Environmental Protection Technology Series
HYDRODYNAMICS OF DIVERSIONARY BOOMS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield. Virginia 22161.
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EPA-600/2-78-075
April 1978
HYDRODYNAMICS OF DIVERSIONARY BOOMS
by
William E. McCracken
Mason & Hanger-Silas Mason Co., Inc.
Leonardo, New Jersey 07737
Contract No. 68-03-0490
Project Officers
Frank J. Freestone
John S. Farlow
Oil and Hazardous Materials Spills Branch
Industrial Environmental Research Laboratory
Edison, New Jersey 08817
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory, U.S. Environmental Protection Agency, and approved
for publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products constitute
endorsement or recommendation for use nor does the failure to mention or
test other commercial products indicate that other commercial products
are not available or cannot perform similarly well as those mentioned.
ii
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FOREWORD
When energy and material resources are extracted, processed, converted,
and used, the related pollutional Impacts on our environment and even on
our health often require that new and more efficient pollution control
methods be used. The Industrial Environmental Research Laboratory -
Cincinnati (lERL-Ci) assists in developing and demonstrating new and
improved methodologies that will meet these needs both efficiently and
economically.
This report describes full-scale testing of the flow field around a
commercial oil spill boom. Based on the results presented here, more
efficient operating techniques for booms used in water currents above
0.5 m/s can be developed. The methods, results, and techniques described
are of interest to those interested in specifying, using, or testing
such equipment. Further information may be obtained through the Resource
Extraction and Handling Division, Oil and Hazardous Materials Spills
Branch, Edison, New Jersey.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
iii
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ABSTRACT
The failure of booms to contain floating oil in currents above 0.5
m/s appears to be well established. A method suggested to surmount this
limitation is to use the boom in a diversionary mode to move the oil
into regions of low currents where containment and removal can be accom-
plished. Previous tow tests with booms deployed in a diversionary mode
have shown that oil droplets are often entrained in a flow under the
boom. In these tests, the booms are set at an angle to the direction of
tow and do not extend entirely across the tank. Typically, the length
of boom employed in these tests was 30 m. Failure of the boom to con-
tain oil occurred near the trailing end of the boom over approximately
one-third of the length of the boom.
The U.S. Environmental Protection Agency sponsored a test program
at their oil and hazardous materials simulated environmental test tank
(OHMSETT) to study and document the near-field hydrodynamics of the
trailing end of a diversionary boom. Three-dimensional flow fields were
examined visually, using dye and oil droplets with a towed underwater
video system designed and built as part of the program. Turbulence
intensity was simultaneously documented photographically and measured
with a hot-film anemometer.
This report was submitted in fulfillment of Contract No. 68-03-
0490, Job Order No. 21, by Mason & Hanger-Silas Mason Co., Inc. under
the sponsorship of the U.S. Environmental Protection Agency. This
report covers the period March 1976 through September 1976, and work was
completed as of September 1977.
iv
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CONTENTS
Foreword ill
Abstract iv
Figures vi
Tables vi
Abbreviations and Symbols vii
Acknowledgment viii
1. Introduction and Objectives 1
2. Conclusions 5
3. Recommendations 6
4. Facility and Test Apparatus Description 7
5. Test Procedures and Results 11
6. Discussion of Results 26
References 28
Appendices
A. OHMSETT Description 30
B. Underwater Video 32
C. B.F. Goodrich Sea Boom 34
D. Test Equipment 35
E. Test Procedure for Turbulence Measurement 39
F. Presentation of Test Results 42
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FIGURES
Number Page
1 Experimental set-up 3
2 Sketch of diversionary boom test details 4
3 Video resolution chart 8
4 Video camera and turbulence probe support system . . 12
5 Accumulation and thickening of oil at the
trailing end of the boom 17
6 Oil funneling effects 18
7 Schematic vector diagram of flow patterns at
trailing end of diversionary boom 20
8 Schematic vector diagram of flow patterns of
diversionary boom 21
TABLES
Number Page
1 Video Documentation of Oil Diversion 14
2 Flow Visualization Results 19
3 Turbulence Test Matrix 23
4 Selected Turbulence Intensity Results 25
vi
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ABBREVIATIONS
LIST OF ABBREVIATIONS AND SYMBOLS
cm
cm2/s
dB
dyne /cm
If
ft/min
in
kg
kg/m
kHz
kt
Ibs/ft
In
Ix
m
ynm
m/s
ms"1
m2/s
m3/s
m3s~l
m3
mV
N/m
OHMSETT
ppm
ym
V
—centimeter
—centimeters squared per second
—decibel
—dynes per centimeter
—footcandle
—feet
—feet per minute
—inch
—Kilogram
—kilograms per meter
—kiloHertz
—knot
—pounds per foot
—natural log
—lux
—meter
—millimeter
—rmeters per second
—meters per second
—meters squared per second
—cubic meters per second
—cubic meters per second
—cubic meters
—millivolt
—newtons per meter
—Oil and Hazardous Materials Simulated Environmental
Test Tank
—parts per million
—probe sensor resistance
—micron
—volt
SYMBOLS
E
«•
E0
U
o
On
—voltage
—bridge anemometer output voltage
—bridge anemometer output voltage at zero velocity
—tow speed
—ohms
—degrees (angular)
—degrees (Celsius) - —approximately equal to
vii
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ACKNOWLEDGMENTS
Mr. Frank J. Freestone, the OHMSETT Project Officer, provided
guidance and assistance throughout this project. Mr. J. Stephen Dorrler,
Chief of The U.S. Environmental Protection Agency Oil Spill Technology
Branch, Edison, New Jersey, also offered valuable suggestions.
Dr. Richard Hires from the Davidson Laboratory of Steven's Institute
of Technology provided considerable instrumental and consulting expertise.
Mr. Richard Griffiths of the U.S. Coast Guard kindly reviewed this
report and made a number of excellent suggestions.
The Naval Ship Research and Development Center, Bethesda, Maryland,
loaned their underwater video camera system, which we used in the testing
and refinement of our own.
The author wishes to express his appreciation to Stanley G. Keadle,
Video Technician, and Sol H. Schwartz, Engineering Aide of Mason &
Hanger-Silas Mason Co., Inc., for their individual contributions and
suggestions with the underwater video and turbulence measurement systems
operations developed at OHMSETT as part of this project.
viii
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SECTION 1
INTRODUCTION AND OBJECTIVES
BACKGROUND
Consider that a boom has a particular zone in its design that has
the function of spill control. For a boom operating in the diversionary
mode, the oil spill must reach this control zone and remain there long
enough to be diverted into a collection zone. Water motion relative to
the oil in or near the control zone has two effects: first, to cause
oil droplet formation; and second, to entrain these droplets in water
currents near the boom.
The primary factor that causes interfacial waves and oil entrain-
ment is uncertain. Interfacial waves may be Kelvin-Helmholtz waves caused
by flow instabilities, or they may be induced by background turbulence in
the flow, which then entrains and disperses the droplets. If the turbulence
that leads to droplet formation and subsequent entrainment can be adequately
measured, then the ability to design and build better booms will be
enhanced.
This report presents an experimental study of the flow and the
entrainment of entrained oil around an oil-spill containment boom operating
in the diversionary mode. Previous work has mostly dealt with booms
operating in the containment mode (catenary configuration), and the
importance of such dimensionless numbers as Froude, Weber, Reynolds, and
Strouhal has been clearly noted (4, 8, 9). Droplets have been observed
to form first from the crests of the interfacial waves of the oil slick
(9).
Previous experimental work conducted at the U.S. Environmental
Protection Agency (EPA) oil and hazardous materials simulated environmental
test tank (OHMSETT) facility in Leonardo, New Jersey, has confirmed
field experience that a significant improvement in boom performance
results when a boom is operated at an angle to the current to divert the
oil into quiescent zones for removal. Booms can be operated effectively
in currents greater than 0.5 m/s by decreasing the angle between the
boom and current. However, attempts to calculate or predict the maximum
current in which a boom can be effectively used have been inaccurate
because of the complexities of the problem. Observations of many documented
tests at OHMSETT (6,7) indicate that diversionary boom performance is
affected by the following factors:
Difficulty of maintaining a constant angle between the boom
1
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and current—angular variation along the boom;
Accumulation of oil against the boom and thickening (width
and/or depth) of the oil envelope in the direction of oil
diversion;
Development of interfacial waves and consequent entrainment
along the boom as well as normal to the current.
