the inter-



mediate zone where more air is available to burn  the  excess  fuel (and



create MO), it is necessary to carefully tailor the airflow  in order



to maintain the cool flame throughout.  This approach is  not satis-



factory, however, because of the high smoke levels and the generally



poor low power emissions (HC, CO) which arise from the excessively rich



primary which occurs at idle.
   14.    Lean Primary (2) - The lean primary zone is achieved by intro-



ducing a larger percentage of the total combustor airflow into the



primary zone.  In sufficient amount, this creates a very lean, and



therefore, cool flame which prevents the formation of NOx by lowering



the N~  ->  NO reaction rate.






      Several problems are created, however, by this procedure.  First,



the large amount of  air  into the primary creates a shortage of air



downstream for use in cooling and temperature profile control  (dilution).



This  may adversely affect the durability of the liner (cooling) and  the



turbine downstream  (temperature profile).  Second, HC and CO-.emissions
                                                             }-


are very much affected adversely.  Too  cool a flame at high power may



quench  the CO oxidation  as well as  the  NO production.  More importantly,



however, is  the  fact that being lean at high power implies a very lean



 flame at low power  (e.g., idle) so  that under those adverse conditions



 of low  temperature  and pressure,  the fuel may not vaporize, the HC  and  CO



 oxidation  reactions  will proceed  too slowly, and in  the  extreme case,



will cease (flame  instability).   This also creates altitude relight


problems.

-------
                                  A-15
                               •

Fuel Preparation



    15.   Spray Improvement - The spray improvements  discussed  in (3)

also affect NO production.   Better atonization eliminates droplet

burning (locally stoichiometric and hot)  and the spray angle affects

the fuel distribution (local hot spots).   Better atonization is univer-

sally good for all pollutants, whereas a change in the spray angle may

adversely affect one or more pollutants while favoring the others, or

it may favor all.  The outcome depends on other factors in the  primary

zone, specifically the initial fuel-air distribution, the airflow

pattern through the doae and the amount of cooling air.
    16.   Premix/Prevap - Fuel and air are mixed in a prechamber prior

to entering the primary combustion zone.   This prefixing allows combus-

tion to occur at a much leaner condition where NO formation rates are

slower.  This technique is most applicable to high pressure ratio engines,

which produce the high combustor inlet temperatures required to sufficently

vaporize the fuel.  With the premix concept careful attention must be.--,

given to the prechanber exit conditions.   Exit velocities of the fuel-air

mixture must be high enough at all power levels to prevent flashback

which is very damaging to the liner and the nozzle.  Also, in creating

a uniform lean primary zone, stability may be a problem leading to alti-

tude flaiaeout and difficulties in relighting.  Low power emissions(HC,

CO) may be a problem if adequate mixing and vaporization do not occur

at idle where the conditions are much less favorable.

-------
                                  A-16
                               0

     The prersix concept requires a significant change to the combustor

liner geometry since the premix chamber must be included in the  com—'

bustor.  This may lead unavoidably to a longer overall combustor,  thus

co najor changes in the engine configuration.  The alternative,  to

exchange some of the combustor length in  the dilution zone for the

prenix mechanism, also can lead to complications because there is  then

less space available to tailor the temperature profile at the turbine

ip.let.  This compounds the already difficult tailoring job precipitated

by the shortage of dilution  air arising from the lean (excess air)

primary (see 14).
                                              PREMIX
                                              TUBES 13 LOCATIONS
      Premix coinbustor as seen on an axially staged(18)  cornbustor

                               P&WA JT9D-7                    :-


 Staging Techniques
     17.  and 18.      Fuel staging - The combustor is divided into two

 regions, each having its own fuel injection system.  These are termed

 the pilot stage and the main stage.  At low power, fuel is supplied only

-------
                                 A-17
                               *



to the pilot stage, thereby allowing a much higher local fuel/air ratio



than would be possible if the fuel were distributed throughout the



combustor.  This is basically the rich primary approach (8).  This



mixture is then able to burn hotter, enhancing droplet evaporation



(aiding HC burning) and CO oxidation.  Some form of fuel preparation



control (3 or 4) would also be incorporated.







     At high power, the bulk of the fuel is injected into the main stage



which designed to burn lean for NOx control (concept 14) and low smoke.



Flame stability is provided by the primary stage which is still burning



rich.  The pollutants produced by the primary at high power (CO and



smoke) should be consumed when diluted by the much larger main stage



flow.







     Staging requires two manifolds and two fuel injection  locations and



adds to the complexity of the fuel supply system and the fuel control.



The combustor liner is also more complex with additional cooling and



temperature profile problems.                                        - •







     There are two basic types of fuel staging here, radial (17) and



axial  (18).  In the former case, the stages are in parallel and fit more



readily within a short combustor volume.  In the latter case, "the  stages



are in series.  Its primary advantage is that the upstream  primary stage
«


is.better located  to act as a flame  stabilizing agent on the main  stage



which may then be  run more lean.