The purpose of this work was to document clearly the complex three-
dimensional flow patterns near the boom with and without oil and to
measure the intensity of turbulence upstream and downstream of the boom
near the observed failure points along the boom.
The experimental test set-up is shown in Figure 1. A boom was
rigged to be angled 34° to the tow direction using a special tow device
for the trailing end and a tow strut attached to the traveling bridge
for the leading end. In an attempt to maintain a reasonably constant
angle along the boom while under tow, mooring lines were attached as
shown in Figure 2. With this arrangement, three types of experiments
were conducted: 1) simulated oil slick encountering the boom; 2) oil
droplet and dye tracing of hydrodynamic flow patterns; and 3) turbulence
measurements upstream and downstream of the boom. All experiments were
documented with underwater video, above-water video, and 16-mm color
motion pictures (regular and slow-motion) through the underwater windows
along the tank wall.
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Figure 1. Experimental set-up.
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Tank/
Wall
MAIN TOW BRIDGE
Bridge
House
Parachute
Mooring Lines
Oil Slick
Underwater Video
Camera
Turbulence
Probe Strut
Above Water
Video Camera
Tow Cable
Traveling
Tow Device
Trailing
End of Boom
Figure 2. Sketch of diversionary boom test details.
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SECTION 2
CONCLUSIONS
Through the use of newly developed turbulence measurement and
underwater video capabilities, together with flow visualization tech-
niques, certain water flow characteristics have been identified that
directly affect the performance of a diversionary boom. Carefully
documented data have shown that the performance of a boom angled against
a current greater than 0.5 m/s (in which an oil spill is to be diverted
into a collection area), cannot be easily predicted from its performance
head-on against the current (catenary configuration). Streamlined rigid
booms that can be moored to maintain a near constant angle against the
current, with minimal near field turbulence, should demonstrate superior
performance to conventional unstreamlined flexible booms.
Near-field turbulence measurements with a constant temperature,
conical shaped, hot film anemometry probe indicated a marked increase in
turbulence intens'ity from front to back of the boom at tow speeds
between 0.6 and 0.8 m/s. Although localized differences in turbulence
intensity were not measured either in front of or behind the boom, the
underwater video camera did show vertical vortices forming in front of
the boom, spaced approximately 0.30 m apart, when an oil slick was
diverted along the boom at speeds above 0.8 m/s. These vortices effect-
ively entrained the oil and directed it downward into the fast stream
lines, where it was entrained and swept under the boom skirt.
Analysis of all quantitative and qualitative data indicates complex
flow patterns with high turbulence intensity behind the boom and localized
vortices and three-dimensional eddies both upstream and downstream of
the boom. All of these flow characteristics directly affect boom
stability and oil slick stability at the oil/water interface, which in
turn determines the performance limitations of a diversionary boom.
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SECTION 3
RECOMMENDATIONS
Analysis of the hydrodynamic data of booms should continue, both on
a full scale and laboratory level. Developed flow visualization and
turbulence measurement techniques should now be used to compare the
near-field flow patterns of streamlined booms (low turbulence generators)
and conventional booms (high turbulence generators). Quantitative mea-
surements could then be used to correlate flow patterns with perfor-
mance. These would be useful data for improving boom designs.
Turbulence data should be analyzed as completely as possible to
help understand and control the complex flow patterns. Analysis of
frequency spectra would permit a more detailed analysis of the data.
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SECTION 4
FACILITY AND TEST APPARATUS DESCRIPTION
TEST TANK
The OHMSETT facility, located in Leonardo, New Jersey, was built
specifically for testing oil and hazardous materials containment and
recovery equipment (Appendix A). Waves can be generated up to 0.8 m
high and 36.6 m long, and current can be simulated with a towing bridge
up to 3.1 m/s. The tank can be filled with either fresh or sea water.
The sea water of the Raritan Bay (salinity 20 ppt) was used during these
tests.
UNDERWATER VIDEO SYSTEM
To effectively examine the three dimensional flows of water and oil
around a diversionary oil spill control barrier, it was necessary to
develop underwater video systems capable of resolving oil droplets
entrained in the water flows around the spill control devices. The
objective of the test series designed to develop this system was to
define resolution and depth of field. This was to be done in a two
part series: a "target" series using a resolution target, and a "bead"
series using plastic beads as an oil simulant during testing.
Video signals were recorded on an IVC 700, 2.5-cm tape deck and
monitored on two Sony 22.9-cm black and white receivers. The resolution
chart consisted of a 0.9 x 1.2-m sheet of 1.9-cm plywood painted white
(Figure 3). Gloss black vinyl tape and lettering were used to make a
crossing pattern with the tape strips, varying in step from 1.9 to
0.3 cm. The board was suspended from a 10.2-cm rod of polyethylene for
vertical viewing and from two rods on opposite edges for horizontal
viewing.
Two camera systems were used. The Naval Ship Research and Development
Center (NSRDC) provided one camera system that consisted of a vertical
strut of 7.6-cm pipe with a horizontal streamlined tube approximately
0.9-m long that had a ground glass dome and rotatable mirror assembly.
The housing contained a standard resolution camera. The other camera
system, designed and built for EPA, consisted of a torpedo-shaped outer
housing approximately 2.7-m long and was supported by a 6.1-m horizontal
traversing rod held at various depths by a vertical support. Within the
outer housing was an IVC 40 M 805 line, high resolution camera encased
in stainless steel. The camera (which was controlled from the surface)
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00
Figure 3. Video resolution chart.
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looked forward into a flooded mirror compartment in which a rear surface
mirror was set at 45° to look out an opening approximately 25.4 by 30.4
cm. On opposite sides of this opening and facing the target area were
two Hydro LQ1000 underwater lights of 1,000 watts each.
OIL DIVERSION DOCUMENTATION TECHNIQUE
Underwater and above-water video cameras were used to document the
oil slick behavior and droplet formation along the entire length of the
boom (28 m). Both cameras were mounted from a towable truss that could
be longitudinally positioned along the tank (see Figure 2). Both cameras
were also connected to mounts that could be positioned laterally, allowing
complete coverage of the boom. The boom skirt was painted white, with
black numbers sequentially marking off every meter from the trailing
edge to the leading edge. Likewise, white numbers were painted on the
top flange of the boom. Also, a calibrated strip of aluminum was mounted
horizontally from the boom freeboard member and projected outward over
the oil slick along the boom to measure its width as tow speeds were
varied.
FLOW VISUALIZATION TECHNIQUES
The three-dimensional flow patterns near the trailing edge of the
boom were observed and documented with photo/video equipment using a
water soluble dye (Red food dye #40) and several different oils as
tracer elements. Various combinations of oils with specific gravities
above and below 1.0 were used to develop neutrally buoyant tracers.
These tracers were dyed red to enhance photographic/video documentation.
Color, 16-mm motion picture films were taken at normal and slow-motion
speeds for careful analysis of the flow patterns. Tracer fluids were
injected upstream of the boom at various positions along the boom through
three nozzles spaced 10 cm apart vertically. The upper nozzle was
generally positioned within 2.5 cm of the still water surface.
TURBULENCE MEASUREMENT SYSTEM
In addition to the instrumentation listed above, it was decided to
use a single axis, hot film probe for turbulence measurements. The hot
wire or hot film probe is presently the most widely used measuring
system for analysis of the micro-structure of turbulent gas and liquid
flows.
The hot film anemometer possesses features that make it ideal for
testing liquid turbulence:
• Small sensing element dimensions, hence high spatial resolution
and little interference to flow.
• Brief response time as a result of small sensor mass.
• High system sensitivity.
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The use of the single axis probe required an anemometer module, one
linearizer, one power amplifier, a visicorder, two integrating digital
voltmeters, a "tripping box," a counter, and an R.M.S. module. In
addition, a second probe support had to be provided for the single
axis, hot film sensor.
The electronic instrumentation devices for testing were leased from
the Davidson Laboratory of Stevens Institute of Technology. The selected
equipment was as follows:
Probe—DISA 55B87 Conical Film Probe
• Electronic instrumentation—DISA 55D01 constant temperature
anemometer, DISA 44D10 linearizer, DISA 55D35 RMS voltmeter,
and DISA 55D25 auxiliary unit.
A complete photographic record consisting of 35-mm slides, underwater
video films, and 16-mm movies was made of the testing program.
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SECTION 5
TEST PROCEDURES AND RESULTS
GENERAL SET-UP
The procedures for all tests were substantially similar. The boom
was positioned in a diversionary mode and connected by ropes between the
main towing bridge and a light truss, both of which span the tank and
travel its length (Figures 1 and 2). In an attempt to maintain a reasonably
constant 34° angle along the boom while under tow, mooring lines were
attached (Figure 2). With this arrangement, three types of tests were
conducted: 1) oil slick encountering the boom; 2) oil droplet and dye
tracing of hydrodynamic flow patterns; and 3) turbulence measurements
upstream and downstream of the boom. Since the first two tests required
underwater video documentation, an underwater video system was developed
(Appendix B) as well as a tow strut to support it under tow (Figure 4).
OIL DIVERSION TESTS
The maximum current in which a boom can operate when angled to the
current without oil loss can be estimated from its performance in the
containment (catenary) mode. Knowing that oil loss in the containment
mode occurs when the. current normal to the boom exceeds 0.4 m/s (typical
for many oils), it can be conjectured that oil loss with a boom angled
to the current will occur when the component of that' current normal to
the boom exceeds 0.4 m/s. So for the test boom angled at 34° to the
current and capable of containing oil in 0.4 m/s current, a projected
maximum current in which it should divert oil without entrainment loss
is 0.7 m/s. However, during an earlier test project including this boom
(5), OHMSETT diversionary performance data indicated oil loss at 0.6
m/s. Oil entrainment was generally observed to occur along the trailing
one-third of the boom.
Utilizing previous test data and results, it was hypothesized that
there were three causes (assuming test tank effects were negligible) for
this inability to attain maximum projected performance:
1) Inability to maintain an angle of - 34° against the current,
especially at the trailing end;
2) An accumulation of spill material being diverted all along the
boom toward the trailing end, resulting in oil thickening at
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Figure 4. Video camera and turbulence probe support system.
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the trailing edge and drainage losses; and
3) Complex turbulent flow patterns caused by three dimensional
flow near-field of the trailing end as opposed to the predom-
inately two dimensional flow near-field of the catenary boom
apex.
To test these hypotheses, a B.F. Goodrich boom (Appendix C) was
rigged and tested with oil. The test set-up was aimed toward accurate
and high resolution video documentation from above and below a diversionary
boom in full-scale operation under controlled test conditions. Tests
were run at tow speeds of 0.6, 0.7, and 0.8 m/s in an oil slick 9 m
wide, 1 mm thick and uniformly laid down at the rate of 0.4 m3/min for
3.5 min. For ambient temperatures near 25°C, the oil properties were:
viscosity = 1.5 x lO"1* m2/s
• interfacial tension = 15 x 10~3 N/m
surface tension = 30 x 10"3 N/m
• specific gravity = 0.87
percent water = 0.2%
A test run consisted of positioning the cameras at approximately
right angles to each other and viewing the horizontal plane above the
boom and the underwater vertical plane along the oil side of the boom
skirt. With the boom tensioned between the main tow bridge and a port-
able tow device at the trailing end, the tow speed was quickly brought
to 0.6 m/s, the oil slick lay-down was begun, and video documentation
began. As oil accumulated against the boom and built up a steady diversion
rate at the trailing end, conditions were held constant for at least
15 s to accommodate full photographic coverage. Then the tow speed was
increased to 0.7 m/s and 0.8 m/s in similar fashion. Duration of each
test run was about 3.5 min, after which the tow systems were moved back
to the starting position.
The results of this test series are tabulated in Table 1 and sup-
port the three hypotheses. Oil droplet formation was observed as far as
18 m from the trailing end of the boom, where the boom angle was between
25° and 30° at a tow speed of 0.8 m/s. Using 28° as an approximation of
the boom angle, the component of tow speed (relative water motion)
normal to boom is 0.38 m/s. This figure is 12% lower than the 0.43 m/s
critical velocity speed for slick failure previously documented using
this boom operating in the catenary configuration (5). The difference
may be due to using different oils in these two tests.
Droplet size increased from about 3 mm at the 16-m mark to 25 mm at
the 3-m mark with the tow speed set at 0.8 m/s. Droplet size was
associated with the accumulation and thickening of the oil slick to a
maximum of about 0.15 m at the trailing end of the boom as shown in
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TABLE 1. VIDEO DOCUMENTATION OF OIL DIVERSION
Distance from
trailing edge
of boom, m
0-3
Tow speed,
m/s (kts)
0.6 (1.2)
0.7 (1.4)
Boom angle, Oil entrainment description
in degrees underwater video
Small amounts, small
droplets
: Significant amounts,
Oil stream width
along boom, above
video, m
0.75 at trailing
edge, 0.50 at 3 m
0.63 at trailing
3-7
7-10
0.8 (1.6)
0.6 (1.2)
0.7 (1.4)
0.8 (1.6)
0.6 (1.2)
0.7 (1.4)
0.8 (1.6)
60
50
40
larger droplets of about
6 mm diameter
Large amounts of oil ripping
off, 18-25 mm droplets at
trailing edge
No droplets
Droplets begin to form,
approx. 3-6 mm diameter
High rate of droplet
formation, larger size,
18 mm diameter
Nq droplet
Droplets begin to form
High rate of droplet
formation
edge, 0.40 at 3 m
0.50 at trailing
edge, 0.30 at 3 m
0.80 at 6 m mark
0.75 at 6 m mark
0.60 at 6 m mark
0.43 at 9 m mark
0.50 at 9 m mark
0.41 at 9 m mark
(Continued)
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TABLE 1. (Continued)
Distance from
trailing edge
of boom, m
Tow speed,
m/s (kts)
Boom angle,
in degrees
Oil entrainment description
underwater video
Oil stream width
along boom, above
video, m
10-13
13-16
16-24
25-28
0.6 (1.2)
0.7 (1.4)
0.8 (1.6)
0.6 (1.2)
0.7 (1.4)
0.8 (1.6)
0.6 (1.2)
0.7 (1.4)
0.8 (1.6)
0.6 (1.2)
0.7 (1.4)
0.8 (1.6)
35
30
25
15
No droplets
Very few droplets
Nominal rate of droplet
formation
No droplets
Slight droplet formation
Nominal rate of droplet
formation (3 mm diameter)
No droplets
No droplets
A few detectable droplets
to 18 m mark
No droplets
No droplets
No droplets
0.43 at 12 m mark
0.38 at 12 m mark
0.38 at 12 m mark
0.25 at 15 m mark
0.17 at 15 m mark
0.12 at 15 m mark
0.17 at 21 m mark
0.12 at 21 m mark
0.12 at 21 m mark
0.12 at 25 m mark
0.08 at 25 m mark
Cannot measure
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(Figure 5). Droplets also follow along the underside of the diverting
slick and grow by colliding with and contacting other droplets. The
failure of oil under the boom at the trailing end and at 0.8 m/s can be
described better as drainage than as entrainment. When tow speeds were
increased beyond 0.8 m/s, vortices were observed that show oil funneling
effects (Figure 6).
The data in Table 1, also show that as the tow speed was increased
from 0.6 to 0.8 m/s, the oil slick was compressed against the boom as
the "stream width" changed markedly from the 10-m mark to the trailing
end of the boom. Here the boom angle was the greatest (40° -»- 60°) . Of
course, since oil is incompressible, both the oil stream depth and speed
increased with distance from the upstream end of the boom, and both
effectively contributed to oil loss under the boom.
FLOW VISUALIZATION TESTS
With the same general test set-up described above, several different
tracer elements were tested to observe the three dimensional flow patterns
near the trailing edge of the boom. Up to two tracer element injectors
(described in Section 4), were used to inject tracer fluids between 2.5
and 30.0 cm beneath the water surface at tow speeds of 0.50 to 1.0 m/s.
During each test run, the traced flow patterns were documented with the
underwater video camera, and for selected runs, with a color 16-mm movie
camera. Table 2 summarizes the test runs, and typical traces are schema-
tically shown in Figures 7 and 8. Also, the flow visualization records
were summarized in an OHMSETT-edited, unnarrated, 16-mm movie (color
film and multiplexed black and white video film).
TURBULENCE MEASUREMENTS
Basically, two mechanisms exist for oil loss under a boom skirt in
calm water: entrainment and drainage. For booms operating in the
diversionary mode, these mechanisms have been observed to occur at about
0.65 m/s, depending on the angle between the boom and current. Drainage
has been observed at the trailing edge of the boom, with entrainment at
various points along the length of the boom.