-------
                                    A-18
\
                                                     Pilot z:nt
                                            Pilot zone     swirlsr
         f'Jin zont
         swirlsrs
                                                                  Main zon»
                                                                  fuel Injector
                                                                              t:
       Radial Staging (17)
            GE CF6-50
Axial Staging  (18)
    P&WA JT9D-7
       19.   Variable Geometry - Variable geometry (or air staging) provides

   airflow control of the primary and intermediate zones such that the

   stoichiometry provides stable efficient combustion with a minimum  of NOx

   production over the complete operating range of the engine.  Air enters

   the combustor through holes equipped with a mechanism (usually a sliding

   ring) that meters the airflow in proportion to the fuel flow. - With this

   system the primary zone fuel air ratio can be controlled to be soichio-

   metric at idle power for HC and CO reductions, and to be lean  (but

   stable) at high power for NOx reductions.  However, as there is no flame

   stabilizing mechanism here, the degree of lean burning, and hence  the

   NOx reduction, is limited.                                    :
        This system has a number of operational drawbacks, primarily the


   reliability of the mechanical system  in  such a severe  environment which

   is a safety issue.  However, the notion  of moving mechanical systems in

   severe environments is not new  to gas turbines;  variable  pitch com-

-------
                                 A-19
                               *

 pressor  stators and variable  turbine nozzle guide vanes do exist.  Failure

 of  the mechanism, however, must not prevent the engine from providing

 adequate operational performance over its flight regime.
 Catalysis


                                                                     «. *
     20.    Catalysis  -  Catalysis  is  a  process by which a special  sub-
                                                                     • :*•*
 stance,  usually a solid  substrate,  causes  the acceleration of a  chemical

 reaction while not being permanently  affected itself.  Catalysis is

 often used on current  automobiles  to  limit the emissions of HC and CO by
                                                              r
 the placement of the catalyst  in the  exhaust gas so  that these pol-

'lutants, which are products of incomplete  reaction in the cylinders, can

 be consumed.
      In an aircraft engine,  however,  the catalyst would have  to  be

-------
                                 A-20
                               *

placed in the combustor proper.  This then permits  the  reaction to

proceed under uniformly lean conditions, thereby giving a cooler flame

and less NOx production while still consuming the KG and CO through the

enhancement of the reaction rate.
     Primary development problems are getting the catalyst to work

quickly during the warm-up period, prevention of poisoning of the

catalyst, prevention of mechanical wear on the catalyst material,

prevention of excessive pressure loss through the catalyst bed,  and

prevention of flashbacks into the premixed air-fuel upstream of  the

catalyst.  Recent investigations suggest that, if used for NOx,  a

catalyst would probably have to be used in conjunction with variable

geometry in order to keep the stoichiometry within limits acceptable

to the catalyst.

                                                       Catalyst
                 Catalyst Combined with Axial Staging

                           General Electric

-------
                                 A-21
Water  injection









     21.   Water  Injection - Water injected into  the primary  zone of  the




combustor results  in  a  lower primary zone temperature. This  lower




pri-zary  zone  temperature in turn results in a  significant  reduction  in




NOx  as a result  of  the  lower N_ -> NO reaction  rate.  However,  if the




 temperature is reduced  too much, an increase in  CO occurs  due  to the




quenching of  the CO oxidation.  Water  flow rates equal to  that of  the




 fuel flow rate are possible giving a 50% reduction in the  NOx  level.









      The use  of  water injection presents a number of problems:  (1)  The




 increased aircraft weight due  to the mass of water carried may reduce




 the  useful payload of the aircraft.   (Usually, hox^ever,  water  injection




 results  in increased  thrust, and hence the payload possibly  can be




 increased if  takeoff  performance is  the critical factor);  (2)  Higher




 fuel consumption is required to maintain turbine inlet temperatures; (3)




 Precautions must be taken  to prevent  ice formation in the  water in-




 jection  system for operation at ambient temperatures below the freezing




 point of water;  and (4) water  must be  demineralized  in order to prevent




 turbine  blade corrosion and pitting.   The use  of tap water results in




 substantial  turbine deterioration  and  .thus  compromises safety  and  engine




 reliability.   Also, demineralized water can  be very  expensive  (over




•SO.30 per  gallon)  depending upon  the  location.  Logistics  for  deraineral-




 ized vater may be  a problem also,  especially for those aircraft using




 snaller, more remote  fields.