Some investigators feel that entrainment is due primarily to
interfacial turbulence. Instabilities form at the oil/water interface;
turbulent oil waves form and droplets develop that either become en-
trained in the water flow under the boom or move about near the inter-
face. Since turbulence is such an integral part of boom performance,
turbulence intensity measurements were taken at various positions upstream
and downstream of the boom in the near-field regions of observed failure
points.
Point measurement of turbulence along the oil/water interface was
not feasible with existing technology. Hot film anemometry probes,
presently used for point measurements, were subject to contamination by
the oil droplets that encounter the sensor element. Using the DISA
55B87 conical film probe, gross measurements of turbulence intensities
16
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Figure 5. Accumulation and thickening of oil at the trailing end of the boom.
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oo
Figure 6. Oil funneling effects,
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TABLE 2. FLOW VISUALIZATION RESULTS
Test Position of Tow
no. nozzles, m* speed,
x y z m/s
Tracer Fluids
Type 1 SG* Type 2 SG Type 3
Combination
ratios
1 2
Comments
1 1.8 0.60 0.30
2 1.8 0.45 0.08
3 1.8 0.30 0.08
4 1.8 0.30 0.00
5 1.8 0.30 0.00
6 1.8 0.15 0.00
7 1.8 0.15 0.00
8 1.8 0.15 0.00
0.50 M-100** 1.00 1
0.75 M-100 1.00 1
1.00 M-100 1.00 1
0.50 DOP*** 0.98 1
0.75 Dye 1
0.50 M-120**** 1.20 Octanol 0.83 Red dye 1/2 1/2
0.75 DOP 0.98 Diesel 0.85 Red dye 2/3 1/3
0.75 M-120 1.20 Octanol 0.83 Red dye 1/2 1/2
*Use the axes key given with Table 4.
**Meriam 100 gage oil
***Dioctyl phthalate
****Meriam 120 gage oil
Good trace
Good trace
Good trace
No droplets,
too viscous
Poor trace
Good trace
Good trace
Good trace
-------
to
O
Region of
Hydraulic Jump
— 1
. Tank
Bottom
T
— 2
0
Figure 7. Schematic vector diagram of flow patterns at trailing end of diversionary boom (section
view). All measurements in meters.
-------
9.1
6.1 _
3.0 _
0 ->
3.0
Limit of
Data
J / >>
-*-?
6.0 4.5 3.0 1.5 0 .3 .6 .9 1.2
2.4
Figure 8. Schematic vector diagram of flow patterns of diversionary boom (Plan View). All
measurements in meters.
-------
were obtained without the oil slick, in salt water that was highly
filtered to 30 m visibility and less than 1 ppm hydrocarbons.
Test procedures required that the boom be positioned in a diversionary
mode and connected by ropes between the main towing bridge and a towable
truss. With the probe positioned in a quiescent zone, the probe tempera-
ture compensation (over-heat ratio) was set. Calibration runs were then
made at various tow speeds (0.25 -»• 1.0 m/s) over a 60-m section of the
tank. Tow speeds were accurately determined with a photocell system
connected to a digital timer. Logarithmic plots of the anemometer volt-
age outputs at various tow speeds were used to establish linearizer
characteristics. After the linearizer voltage output was calibrated
against tow speed, the probe was positioned near the boom for data
measurements using this same procedure, and the test matrix in Table 3
was executed. During the entire testing procedure, observations were
made on video tape, 16-mm movies, and 35-mm slides.
Linearizer output was monitored for the mean velocity component and
the turbulence. Local turbulence intensity (%) was directly obtained as
the r.m.s. voltage of the fluctuating velocity component divided by the
local mean velocity voltage from the linearizer. Typical data are
presented in Table 4. Since the boom changed configuration with tow
speed, the closest turbulence measurements obtainable were 0.5 m from
the boom.
The probe was then oriented parallel to the boom to monitor the
turbulence associated with water flow along the boom (Test Number 6).
No significant change in turbulence intensity was measured.
Calibration checks were taken periodically to correct for probe
contamination effects and ambient temperature changes during data col-
lection periods.
Other measurements included air (wind speed, direction, temperature)
water (temperature at the tank surface), and time (duration of test
run). In addition, measurements were taken from the electronic instrumen-
tation systems as outlined in Appendix D.
22
-------
TABLE 3. TURBULENCE TEST MATRIX
Tow speed, m/s
0.25
0.25
0.38
0.38
0.51
0.51
0.76
0.76
0.89
0.89
1.02
1.02
0.25
0.25
0.38
0.38
0.51
0.51
0.76
0.76
0.89
0.89
1.02
1.02
0.25
0.25
0.38
0.38
0.51
0.51
0.76
0.76
0.89
0.89
1.02
1.02
0.25
0.25
0.38
0.38
0.51
0.51
Probe
Behind
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
position
Front
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Distance (x)
boom to strut, m
0.305
0.305
0.610
0.610
0.915
0.915
1.22
1.22
1.52
1.52
1.83
1.83
0.305
0.305
0.610
0.610
0.915
0.915
1.22
1.22
1.52
1.52
1.83
1.83
0.305
0.305
0.610
0.610
0.915
0.915
1.22
1.22
1.52
1.52
1.83
1.83
0.305
0.305
0.610
0.610
0.915
0.915
Probe depth
(z) , m
0.101
0.101
0.101
0.101
0.101
0.101
0.101
0.101
0.101
0.101
0.101
0.101
0.304
0.304
0.304
0.304
0.304
0.304
0.304
0.304
0.304
0.304
0.304
0.304
0.660
0.660
0.660
0.660
0.660
0.660
0.660
0.660
0.660
0.660
0.660
0.660
0.406
0.406
0.406
0.406
0.406
0.406
(Continued)
23
-------
TABLE 3. (Continued)
Tow speed, m/s
0.76
0.76
0.89
0.89
1.02
1.02
Probe position Distance (x)
Behind Front boom to strut, m
x 1.22
x 1.22
x 1.52
x 1.52
x 1.83
x 1.83
Probe depth
(z), m
0.406
0.406
0.406
0.406
0.406
0.406
24
-------
TABLE 4. SELECTED TURBULENCE INTENSITY RESULTS
Turbulence
Test
no.
1
2
3
4
5
6
7
8
9
10
11
Tow speed
intensity
m/s (kts) %
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
1.
72 (1.4)
62 (1.2)
72 (1.4)
72 (1.4)
72 (1.4)
72 (1.4)
25 (0.5)
56 (1.1)
82 (1.6)
83 (1.6)
08 (2.1)
2.
3.
2.
2.
2.
3.
13.
14.
30.
23.
30.
8
5
4
8
3
4
0
7
0
6
0
Probe
X
2.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
50
50
50
50
67
67
91
91
45
60
45
position, m*
y
0.3
7.0
7.0
7.0
17.0
16.0
1.0
0.9
0.6
0.6
0.3
Probe orientation
relative to
boom
z tow direction
0.10
0.18
0.10
0.10
0.10
0.10
0.66
0.66
0.66
0.66
0.66
Fore,
Fore,
Fore,
Fore,
Fore,
Fore, J_
Aft,
Aft,
Aft,
Aft,
Aft,
*Axes
Key:
/
^ —
€
'
L^
^>7
Water
Surface
25
-------
SECTION 6
DISCUSSION OF RESULTS
GENERAL DISCUSSION
Utilizing the newly developed turbulence measurement and underwater
video capabilities together with flow visualization techniques, certain
water flow characteristics have been identified that directly affect the
performance of a diversionary boom. Carefully documented data have
shown that the performance of a boom angled against a current greater
than 0.5 m/s in which an oil spill is to be diverted into a collection
area cannot be easily predicted from its performance head-on against the
current (catenary). Consideration must be given as to how a conventional
boom can be moored with numerous tie lines to maintain a nearly constant
angle against the current. This should reduce the near-field turbulence
and associated vortex streets that draw oil down and under the boom.
Unidirectional turbulence measurements are possible with a constant-
temperature, conical, hot-film probe (DISA) at OHMSETT if the errors
caused by the other two flow components are negligible and if several
times each day, care is taken to check the linearizer characteristics
and calibration factor for converting output voltage to velocity.