-------
                           A-22
                                     WATER
     FUEL
  WATER
DISCHARGE
        CF6 COMBUSTOR
CF6  SPRAY NOZZLE

-------
                               A-23
                              *
New Procedures



     22.   Selective Azirauthal Burning (SAB)  - This control technique for

HC and CO is an offshoot of the sector burning concept (11).   The two

drawbacks to sector burning are recognized as (1)  fuel penalty while in

operation as a consequence of the severely asymmetric loading on the

turbine,  and (2) the potential hazard arising from a malfunction that

might cause sector burning in flight.  At higher power, the turbine

would be  damaged,  and at flight idle, the engine might be unable to

accelerate.   SAB removes both of these difficulties.



     The  essence of the method is to reduce the number fuel nozzles

in operation at idle so as to improve the atomization of those in use

and, especially, to improve the local stoichiometry.  This is, of course,

precisely the procedure and rationale for the sector burning idea.  In

this case, however, the distribution of those nozzles firing and those

off is more or less uniform around the annulus.  For instance, in the

CF6-50, sector burning would include a solid 180  sector (15 nozzles)

off and the other 180  sector on.  For selective azimuthal burning, on

the other hand, a typical arrangement might be to distribute 20 firing

nozzles into 5 segments of 4 each so that each segment will be separated

by 2 off nozzles [ie, 4 on - 2 off,  5 times around].  Many other arrange-

ments are possible and the optimum is chosen by the competing demands of

emissions control performance, operational performance (eg, relight),

and mechanical performance (eg, pattern, factor).

-------
                                A-24
     This method eliminates the problems of  sector burning because it




provides sufficient symmetry around the annulus.  Thus,  at idle,  the




turbine efficiency and acceleration are not  noticeably  degraded,  and




at low power above idle, the pattern factor  is  not so poor as to  cause




significant turbine damage.  It follows then that SAB can  be used




successfully in flight, thus removing the need  for much of the complex




plumbing and the failsafe mechanism needed to prevent a malfunction from




leading to inadvertent sector burning in flight.









     There is, of course, a drawback to this procedure:  it is not as




effective as sector burning in reducing HC and  CO.   There  are two reasons




for this.  First, in order to provide an acceptable  temperature distribution




for the turbine, fewer nozzles can be turned off.  Hence the stiochiometry




and atonization quality are comprimised.  Second, quenching of the reactions




always occurs at the boundary between a reaction zone and  an adjacent,




cool airflow.  Sector burning has only two such boundarys, whereas SAB has




several, the number depending upon the geometry (eg, for the 4-2 case




mentioned above, there are 5 such quenching boundarys).  There would be,




therefore, a motivation towards the minimum number of quenching boundaries




and towards fewer nozzles  in operation at idle.  This would be nothing




more than sector burning.  The practical limit  is the point at which the  •-•




drawbacks of sector burning come into play,  that is, where SAB can no




longer be used in flight because of possible turbine damage or failure




to accelerate, or where the degradation of the  turbine  efficiency leads




to significant fuel penalty.  In fact, if the method were to be used in




flight on a normal basis,  then there are other  performance considerations




that weigh on the selectionof the actual geometry.   The system must

-------
                                A-25
(1)  provide stable combustion over flight envelope, (2) be able to




relight over sarae envelope, and (3) be able to accelerate front starting




power (sub-idle), as well as (4),  accelerate from flight idle.  .

-------
APPENDIX B




ENGINE DATA

-------
Engine: CF34. Thrust(KN) PR BR" S/V'(ra ) Idle
Baseline
Idle
Approach
Climbout
Takeoff
. 40
P T M M,
(atm) (°K) (Kpjs) (Kg/hr) f/a
3.1 447 4.0 173 .0119
430
1230
19.5 1480
19.5 6.4%
El
Comb .
Ineff. HC* CO* NOx* Sk
.0487 28.2 104.8 2.2
.0018 0.2 6.9 3.1
.006 0 ' 2.4 11.2
.0004 0 1.9 14.2 20
EPAP 53.1 205.0 24.9
Sector Burning at Idle " •
Idle
Approach
Climbout
Takeoff

Idle
Approach
Climbout
Takeoff
173**
.0146 6.7 38.1 3.3
20
EPAP 12.7 80.0 27.0
•
•
                                                                                                           w
. .*EIs estimated  from EPAP values.
**Assumed unchanged.

-------
Kiip. 1 UK : I'.
Mocl.PFRT
Idle
Approach
Climbout
Takeoff
•>!',(, Thrust- (KM) TK HU S/V(m )
IO/
!'. T M M .
(atm) (°ib (KK/S) (Kjjlir) f/a
3.6 463 360
10.6 617 1087
21.9 762 3042
25.6 779 3758
:,">.(. TJ.U
Comb .
Tncff. He: CO
.0189 8.0 51.7
.0013 0.4 4.0
.0003 0.1 1.0
.0002 0 1.0
EPAP 12.0 79.5
Sector Burning at Idle (15 of 20)
Idle
Approach
Climbout
Takeoff
360*
.0083 0.8 32.6
EPAP 1.5 51.7
Sector Burning at 6% Idle (15 of 20)
Idle
. Approach
Climbout
Takeoff
400*
.0057 0.3 23.4
U.le
•'('1 0">l I 1 i in)
F.I
NOx Sk
3.5
9.3
20.6
23.9
42.8
3.5
»
w
i
u>
42.8
4.3
                                                            EPAP
0.9     42.0     43.5
*Based on full annular performance.  It is understood that with sector burning the turbine efficiency
 may be degraded at idle to the point that additional fuel would be required to maintain power.

-------
Engine: CF6-32 ' Thrust (KN) PR

Idle
Approach
Climbout
Takeoff
145
P T.. M . M.- Comb.
(a Cm) (°K) (Kg'7s) (Kc/hr) f/a InefE.
2.6 427 443
9.7 599 1584
21.5 749 . 4772
23.1 766 . 5779
.0482
.0014
.0002
.0002
EPAP
Sector Burning Projection .
Idle
Approach
Climbout
Takeoff
443**
.0055
EPAP
Double Annular Projection
Idle
Approach
Climbout
Takeoff
.
.0117
.0046
.0005
.0004
BR

nc
36.1*
0.2
0.1 '
0.1
48.1
1.3*
2.0
2.0
0.6
0.1
0
S/V(m
24.
ET
CO
73.3*
5.5
0.6
0.6
102.1
18.7*
29.8
42.9 '
17.7
1.8
1.6
~A) Idle
8 4%
NOx Sk
4.3
11.0
29.0
33.2.
64.1


3.7
8.6 ' •
14.0
16.3 .
                                                                                                           td
                                                                                                           I
                                                          EPAP         3.2     72.6    35.6
 *Estimated from EPAP values.                            .
**Based on full annular performance.  It is understood that with sector burning the turbine efficiency
  may be degraded at idle to the point that additional fuel would be required to maintain power.

-------
 Engine:   CF6-.6D
Thrust(KN)
PR
BR
S'/Vdn'1)
                                                   •174.8
              24.5
       5.9
          24.8
Idle.
             3.34%
                                                                                  El
Production (atm)
Idle
. Approach
Climbout
Takeoff
2.7
24.5
T. M
(°K) (Kg?S)
435 10.1
779 71.2
"s
(Kg/hr)
483
1728
5206
6304
Comb .
f/a Ineff.
.0132
.0244
.0489.
.0014
.0002
.0002
HC
36.0*
0.2
0.1
0.1
CO
76.9*
5.5
0.6
0.6
NOx
4.6
12.1
32.4
39.7
Sk
16
                                                             EPAP
                                                                       43.3
                              96.5
                        65.7
 Sector  Burning  at  Idle
Idle
Approach
Climbout
Takeoff
483**
.0056
EPAP
Double Annular Prelection
Idle
Approach
Climbout
Takeoff
•
.0112
.0040
.0005
.0004
EPAP
1.1*
1.8
1.9
0.6
0.1
0
2.8
19.9*
26.1
41.0
14.8
1.8 .
1.6
61.5
4.6
65.5
4.0
8.7
15.6
18.1
35.2
»
w
i
Ln
 *Estimated from EPAP values.
**Based on full annular performance.  It is understood that with sector burning  the  turbine efficiency
  may be degraded at idle to'''the-point that additional fuel would be  required  to maintain power.

-------
Engine:  CF6-50C
Thrust(KN)
PR   UR
S/VCnf1)  Idle
                                                       224.2
              29.8  4.4  27.2
                     3.4%
P3
Production (a tin)
Idle
Approach
Climbout
Takeoff
2.9
11.7
25.9
29.8
(O t/\
Iv/
429
630
786
820
H
(KK7s)
13.8
47.6
92.1
103.0
(Kgi'hr)
548
2394
7034
8554
Comb *
f/a Ineff.
.0110
.0140
.0214
.0231
.0765
.0010
.0001
.0001
11C
59,3*
0.2
0.1
0.1
CO
109.4*
3.9
0.7
0.7
NOx Sic
3.5* 13
12.0
29.1
33.9
                                                            EPAP
              63.0  119.5
Sector Burning at Idle with Nozzle Modification
 *Estiraated from EPAP values.
**Based on full annular performance.  It is understood that
  may be degraded at idle to the point that additional fuel
                 60.8
Idle
Approach
Climbout
Takeoff
548**
.0079
EPAP
Double Annular
Idle
Approach
Climbout
Takeoff
•
.0103
.0028
.0005
..0004
EPAP
0.7* 31.4*
1.0 37.1
1.8* 37.7*
0.5 .10.1
0.1 1.8
0 1.6
2.4 . 49.8
3 . 5*
60.8
4.0*
10.0
19.1
25.5
44.7
                                                                                                           w
                                                                                                           I
     with sector burning the turbine efficiency
     would be required to maintain power.