Electronic and thermal noise can cause problems that require sharp
filtering capabilities for their resolution. Also, to resolve the
three-dimensional components of turbulence, a triple axis probe is
required, which triples the complexities and difficulties of accurate
measurements. Acquiring and maintaining a constant calibration with
linear response over the entire range of velocities and frequencies is
the main problem in using this sensitive instrumentation. Triple axis
work is not likely to be feasible in an outdoor tank such as OHMSETT
(5).
Development of a remotely controllable underwater video system at
OHMSETT greatly enhances testing oil spill control equipment, as was
demonstrated here. Future improvements to the system include the installa-
tion of traveling rail systems for the video truss and the video tow
strut to allow complete coverage between the main and auxiliary bridges.
Previous tests (none of this type were conducted here) have shown a
tremendous variation in boom performance with oil properties, especially
specific gravity (7). This property was not varied during the test
project.
EPA has sponsored several fast current boom development projects in
26
-------
the past that have demonstrated to some extent the ability to design
booms for hydrodynamic smoothness and associated turbulence reduction
(2, 3). We hope that this work will assist future boom development
projects aimed at improving oil spill control capabilities for a cleaner
environment.
TEST TANK EFFECTS ON DATA
Test tanks can only approximate actual waterways. There is no real
current, except with flumes. A separate report would be needed to
rigorously define all of the differences, but the primary one that
affected this test project was that the currents are simulated by the
relative motion of the traveling bridge with respect to "motionless
water." In effect, the velocity profiles horizontally across the tank
(wall to wall) and vertically from the water surface to the tank bottom
are flat and that the background turbulence is zero except for distur-
bances due to convection, the wind, or the previous test run. As a result,
the background turbulent intensity is not a fixed value but varies in-
versely with tow speed. However, typical river velocity profiles are
generally considered to be parabolic from shore to shore and approximately
linear from bottom (where current is zero) to water surface (maximum
current). For some rivers with very steep banks, the surface velocity
profile becomes nearly flat. But for most cases, when the diversionary
technique is being applied, the very reason for setting the boom at a
smaller angle with the mid-stream current is to prevent those currents
greater than 0.5 m/s from directly encountering the boom and causing oil
loss. Ideally, the fast mid-stream currents are used to divert oil to
the much slower current zone near the shoreline. When testing this
concept in the test tank, obviously there was no "slow current" zone.
The bridge moves with respect to the tank water, and this relative
velocity is the same all across the tank.
How does this affect the correlation of diversionary boom performance
in the test tank and the real world? Boom failure inadvertently occurred
at the trailing end which was angled the most against the current and
should have been in the "quiet zone" (that does not exist in a test
tank). If a "quiet zone" did exist near the test tank wall (or trailing
edge of the boom), the "no oil loss" test speed would have increased and
been in closer agreement with actual performance in waterways with
parabolic surface velocity profiles and "quiet zones." The result is
that the diversionary "no oil loss" tow speeds are low and conservative.
However, as shown by the results of this work, other difficulties and
water flow complexities contribute to the performance level too.
27
-------
REFERENCES
1. Bradshaw, P.:1971, An Introduction to Turbulence and Its Measurement,
Pergamon Press, New York.
2. Dorrler, J.S., Ayers, R., and Wooten, D.C.:1975, High current
control of floating oil. In: Proceedings of Joint Conference on
Prevention and Control of Oil Spills. Washington, D.C.: American
Petroleum Institute.
3. Folsom, B.A. :1975, Development of a streamlined oil retention boom.
Unpublished interim report for the U.S. Environmental Protection
Agency, Office of Research and Development, Cincinnati, 0. Ultra-
systems Contract No. 68-03-0403, December 1975.
4. Freestone, F.J., McCracken, W.E., and Lafornara, J.P.:1976, Performance
testing of spill control devices on floatable hazardous materials.
In: Proceedings of National Conference on Control of Hazardous
Material Spill. Information Transfer, Inc., Rockville, Maryland.
5. Hale, L.A., Norton, D.J., and Rodenberger, C.A. :1974, The Effects of
Currents and Waves on an Oil Slick Retained by a Barrier. U.S.
Coast Guard, Office of Research and Development, Washington, D.C.
Report No. CG-D-53-75.
6. Hires, R.I.:1976, Some Comments on the Use of Hot Film Anemometry
at EPA OHMSETT Facility. Stevens Institute of Technology, Davidson
Laboratory: Technical Note 878.
7. McCracken, W.E.:1977, Performance Testing of Selected Inland Oil
Spill Control Equipment. U.S. Environmental Protection Agency,
Office of Research and Development, Cincinnati, 0. Report No. EPA-
600/2-77-150, August 1977-
8. Warschauer, K.A., Vijge, J.B.A., and Boschloo, G.A.:1974, Some
experiences and considerations on measuring turbulence in water
with hot films. Applied Scientific Research; 29. April 1974.
9. Wicks, M.:1969, Fluid dynamics of floating oil containment by
mechanical barriers in the presence of water currents. Proceedings
of Joint Conference on Prevention and Control of Oil Spills,
Washington, D.C.: American Petroleum Institute.
28
-------
10. Wilkinson, D.L.:1972, Dynamics of contained oil slicks. In: Proceedings
of the American Society of Civil Engineers, Journal of the Hydraulics
Division. June 1972, pp. 1013-1030.
29
-------
APPENDICES
APPENDIX A. OHMSETT DESCRIPTION
Figure A-l. OHMSETT.
The EPA OHMSETT facility provides an environmentally safe place to
conduct testing and development of devices and techniques for the control
of oil and hazardous materials spills.
The primary feature of the facility is a pile-supported, concrete
tank with a water surface 203.3 m long by 19.8 m wide and with a depth
of 2.44 m. The tank can be filled with either fresh or salt water. The
tank is spanned by a towing bridge with a capability of towing loads up
to 15422.4 kg at speeds to 3.05 m/s for a duration of 45 s. Slower
speeds yield longer test runs. The towing bridge is equipped to lay oil
on the surface of the water several feet ahead of the device being
tested, such that reproducible thicknesses and widths of oil slicks can
be achieved with minimum interference by wind.
The principle systems of the tank include a wave generator and
beach, a bubbler system, and a filter system. The wave generator and
absorber beach have capabilities of producing minimum reflection waves
up to 0.8 m high and 36.6 m long, as well as a series of reflecting,
complex waves meant to simulate the water surface of a harbor or estuary.
The water is clarified by recirculation through a 1.26 m3/s, diatomaceous
earth filter system to permit underwater photography and video imagery
30
-------
and to remove the hydrocarbons that enter the tank water as a result of
testing. Oil is controlled on the surface of the water by a bubbler
system that prevents oil from reaching the tank walls, the beach, or the
wave generator. This system is designed to speed the clean up between
test runs, since a clean tank surface is essential to reproducible oil
spill conditions. The towing bridge has a built-in skimming board that,
in conjunction with the bubbler system, can move oil on to the north end
of the tank for cleanup and recycling.
When the tank must be emptied for maintenance purposes, the entire
water volume (9842 m3) is filtered and treated until it meets all applicable
State and Federal water quality standards before being discharged.
Additional specialized equipment will be used whenever hazardous materials
are used for tests. One such device is a trailer-mounted carbon treatment
unit that is available for removal of organic materials from the water.
Tests at the facility are supported from a 650-m2 building adjacent
to the tank. This building houses offices, a quality control laboratory
(which is very important since test oils and tank water are both recycled),
a small machine shop, and an equipment preparation area.
This government-owned, contractor-operated facility is available
for testing purposes on a cost-reimbursable basis. The operating contractor,
Mason & Hanger-Silas Mason Co., Inc., provides a staff of 11 multi-
disciplinary personnel. EPA provides expertise in the area of spill
control technology, and over all project direction.
For additional information, contact:
OHMSETT Project Officer
U.S. Environmental Protection Agency
Office of Research and Development
Edison, New Jersey 08817
Phone: 201-321-6631
31
-------
APPENDIX B. UNDERWATER VIDEO
To examine effectively the three-dimensional flows of water and oil
around the diversionary boom, it was necessary to select an underwater
video system capable of resolving the entrained oil droplets. This was
done in a two-part test series: a target series using a resolution
target (Figure 3) and a bead series using plastic beads as an oil sim-
ulant. Two camera systems were used for comparison— one system borrowed
from the Navy Ship Research and Development Center (the NSRDC fish) in
Bethesda, Maryland; and the other (the EPA fish), an IVC-40 M 850 line,
high resolution camera with a standard visible light band vidicon and
remotely controlled focus, iris, and zoom.