-------
Knj;ine:   JT3U-7
Thrust(KN)
IVi.!.
                                                                    I. !. j
J'.R
                                                                                      Kl.*
1'.. T M M, Comb.
Production (at:m) (°K) (Kp'/S) (Kj',/hr) f/u lm>ft.
Idle
Approach
Climbout
Takeoff
460
1400
3720
4525
.1561
.0043
.0011
.0008
IIC
149
2.6
0.8
0.6
CO
119
8.5
1.5
0.9
NOx
1.4
4.6
9.4
12.0
Sk
	 n
                                                               EPAP
                     356
    294
31
Aerating Nozzle/Leaner. PZ_Combustor
Idle
Approach
Climbout
Takeoff
           •0788      66.0   94.1    2.3
           .0026       1..2    6.7    7.8
           .0005       0.3    1.2   16.0
           .0004       0.3    0.7   20.3
                                                               EPAP
                    m*m&*nauiHa*iL»*C*»f) ***vt*'tffi*rru****.wv**Ki*w.
                     158    232     53
                                                                                                                 w
                                                                                                                 i
Idle
Approach
Climbout
Takeoff
*EIs estimated from earlier  data.  '

-------
Engine: JTRD-9 • Thrust (KN) PR
Production
Idle
Approach
Climbout
Takeoff
64.5 16.9
p ** T** . M . M, Comb.
(atiu) (°K) (Kg'?S) (Kg7hr) f/a Ineff.
2.7 404 476
6.6 .530 1072.
14.7 673 • 3044
16.9 708 3744
.0168
.0037
.0008
.0007
EPAP
Aerating Nozzle/Rich PZ Combustor Projection
Idle
Approach
Climbout
Takeoff
•
.0053
.0010
.0003
.0002
• EPAP
Vorbix Projection
Idle
Approach
Climbout
Takeoff

.0049
.0013
.0022
.0015
EPAP
BR
1.04
HC
10.0
1.7
0.5
0.5
35.1
2.2
0.3
0.2
0.2
7.8
0.26
0.14
0.32
0.15
1.6
S/V(m
25
El
CO
34.5
9.4
1.7
~~LJL»_-
124.5
14.5
3.4
0.6
0.2
51.3
20.0 '
5.2
8.3
5.8
88.0
~1) Idle
.2 7 . 0%*
NOx Sk
2.9
5.6
14.2
17.9 23
. 52.2
3.3
6.4
16.0
20.3
59.1
2.4
• 5.3
8.6
11.2
36.0
»
w
i
CO
 *Quoted value, unrealistically high.
**Estimates

-------
Engine: JT8D-17 Thrust (KN) PR
1'roductlon
Idle
/von roach
CllTnhoupn_ .
Takeoff
71.2 17.
*
P T M Mf Comb.
(a tin) (°R) (KR'/S) (Kg/hr) f/a Ineff.
531
1275
3588
4482
.0160
.0037
.0010
.0008
EPAP
Aerating Nozzle/Rich PZ Combustor
T.rllP
Approach
Climbout
Takeoff
Production
Values
.0049
.0010
.0003
.0002
EPAP
Advanced Vorbix (II-9) Rig Test
Idle
Approach
Climbout
Takeoff
2.87 412 14.2 514 .0100
6.83 535 30.9 1247 .0112
15.08 678 60.0 3553 .0164
17.40 714 67.1 4406 .0182
.0046
.0011
.0019
.0013
EPAP
BR S/Vdrf1) Idle
4 0.
HC
10.2
2.0
0.8
0.7
37.3
2.1
0.3
0.2
0.2
7.6
0.25
0.14
0.32
0.15
1.6
99
CO
31.0
8.5
1.0
0.7
112.7
13.7
3.2
0.6
0.2
49.4
18.9
4,9
7.8
5.5
83.1
25.2 7.0%*
El
NOx Sk
3.3
6.1
15.2
19.2 24
60.1
3.7
7.0
17.3
21.9
68.4
2.7
5.8
9.3
12.1 27
41.0
*5'C
»
w
1
vO
 ^Quoted value, unrealistically high.
**EIs estimated from EPAP values.

-------
Engine: JT
(c
Production
Idle
Approach
Climbout
Takeoff
8D-17 Thrust (KN) PR BR S/V(m ) Idle
/ 1 « Z
17.4 0.99 25.2 . 7.0%*
El

P. T M M Comb.
(atm) (°K) (Kgfs) (Kg/hr) f/a Ineff. HC CO NOx Sk


Advanced Vorbix (P&WA proprietary configuration)
Idle
Approach
Climbout
Takeoff
Production
Values
.0075 3.0 22.2 3.3
.0012 0.3 4.5 8.0
.0008 0 3.8 12.2
.0005 0 2.4 14.3
EPAP 10.0 85.9 53.3
Idle
Approach
Climbout
Takeoff
'

»
i
H-*
o
*Quoted value, unrealistically high.