The tests were conducted to determine the following capabilities:
1) Resolution with and without underwater lights.
2) Differences in performance of a faired camera housing (NSRDC
camera) and an unfaired cylindrical camera housing (EPA) under
tow up to 3.0 m/s.
3) Wide field of vision using either a rotatable mirror aligned
with the camera (NSRDC) or externally rotating and tilting the
camera and canister.
The EPA fish and NSRDC fish were mounted near each other and
positioned so that each would have approximately the same lighting
depth, water conditions, and viewing angle. Visibility in this case was
defined as the distance an object could be sharply seen by the human eye
through the test tank window. Ambient light readings were taken in foot
candles, 1.8 m above the camera with a Spectra Pro meter using an
incident dome. Resolution was defined as follows: 1) Good: sharp,
clean lines; 2) Fair: slight blur, but distinguishable lines; 3) Poor:
very blurred, undistinguishable lines.
During the course of resolution testing, observations were made of
related conditions. In relation to viewing angles, zoom, pan, and tilt
were found to be essential to find and view the object properly. Even
a slight target movement because of waves or tow forces meant loss of
image or major time delays if the field of view was not changed.
Although the zoom, pan, and tilt motions were very useful, the movements
appeared to be sluggish.
Three different types of distortion were discerned. Distortion
resulting from camera and target motion was noticeable at 0.51 m/s as a
small shadow movement, but it did not distract from the picture image
significantly. Distortions resulting from the pan and tilt assembly
were of two types: (a) primary distortion, caused where the field of
vision became larger than the rotatable mirror,, was a shaded area or
double image; and (b) secondary distortion, a result of viewing objects
at sharp angles, was elongated images.
32
-------
The interaction of the controls (zoom, focus, and iris) at low
light conditions required excessive amounts of time for focusing. The
smaller the iris, the easier the image was to focus. Reducing the iris
size was accomplished by increasing the light entering the camera or by
increasing the camera's sensitivity electronically.
The procedure followed in the testing program began by positioning
both cameras and the resolution chart. After checking out the electronics,
ambient conditions were recorded; these included wind speed and direc-
tion, air and water temperature, water surface condition, cloud cover,
and tank water visibility. Test conditions such as waves, lighting, or
tow speed were established before recording resolution, depth of field,
and other general observations.
Before testing began, a section of the tank bottom was vacuumed to
remove dark layers of sediment and expose the white paint below. Light
meter readings taken 5.1 cm above the surface of the water in a reflective
mode indicated that the foot candle readings increased from 2368.1 lux
(Ix) over the dirty bottom to 10763.9 Ix over the clean bottom. Although
the cleaned area was narrow (1.8 m), a significant increase in picture
quality was noticed when the camera passed through this area.
Each camera's viewing area was somewhat limited in maneuverability.
The NSRDC camera could be rotated and tilted, but not zoomed. The EPA
fish could be zoomed, but its viewing angle could not be varied. To
standardize the test, the NSRDC camera was positioned at approximately
the same angle as the EPA fish, which was then zoomed to approximately
the same magnitude as the NSRDC camera. Since the NSRDC camera had no
lights of its own, the EPA lights were used to illuminate its target;
but it should be noted that there was an additional 0.6 m for the EPA
light to travel to the NSRDC target. The entire camera and mirror
assembly was controlled above water. For detailed descriptions of the
equipment used in the testing program, refer to Appendix D.
As a result of these tests and studies, the underwater video system
was designed with the following characteristics:
1) The IVC 40 M camera was determined to have adequate resolution
capabilities (0.3-cm beads at 6.0 m) with ambient light (-
2152.8 Ix), highly filtered water, and a clean, white tank
bottom.
2) An external pan and tilt unit with remote control was attached
to the cylindrical canister at the end of a faired tow strut.
The video camera tow strut is shown in Figure 4, mounted to the
auxiliary bridge.
33
-------
APPENDIX C. B.F. GOODRICH SEA BOOM
Design Characteristics
1. Draft—0.30 m
2. Freeboard—0.15
3. Flotation—continuous chambers of closed-cell foam, protected
by 0.635-cm PVC coating and secured at the boom ends with
wooden plugs.
4. Ballast—tubular extrusions filled with lead shot and sand.
5. Skirt material—0.635-cm-thick vinyl sheet reinforced with
rib handles of urethane.
6. Tension member—self-tensioning boom.
7. Weight—11.92 kg/m
8. Excess buoyancy—10.42 kg/m
9. Standard length—7.16 m
Tow Point Connection
1. A bridle arrangement was connected to the manufacturers-
provided SEALOC system. This consists of a piano hinge
arrangement with fiberglass pins.
Comments
1. Required 10 men/section for handling (as well as crane for
deployment and removal).
2. End plates and connections were easy.
34
-------
APPENDIX D. TEST EQUIPMENT
The following section of this report describes the electronic in-
strumentation used for hot film turbulence measurements. Figure D-l
depicts each instrument and its position in the instrumentation set-up.
Individual systems are detailed in the following manner:
Manufacturer: Name of system
Description of equipment
Technical Data
Certain materials are reprinted courtesy of the individual manufacturers.
PISA Conical Hot Film Probe
The probe used during the testing was a conically shaped probe with
a thin nickel film placed around the tip of the cone. The sensor was
thinly coated with quartz to protect the metal film against ambient
influences; sensors for use in electrical conducting liquids are coated
to a thickness of approximately 2ym to be secured against breakthrough
and against electrolysis of the nickel film.
The particular advantage of the conical configuration of this probe
is its insensitivity to mechanical contamination, since dirt particles
will not readily stick to it because of its pointed shape.
Technical data:
Sensor dimensions: 1.4 mm x 0.1 mm
Sensor resistance: 15fi
Maximum sensor temperature: 150°C
Maximum ambient temperature: 100°C
Minimum velocity: 0.01 m/s
Maximum velocity: 25 m/s
Frequency limit: (FCMAX): 30 kHz
PISA Electronics 55D01 Anemometer
The constant-temperature anemometer measurements are based on
balancing the convective heat loss as a result of the mass flow around
the hot film probe.
The unit consists of a Wheatstone bridge and an amplifier. Speci-
fications are available from DISA Electronics, Franklin Lakes, New
Jersey.
DISA Electronics 55D10 Linearizer
The linearizer performs the function of canceling the anemometer
output voltage corresponding to no-flow probe output and raising the
output voltage by a suitable exponent. The linearizer transfer function
results in a voltage that varies directly as the flow velocity so that
35
-------
grd
•
.
AnemomG
L61_
J^
Linearizer
i
_t
wire Probe
cable
Mean Velocity
(Linearized
Voltage)
Turbulence
Intensity
(RMS
voltage)
Figure D-l. Instrumentation diagram for single-axis probe.
36
-------
the calibration curve starts at the origin of the system of co-ordinates,
reaching approximately 10 volts for the highest velocity occurring in
practice. A feature of the linearizer is that it uses logarithmic
amplifiers to provide optimum linearization throughout the range. In
this way, continuous linearization of the anemometer output voltage is
obtained. In other words, the same order of linearization accuracy is
obtained for any voltage within the range in question.
Technical data:
Accuracy: Linearization on the order of 0.5% to 3% can be accomplished,
depending on conditions of measurement
Output voltage range: 0 to 10 volts
Frequency range: 0 to 100 kHZ at output voltage 5 volts and exponent
m = 2.0
Output impedance: 180 fi
Power supply: 100/220 volts ±10%, 50 to 60 Hz
Input impedance: 6.8 kfl to 28 kfl, continuously adjustable
PISA Electronics 55D25 Auxiliary Unit
This auxiliary unit converts the output signal of the anemometer or
linearizer into a form suitable for further processing by other instruments.
For this purpose, it incorporates an amplifier, switchable filters,
and a square-wave generator for making the anemometer square-wave test.
Technical data:
Gam: calibrated 1, continuously variable from 1 to approximately 3.
Frequency range: D.C. to 500 kHz
Input impedance: Approximately 16 kfl
Output impedance: Approximately 160 fl
High pass filter: 11 positions DC 1-1000 Hz
Low pass filter: 11 positions 0.2-200 kHz
PISA Electronics 55D35 RMS Voltmeter
The voltmeter measures the true root means squared (RMS) values of
AC voltages in the wide range from 300yV to 300 volts. When used with
an anemometer, its chief application is the determination of the dynamic
components of flows.