-------
    .TT9D-7
Thrust(KN)
PR
BR
S/VOt."1)
                                              205.3
              21.4
        5.2
         19. 3
                                                                              El
P3
Production (a tin)
Idle
Approach
Climtjourr
Takeoff
3.6
8.8
19.1
21.4
(5l
447
588
736
M
20.6
43.7
81.0
»^LL
780
2109
6010
Comb.
f/a Ineff.
.0105
.0134
.0206
.0360
.0013
.0004
. OOQ4
HC
26.4
0.6
0.3
0.3
CO
57.0
3.3
0.4
NOx
3.1
7.4
31.6
Sk
4
4
                                                        EPAP
                    45.4
             98.5
             .61.8
Aojv\M m» ^ryyrl f/Illrh P7, CnmhnSf fT*"
Idle
Approach
Climbout
Takeoff

.0056
.0013
.0004
.0004
EPAP
Vorblx (S27K)
Idle
Approach
Climbout
Takeoff

.0038
.0029
.0004
.0003
EPAP

2.9
0.6
0.3
0.3
5.7
1.0
0.5
0.1
0.1
2.1

13.2
3.3
0.4
0.4
24.6 .
12.8
10.8
1.2.
1.0
30.2

2.9
7.4
23.1
30.8 <20
47.4
2.9
4.7
11.6 '
13.8 30
26.2
estimated from EPAP value.

-------
Engine: JT9D-70 Thrust (KN) PR
Production
Idle
Approach
Climbout
Takeoff
.228 24.2
P.* T * . M M Comb.
(a tin) (°K) (Kg?S) (Kg/hr) f/a Ineff.
4.1 465 853
10.0 612 2449
.21.6 764 ' 7199
24.2 793 8791
.0228
.0007
.0002
.0002
EPAP.
Aerating Nozzle/Rich PZ 'Combustor •
Idle
Approach
Climbout
Takeoff
•
.0044
.0007
.0002
.0002
EPAP
Vorbix Projection
Idle
Approach
Climbout
Takeoff
. •
.0031
.0026
.0003
.0003
- 	 ... EPAP
BR
4.9
HC
12.0
0.3
0.2
0.2
20.0
2.0
0.3
0.2
0.2
3.8
• 0.9
0.4
0.1
0.1
2.0
S'/Vdif1
KI
CO
53.0
1.7
0.2
0.2
87.5
11.4
1.7
0.2
0.2
20.0
10.1 '
9.5
0.9
0.8
26.3
) Idle
n
NOx Sk
3.0
7.8
25.6
31.6 8
54.3
2.9
7.8
21.7
28.9 <10
48.5
3,3
5.8.
14 . 5
17.4
35.2
»
i
h-*
hO
*Estimated

-------
Engine: .TTRn_?nq • Thrust (KN) PR • BR • S/V(m ) Idle

Idle
Approach
Climbout
Takeoff
85.6
PY T M M
(a tin) OO (K!..,'?S) (KR/hr) I/a

19.2 1.62 25.2 7%*
El
Comb .
Incff. I1C CO NOx Sk

Aerating Nozzle/Rich PZ Combustor Projection .
Idle
Approach
Climbout
Takeoff

Idle
Approach
Climbout
Takeoff
544
1265 •
3511 '
19.2 . 4355
0.74 10.7 3.4
0.12 2.3 7.9.
0.02 0 16.7
0.01 0.9 21.3
j
EPAP 2.2 33.6 54.9 15
•

                                                                                                               w
                                                                                                               I
^Quoted value, unrealistically high

-------
Engine:  M45H-01
Thrust (KN)     PR
BR
S/VCm"1)
                                                         32.4
              16.9   3.0
        23.75
Idle
                                                                                     El
*3
Production (atm)
Idle
Approach
Climbout
Takeoff
3.0
6.5
14.6
16.9
rib
424
541
693
723
(Kg/SS)
5.24
10.8
21.2
23.8
Mf
(Kg/hr)
191
526
1498
1793
uomoi
f/a Ineff.
.0101
.0135
.0196
.0209
.0935
.0183
. 0024 •
.0021
HC
59.5
7.4
0.7
0.8
CO
178.4
51.0
7.9
6.2
NOx Sk
1.5
3.6
9.3
11.5 46.3
  Double Blown Ring
                                                                 EPAP
                    162.4   526.0  31.2
Idle
Approach
Climbout
Takeoff
200
508 .
1444
1753
.0222
.0043
.0009
.0006
EPAP