Readout was provided by an accuracy meter. External indication was
also possible via a BNC socket. The RMS voltmeter had an additional
output socket at which the squared RMS value of the AC voltage under
measurement was available. This output was used for determining the
turbulence energy spectra of flows.
Technical data:
Full-scale ranges: 1 mV to 300 Volts
Accuracy of RMS output at mid-range frequencies: ±1% of maximum
37
-------
output voltage, down to -30dB.
Accuracy of squared RMS output at mid-range frequencies: ±1% of
maximum output voltage, down to -30dB.
38
-------
APPENDIX E. TEST PROCEDURE FOR TURBULENCE MEASUREMENT
Manpower Allocations
The following allocations of duties were made:
1. Test director—responsible for running the tests according to
the prescribed test matrix and test procedure; manages the
test personnel.
2. Control room operator—operates the traveling bridge from the
control tower at the north end of the tank. He also collects
the data for ambient conditions.
3. Photographer—photographically documents the test runs with 35
mm color slides, 16-mm color motion pictures, and the under-
water video system.
4. Data documentation technician—records test data and follows
directions of test director.
Pre-test Checklist
To ensure that all test systems and equipment were maintained and
ready for the test day, the following checklist was used before the first
test run:
1. Bridge drive system operating.
2. Test device operational.
3. Test instrumentation operational.
4. Test support equipment operational.
5. Photographic systems ready.
6. Test personnel prepared and ready.
7. All pre-run data and checklists completed.
Test Sequence
The following test sequence was used for the hot-film probe turbulence
tests:
1. Position the traveling bridge and test devices for testing.
2. Position all personnel for testing.
3. Inform all test personnel of test conditions taken from the
test matrix.
39
-------
4. Set probe controls and energize probe by switching to operational
mode from standby mode.
5. Give three blasts on the air horn to clear the tank and alert
all test personnel of test run.
6. Using either an intercom system or walkie-talkies, begin a
countdown from five with the control room operator to begin
bridge motion at zero and one blast on the air horn.
7- Initiate the bridge movement and photographic documentation
with one blast on the air horn.
8. Record test data during test run (data documentation technician).
9. Begin countdown from five to stop the bridge (test director).
10. Return bridge and boom to starting point and prepare for the
next test.
Data Analysis
The test director performed all data analysis and reduction. All
data sheets were submitted to him for compilation onto master raw data
sheets as shown in Appendix F. The ultimate responsibility for proper
data collection, analysis, and presentation belongs to the OHMSETT
project engineer, who writes the final report for the EPA project officer.
Conical-Type Hot Film Probe Procedures
1. The probe was turned on and sufficient warm-up time allowed.
2. Controls were set as follows:
A. Meter switch to 10.
B. Decade resistance to 00.00.
C. Loop control at standby.
D. Bridge ratio at 1:20.
E. Gain adjustment at 3.
F. Temperature—resistance switch at neutral.
3. The probe support and shorting probe were attached by a 5-
m probe scale.
4. The shorting probe was replaced with an actual probe. The
decade resistance was set to a value that gave no meter deflection
when the temperature resistance switch was set.
5. Resistance was noted on the decade box, and this value was
multiplied by 1.1 (operating resistance for correct operation
was determined by the overheat factor, which could not exceed
1.1 times the ambient resistance of the probe).
40
-------
Probe sensor resistance = RTemp
Leads resistance = ^.9
(RTemp - ^.9) 1.1 + R0.9 = Operation resistance
6. Appropriate operating resistance was set.
7- The probe was energized by switching to operation mode from
standby mode.
8. Voltage outlet from the probe was observed and noted.
9. Readings at zero speed of the output voltage E were taken from
the anemometer.
10. Eg (Bridge anemometer output voltage) was integrated over 60.9
m for the following tow speeds (u):
0.25 m/s 0.76 m/s
0.38 0.89
0.51 1.02
0.64 Repeat stationary
11. The following formula was used to calculate the exponent which
was plotted as stated (see p. vii for definitions of abbreviations
and symbols).
In [(EB/E0)2-!] vs In u
12. The fictive zero was set if necessary to ensure an adequate
linear relationship.
In [(E]j/.9Eo)2-l] vs In u on linearizer.
13. The exponent determined from the previous plot was set.
14. Temperature compensation was set.
15. With the probe at zero speed and the fictive voltage output
from the anemometer, the zero adjust was set to zero output
from the linearizer.
16. Towing the probe at highest speed (1.27 m/s), the gain adjust
was set on the linearizer to obtain a 5-volt output.
17- Towing at half the highest speed (0.64 m/s) produced approxi-
mately 2.5 volts. When the exponent was changed, the temper-
ature compensation was adjusted again.
18. During calibration runs, the RMS output was recorded by reading
the scale; setting the time constant to 10 s produced steady
readings. For example, 1% turbulence gave 0.05 V RMS when the
mean lineage output was 5 volts.
41
-------
APPENDIX F. PRESENTATION OF TEST RESULTS
The following test results tables list the ambient conditions
during testing, probe positions, and linearizer output for each individual
test. The results-oriented individual will be most interested in the
"Intensity RMS/Auxiliary" column, since this is the actual measure of
turbulent intensity encountered by the probe in its various positions
around the boom. The Auxiliary voltage (V) is a measure of the linearizer
output, the RMS voltage (V) being the treated signal of the linearizer
output.
42
-------
TABLE F-l. (Continued)
W
Teat
no*
34
35
36
37
38
39
40
41
42
43
44
45
45R
45R'
45R'
46
47
47R
48
48R
49
49R
50
50R
51
51R
52
53
53R
54
Dace
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
Wind
speed
m/s
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
0.44
0.44
4.24
4.24
5.27
3.35
3.35
3.35
3.35
5.27
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
Wind
dlr.
WNW
WNW
WNW
WNU
WNW
WNW
WNW
WNU
WNU
WNU
WNU
SE
SE
WNW
WNW
NNW
NNW
NNU
NNW
NNU
NNU
NNE
MNE
NNE
NNE
NNE
NNE
ENE
ENE
ENE
Air
temp. Tow speed
•C n/s
29.0
29.0
29.0
29.0
29.0
29.0
29.0
29.0
29.0
29.0
29.0
22.0
22.0
30.0
30.0
32.0
32.0
32.0
32.0
32.0
32.0
33.0
33.0
33.0
33.0
33.0
33.0
33.0
33.0
33.0
0.540
0.540
0.550
1.070
0.270
0.540
1.070
0.280
0.540
0.290
1.060
1.060
1.050
1.050
1.010
1.050
1.060
1.050
1.050
1.040
1.050
1.040
1.030
1.030
1.050
1.050
1.050
1.040
1.040
1.030
Auxiliary
(V)
0.13
0.14
1.22
1.78
0.60
1.15
1.73
0.64
1.24
0.86
1.77
1.12
1.11
1.12
1.05
1.08
1.05
1.05
1.04
1.04
1.03
1.02
1.03
1.02
0.9B
2.07
2.12
0.78
0.74
0.70
RMS full
scale
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.003
0.01
0.003
0.003
0.003
0.003
0.003
0.003
0.003
0.003
0.003
0.003
0.003
0.003
0.03
0.03
0.03
0.03
0.03
RMS
(V)
0.81
0.82
0.20
0.19
0.29
0.19
0.20
0.09
0.40
0.20
0.51
0.98
0.04
0.13
0.18
0.18
0.23
0.21
0.22
0.21
0.22
0.23
0.16
0.18
0.22
0.46
0.48
0.30
0.35
0.27
Intensity
RMS/Aux.
62.31
58.57
1.64
1.07
4. 83
1.65
1.16
1.41
3.23
2.33
2.88
0.30
0.04
0.03
0.05
0.05
0.06
0.06
0.06
0.06
0.06
0.07
0.05
0.05
0.06
0.67
0.68
1.15
1.42
1.17
Probe
X
1.06
1.06
1.50
1.50
1.50
1.50
1.50
1.20
0.91
1.30
1.50
0.73
0.73
0.73
0.73
0.73
2.40
2.40
2.40
2.40
2.40
2.40
2.10
2.10
2.10
1.98
1.98
1.98
1.98
1.60
position, m« Probe relative
y z to boom Comments
0.91
0.91
1.80
1.80
0.91
1.06
0.76
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.30
0.76
0.76
0.76
0.76
0.76
0.76
0.76
0.60
3.50
3.50
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.30
0.30
0.30
0.10
0.66
0.66
0.66
0.30
0.30
0.10
0.10
0.10
0.10
0.30
0.30
0.66
0.10
0.10
0.10
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
No filter
No filter
With filter
With filter
With filter
With filter
with filter
With filter
With filter
(Continued)
-------
TABLE F-l. (Continued)
Test
no.