•
10.7
1.0
0.2
0.2
30.1
55.5
14.7
3.0
2.0
169.9
2.1
5.1
10.9
13.1 12
37.0

* Normal minimum idle is 7.6%

-------
F.iiK inc:   Spry Mkr>!>5
Thrust(KN)
PR
BR
S/V'dif1)
                                                    • 43.8
               16.1
        1.0
         38. 7
Id.le
                                                                                    El
Idle
Approach
Climbout
Takeoff
2.1 388 6.86 341
7.0 546 22.2 793
14.2 667 39.. 5 2126
16.1 698 43.3 2606
RAB
Idle
Approach
Climbout
Takeoff
301
785
CVS
Idle
Approach
Climbout
Takeoff
305
785

.0138
.0099
.0150
.0167
.141
.0118
.0005
.0048
EPAP
.0122
.0098
.0235
.0029
.0008
.0008
EPAP
.0124
.0098
.0380
.0029
.0008
.0008
EPAP
130.0
8.3
0.5.
5.1
441
11.4
1.7
0.1
0
36.1
24.3
2.0
0
0
75.6
117.7
• 20.0
0
1.1
420
57.4
4.9
3.9
4.3
186.1
72.0
5.1
3.6
3.4
232.0
0.9
5.9
14.7
19.0
49.5
3.4
7.9
14.0
16.1
55.2
3.1
8.2
13.7
15.4
54.2
»
i
i — *
01

-------
Knr,lm>: Spcy MU511 Thrust (KM) PR
Production
Idle
Approach
Climbout
Takeoff
50.7 19.9
P
P T_ M Mf Comb.
(atin) (°I() (Kg'7s) (Kg/hr) C/a Incff.
2.2 407 7.5 401 .0149
8.0 575 23.6 998 .0117
17.1 700 47.2 2619 .0154 '
19.9 734 52.4 3202 .0170
.094
.011
.0016
.0012
EPAP
RAB
Idle
Approach
Clirabout
Takeoff
370 .0137
990 .0116
.0165
.0002
.001
.0009
EPAP
CVS .
Idle
Approach
ClimbouC
Takeoff
377 .0140
900 .0116 •
.0355
.0022 •
.0008
.0005
EPAP
HR
0.64
HC
76.7
7.2
1.3
1.0
278.4
6.7.
1.4
0
0
23.0
22.9
1.6
0
0
75.5
S/V(m •*-)
38.7
El
CO
117.4
20.3
2.1
1.8
435.8
46.3
3.3
4.3
4.1
161.6
67. Z
3.6
3.4
2.3
229.0
Til IP
Min.
NOx Sk
1.1
7.9
19.2
23.3
68.1
3.8
9.1
16.2
18.8
68.2
1.1
9.4
15.5
17.5.
58.0
w
 I

-------
Elaine: KB'211-22IJ
1' T M Mf
Phase I (ntiii) (°K) (Kg?S) (Kg/hr)
Idle
— Approach
Climbout
Takeoff
3.6 446 18.1 627
10.6 616 46.1 2007
22.1 752 83.2 5555
25.0 781 91.5 6716
Phase II
Idle
Approach
Climbout
Takeoff
- 571
1989
5550
6712
Phase- II with Sector Burning
Idle
Approach
Climbout
Takeoff
568
Thrust (KN) PR
187 25JD
Comb.
f/a Ineff.
.0096
.0120
.0185
.0204
.100
.010
.001
.001
EPAP
.00875
.0120
.0185
.0204
.0131
.0007
.0005
.0004
EPAP
.0087
.007
Brt
5.0
lie
86.8
5.8
0.9
0.8
134.6
5.6
0.3
0.4
0.3
8.3
2.54
S/V(m )
20.11
CO
104 . 9
21.1
1.6
1.4
172.3
35.0
.1.9
0.7
0.6
49.6
19.6
Idle .
Min.
El
NOx Sk
2.3
8.2
25.4
33.2
51.9
4.3
12.4
29.0
34.3
61.7
5.5
                                              w
                                              I
EPAP
4.2
28.8
64.0

-------
Engine: K.15m-53!> Thrunr(KN) PR
Phase II
Idle
Approach
Climbout
Takeoff
142 19.3
P. T M M Comb.
(atm) (°IO (Kgfs) (Kg7hr) f/a Ineff.
3.1 424 15.8 544 .00955
8.3 574 36.8 1561 .0118
17.0 701 65.0 4340 .0188
19.3 727 71.6 5305 .0206
.022
.001
.0007
.0006
EPAP
Phase II with Sector Burning
Idle
Approach
Climbout
Takeoff
540 .00947
.011
EPAP
Phase III with Quick Quench
Idle
Approach
Climbout
Takeoff
539 .00946
.009
.002
.001
.001
EPAP .
BR
HC
11.1
0.28
0.46 .
0.41
19.1
4.9
8.9
0.84
0.55
0.49
0.50
2.5


CO
52.2
3.4
1.1
1.0
90.0
30.8
54.7
37.2
5.3
2.0
2.1
67.5
S/V(m ) T<11o
20.11 M.in.
El
NOx Sk
4.3
9.3
21.4
25.0
49.0
5.4
51.3
3.9
6.3
11.8
13.9
30.3
w
 I
CO

-------
Engine: RB211-524
4
P T M M
Phase I (a tin) (°il) (Kg'?S) (Kgjhr)
Idle
Approach
Climbout
Takeoff
3.7 453 19.7 661
11.3 629 50.9 2498
23.9 771 94.4 6684
27.2 801 104.1 8120
Phase II
Idle
Approach
Climbout
Takeoff
609
2477
6677
8144
Phase II with Sector Burning
Idle
Approach
Climbout
Takeoff
604
Thrust (KN)
218
Comb .
f/a IneEf
.0093
.0136
.0197
.02167
.093
.009
.0007
.001
EPAP
.00854
.0135
.01966
.02165
.011
.0007
.0004
.0002
EPAP
.0085
.0058
PR
27.2
11C
79.8
5.8
0.7
1.0
110.4
4.5
0./4
0.3
0.1
6.0
2.1
BR
4.5
CO
99.8
17.8
0.7
0.8
145.1
.30.7
1.7
0.6
0.5
39.0
16.9
S/VCm"1) Idle
20.11 Min.
I'M
NOx Sic
2.5-
9.1
30.2
40.5
61.4
4.4
13.6
32.1
38.3
68.0
5.5
EPAP
3.1
22.4   70.2

-------
Engine:  Olympus 593
Thrust (KM)   PR    BR   S/V(m~
                                                          171
             15.5
0
                                                                                                    Idle
     4.7%
P. T M Mf Comb.
Production (atm ) (°R) (Kgc?S) (Kg/hr) f/a Ineff.
Idle
Descent
Approach
• Climbout
Takeoff*
Afterburner **
1140
2360
4550
. 9100
15.5 12700
10000
.0584
.0380
.0201
. 0059
.0003
.0207

11C
3f>
22
8.5
1.5
0
6.6
El
CO
118
82
55
20
. 1.1
64.5

NOx Sk
2.5
4.0
6.5
12.5
22.3
0
                                                                 EPAP
                  129
        530
     Blown Ring (Projected Worst Case)
70.1
Idle
Descent
Approach
Climbout
Takeoff*
Afterburner'''*

.0166
.0162
.0110
.0039 .
.0002
.0102
EPAP
7.2
7.7
2.9
0.8
0
•3.4
30.7
44.8
41.3
36.8
13.8
0.7
31.4
237
2.5
4.0
6.5
12.5
.22.3
0
70.8
                                                                                                                   w
                                                                                                                   i
                                                                                                                  . N)
                                                                                                                   O
      *Data  on  this  row refer to main burner only,

    **0n  during  Takeoff only.  .

-------
Fnjyinc: AT.F502D Thrust (KM) PR
Cert.Confi^.*
Idle
Approach
Climbout
Takeoff
.28.9 11.1
P T M Mr Comb.
(a Lin) (°K) (KB?S) (KB7hr) f/a Ineff.
2.3 397 3.6 168 .0130
5.0 499 8.0 354 .0123
9.8 ' 614 13.1 1005 .0213
11.1 639 14.4 1205 .0232
.0139
.0028
.0002
.0002
EPAP
Dual Orifice Pressure Atomization (Baseline)
Idle
Approach
Climbout
Takoof f
•
.0256
.0042
.0002
.0002
EPAP
Idle-
Approach
Climbout
TakeoEf
• -

M
5.8
HC
5.6
0.6
0.1
0.1
14.8
11.9
1.2
0.1
0.1
31.0

S/V(m" )
3M.O
F.:I:
CO
40.7
11.0
0.5
0.5
112.4
67.6
15.0
0.5
0.5
183.4

rdl.r

NOx Sk
!J'j»<^.«tAi*o'"»
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Ku K.I.I u,'i   Al,r.>02l,
Thrust(KM)


33.4
                                                                     PR
BR
S/V(m  ')
                                                                    13.3
           3H.
Baseline (atm)
Idle
Approach
Climbout
Takeoff
2.1
5.6
11.7
13.3
T
381
511
636
662
M
(Kg?S)
3.76
8.06
15.3
16.82
MF
ICn 7 liir )
173
478
1185
1416
Comb .
f/a Ineff.
.0128
.0165
.0215
.0234
.0240
.0020
.0001
.0001
HC
12.6
0.3
0 •
0
CO
56.0
8.6
0.7
0.7
NOx
TWr^Tgua^raug^rno*1**
2.6
4.7
10.7
12.1
Sk
5
13
25
25
                                                                EPAP
                     28.6
     136.0
Idle at  10.7%
         32.3
Idle
Approach
Climbout
. Takeoff

Idle
Approach
Climbout
Takeoff.
3.18 426 5.29 200 .0105
.0098 3.4 31.8 3.8
EPAP 9.1 92.2 35.4
•

                                                                                                                 w
                                                                                                                 I

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