55
56
56R
57
57R
58
59
60
61
62
63
64
65
Date
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
4/19
Wind
speed
B/S
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
3.35
Wind
dlr.
ENE
ENE
ENE
ENE
ENE
ENE
ENE
N
N
N
N
N
N
Air
temp. Tow speed
*C B/S
33.0
33.0
32.5
32.5
32.5
32.5
32.5
31.0
31.0
31.0
31.0
29.0
29.0
1.040
1.050
1.060
1.060
1.060
l.OBO
1.070
1.070
1.070
1.060
1.070
1.070
1.060
Auxiliary
(V)
0.70
0.79
0.76
0.78
0.76
0.72
0.69
0.68
0.71
0.78
0.79
Q.72
0.68
RMS full
scale
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.02
0.03
RMS
(V)
0.26
0.25
0.22
0.21
0.23
0.22
0.22
0.24
0.23
0.21
0.23
0.24
0.27
Intensity
RMS/Aux.
1.11
0.95
0.88
0.81
0.92
0.92
0.94
1.04
0.96
0.81
0.86
1.00
1.19
Probe
X
1.60
1.60
1.60
1.31
1.31
1.31
1.31
1.21
1.21
0.91
0.91
0.91
0.91
position, ra* Probe relative
y z to boom Comments
0.60
0.60
0.60
0.60
0.60
0.60
0.60
0.60
0.60
0.60
0.60
0.60
0.60
0.30
0.66
0.66
0.66
0.66
0.30
0.10
0.10
0.30
0.66
0.66
0.30
0.10
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
Fore
With filter
With filter
Dye Included
Dye Included
Dye not Included
With filter
With filter
With filter
With filter
With filter
With filter
With filter
With filter
*x-Diatance from strut to center of boom
y-Dlstance from strut to end of boom.
z-Probe depth.
»*See Table 4 for axes key.
-------
TABLE F-l. TEST RESULTS
01
Teat
no.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
18R
19
20
21
22
23
24
25
26
27
26
29
30
31
32
33
Date
3/15
3/15
3/15
3/15
3/15
3/15
3/15
3/15
3/15
3/15
3/15
4/14
4/14
4/14
4/14
4/14
4/14
4/14
4/14
4/14
4/14
4/14
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
4/16
Wind
speed
n/8
6.71
6.71
6.71
6.71
4.47
4.47
3.58
4.02
4.02
6.71
4.47
2.67
3.35
3.35
3.35
3.57
3.57
3.57
3.57
3.57
3.35
3.35
1.34
1.34
1.34
1.34
1.34
1.34
1.34
1.34
3.35
3.35
3.35
3.35
Wind
dlr.
NW
NU
NW
NW
ESE
ESE
ENE
NW
NW
WNW
WNW
WNW
WNW
WNW
WNW
WNW
WNW
WNW
WNW
WNW
NW
NW
NW
NW
NW
NW
NW
NW
NW
WNW
WNW
WNW
WNW
WNW
Air
tenp. Tow speed
•C n/s
8.3
8.3
8.3
8.3
3.3
3.3
1.7
7.2
7.2
10.0
13.3
16.0
17.0
17.0
17.0
17.0
17.0
17.0
17.0
17.0
18.0
18.0
26.0
26.0
26.0
26.0
26.0
26.0
26.0
26.0
29.0
29.0
29.0
29.0
0.555
0.427
0.552
0.552
0.549
0.555
0.555
0.555
0.826
1.064
0.280
0.540
0.420
0.540
0.400
0.280
0.810
0.810
0.890
1.070
0.800
0.560
1.090
0.820
0.280
0.270
0.550
0.830
0.830
1.080
0.280
0.550
RUN
Auxiliary RMS full
(V) scale
2.02
1.88
2.01
2.25
3.94
9.54
1.10
1.85
2.18
3.38
4.05
0.27
0.74
0.46
0.60
0.32
0.20
1.86
1.77
1.85
1.94
1.54
0.97
1.48
1.20
0.48
0.23
0.55
0.39
0.47
0.40
0.75
0.63
ABORTED
0.3
0.3
0.3
0.3
1.0
1.0
1.0
1.0
1.0
1.0
0.3
0.3
0.3
0.3
0.3
0.3
1.0
1.0
1.0
1.0
0.3
0.3
0.3
0.3
0.3
0.1
0.1
RMS
(V)
0.322
0.395
0.340
0.810
0.430
0.790
0.240
0.320
0.320
0.270
0.250
0.300
0.280
0.280
0.300
0.180
0.930
0.370
0.310
0.350
0.330
0.100
0.270
0.390
0.370
0.400
0.300
0.840
Intensity
RHS/Aux.
4.78
6.30
5.07
10.80
10.91
8.28
12.97
14.68
9.47
6.67
27.78
12.16
18.26
14.00
28.13
27.00
RUN
20.90
16.76
18.04
21.43
13.04
14.73
30.00
23.62
30.00
4.00
13.33
Probe
X
0.61
0.45
0.61
1.77
1.82
1.82
12.75
12.75
12.75
12.75
0.76
0.60
0.76
0.45
0.76
1.06
ABORT
0.91
0.60
0.76
0.76
4.50
4.50
4.50
4.50
0.91
0.91
0.45
0.60
0.45
0.91
0.91
position, n* Probe relative
y z to boom Comments
1.27
1.27
1.01
1.06
0.91
1.06
**
**
A*
A*
1.06
1.20
1.06
1.30
1.60
E D
0.76
4.50
4.50
0.76
1.06
0.91
0.60
0.60
0.30
1.80
0.91
0.30
0.30
0.30
0.39
0.39
0.39
0.39
0.39
0.39
0.39
0.39
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
0.66
3.50
3.50
Fo
Fo
Fo
Fo
Fo
Fo
Fo
Fo
For
For
Fore
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
Aft
No filter
No filter
No filter
No filter
No filter
No filter
No filter
No filter
No filter
No filter
Calibrate
Calibrate
Calibrate
Calibrate
No filter
No filter
No filter
No filter
No filter
No filter
No filter
No filter
(Continued)
-------
TECHNICAL REPORT DATA
(Please read /aamctions on the reverse before completing)
EPA-600/2-78-075
I. TITLE AND SUBTITLE
2.
Hydrodynamics of Diversionary Booms
3. RECIPIENT'S ACCESSION-NO.
6. REPORT DATE
April 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
William E. McCracken
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Mason & Hanger-Silas Mason Co., Inc.
P. 0. Box 117
Leonardo, New Jersey 07737
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
68-03-0490
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory-Gin.,
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
OH
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The failure of booms to contain floating oil in currents above 0.5 m/s appears to
be well established. A method suggested to surmount this limitation is to use the
boom in a diversionary mode to move the oil into regions of low currents where contain-
ment and removal can be accomplished. Previous tow tests with booms deployed in a
diversionary mode have shown that oil droplets are often entrained in a flow under the
boom. In these tests, the booms are set at an angle to the direction of tow and do
not extend entirely across the tank. Typically, the length of boom employed in these
tests was 30 m. Failure of the boom to contain oil occurred near the trailing end of
the boom over approximately one-third of the length of the boom.
The U.S. Environmental Protection Agency sponsored a test program at their oil
and hazardous materials simulated environmental test tank (OHMSETT) to study and docu-
ment the near-field hydrodynamics of the trailing end of a diversionary boom. Three-
dimensional flow fields were examined visually, using dye and oil droplets with a
towed underwater video system designed and built as part of the program. Turbulence
intensity was simultaneously documented photographically and measured with a hot-film
anemometer.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Performance tests
Booms (equipment)
Diverting
Water Pollution
Oils
b.IDENTIFIERS/OPEN ENDED TERMS
Spilled oil cleanup
Diverting floating oil
c. COSATI Field/Group
43F
68D
'18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (ThisReport)
UNCLASSIFIED
21. NO. OF
54
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 222Q-1 (9-73)
, , .
U.S. GOVERNMENT PRINTING OFFICE: 1978-757-140/6815 Region No. 5-11
------- |