THE HYDRODYNAMIC RESEARCH FACILITIES of the
NATIONAL RESEARCH COUNCIL
MECHANICAL ENGINEERING REPORT MB-251
By
S.T. Mathews
Division of Mechanical Engineering
March 1963 OTTAWA
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MB-251
THE HYDRODYNAMIC RESEARCH FACILITIES OF THE NATIONAL RESEARCH COUNCIL
This report describes the facilities and work of the Ship Section. It is intended to show the operation of the
Section in a way which might prove useful to those who currently use the facilities or who might have future requirements. Photo-graphs and diagrams have been used mainly for this purpose. The
report may be regarded as the framework of a manual, the text
being in the form of a commentary on the photographs and diagrams. Many of the illustrations have been selected from
routine reports, most of which are of a proprietary nature, i. for particular groups or institutions, and for this reason certain disguises have been made.
There is a multitude of special projects which have been carried out in the laboratory, not all of a hydrodynamic nature but usually with a nautical connection. These are not all recorded here, but some of the more important projects are
represented.
The major part of our operation in the past decade or
so has been of a design support nature and this work will always be considered important, not only in itself, but also for guidance
into the most useful channels for research. The present and future policy of the Section is to deliberately set aside more time for research which can be published widely. A few selected reports which have been released for open circulation are listed at the'end of the report, together with references giving more general information about the National Research Council.
The present description has been loosely divided into nine sections, as follows:
Laboratory Workshops Main Experiment Tank
Temporary Shallow Draft Tank Manoeuvring Tank.
Water Tunnel
Main Seakeeping Facilities
Temporary Small Model Seakeeping Facilities Full Scale Trials
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The following is the list of numbered illustrations with comments.
1. LABORATORY WORKSHOP
1-1. SHIP LABORATORY WORKSHOP
The shop is equipped with standard metal-working machines and, in the basement, there is woodworking machinery.
The model-cutting machine, shown with the model in place, can be used as a general pantograph cutting machine for models up
to 25 ft. x 3.5 ft. x 2 ft. Operation is from a stylus
follow-ing a drawfollow-ing on the adjacent table. A large number of scale ratios between drawing size and model size are available. Wood or wax models can be cut.
Thermostatically-controlled wax-melting tanks for temperatures up to 335°F, with a total capacity of 6000 lb.,-are installed in the laboratory. Currently, most of the models are made from wood as this is most suited to the wide range of tests carried out Wax is used on models for limited testing and where large modifications are anticipated.
The model finishing bay is also shown. Many of the specialized laboratory instruments are manufactured and serviced
in the workshop.
Projects beyond the capacity of the machinery or
number of staff are processed in the main Divisional Workshops.
1-2. GLUE PRESS WITH LARGE MODEL LAMINATIONS
A typical wood model block is shown in place on the
press.
1-3. MODEL PROPELLER SHAFT BOSSINGS BEING CUT ON A STANDARD MILLING MACHINE
The standard machine has been adapted to carry out this work directly from a bossing drawing with much saving in time as compared with hand pattern-making methods.
The next five illustrations, 1-4 to 1-8, show some of the steps in constructing an accurate .propeller. Normally
the
model propellers are of the order 8 in. to 10 in. in diameter. The particular propeller shown here was 18 in. in diameter andPage - 3 MB-251 was. designed. and constructed for use on a manned, high-speed,
search boat.
1-4. PROPELLER PATTERN LAMINATION DRAWING
1-5. PROPELLER PATTERN LAMINATIONS
1-6. PROPELLER MACHINING PATTERN
1-7. PROPELLER MACHINING ARRANGEMENTS 1-8. FINISHED PROPELLER
Normally, the model propeller machining patterns are constructed from a solid block of stabilized plastic-, and
accurately checked using axial offsets in a special checking machine. The casting patterns are made in wax and the metal castings sub-contracted to a commercial foundry. The finished propellers are accurately checked to give correct axial offsets within 0.005 in. and the edge thicknesses checked by enlarged photographs of wax impressions.
2. MAIN EXPERIMENT TANK
2-1. TOWING CARRIAGE WITH PROPELLER OPEN WATER BOAT
2-2. CLOSE-UP OF TOWING DYNAMOMETER AND SOME RECORDING
INSTRUMENTS
2-3. CLOSE-UP OF OPEN WATER BOAT
The propeller open water characteristics ate based on
measurements obtained with the same propulsion dynamometers, used in the self-propulsion test, installed in the open water
boat. The conventional self-propulsion analysis is subsequently
made, using these open Water characteristics. Open water
characteristics are also obtained from water tunnel experiments together with the influence of cavitation. Small differences in the results from tank and tunnel may result due to the difficulties of accurately assessing free-stream velocity in the tunnel. For this reason, the non-cavitating results from the tank are used as a standard, where possible, -and the tunnel results are used mainly to indicate the effects of cavitation.
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2-4: MODEL SELF-PROPULSION DRIVE MOTOR AND DYNAMOMETER
Self-propulsion tests are usually carried out over a range of loadings between ship and model self-propulsion point and over a range of speeds. The information obtained is then useful for assessing the effects on propulsion of over-load conditions such as those due to fouling and moderately bad weather. Special overload conditions are considered for tugs and icebreakers.
-The net six illustrations, 2-4-1 to 2-4-6, show some of the standard forms and diagrams used for summarizing hull geometry, resistance and over-all propulsion results. It
should be mentioned here that an accurate large model-sized hull form plan is drawn on a stable plastic drawing paper for the purpose of constructing each model and for calculating the hydrostatic and other form particulars. In many cases these plans and the measured offsets_ are used as the shiplouilding
standards:
2-4-1. DIMENSIONAL FORM PARTICULARS SHEET
Shows the Main ship particulars and some quantities usefullrin subsequent calculations.
2-4-2. NON-DIMENSIONAL FORM COEFFICIENTS.
Shows the main coefficients siqftifi06nt
in:
resistance and propsin.
24-..
NOND3MENSIONAL RESISTANCE (AND EFFECTIVE POWER) DIAGRAM= where =. pg3/2 v7/6.
-.where
7 =
g1/2 1/6 and V =-IP
- V
then, 3 . plotted as ordinate on V as abscissa. Vv
In order to ,orientate this with the used, Va. Page - 5 MB-251 plot widely
Also shown on the diagram are values of other multiples Of Pv and integer powers of Vs7 which are compatible with Vv, and have practical significance. Knowing the values of ,16 and V for
any displacement, power and speed may readily be obtained from the diagram.
fI
The next three illustrations, 2-4-4 to 2-4-6, show the non-dimensional plottings of thrust, shaft speed and
delivered power from self-propulsion tests. Actual dimensional values of these quantities can quickly be obtained for any speed or resistance loading by multiplying the non-dimensional value by the appropriate reference quantity which depends only on
displacement, i.e.
H.P.) =x (H.p.)
2-4-4. NON-DIMENSIONAL THRUST VS. SPEED OVERLOAD DIAGRAM
2-4-5. NON-DIMENSIONAL SHAFT SPEED VS. SPEED OVERLOAD DIAGRAM
2-4-6. NON-DIMENSIONAL DELIVERED POWER VS. SPEED OVERLOAD DIAGRAM
2-5. FLOW PATTERNS ROUND A SELF-PROPELLED MODEL
The flow lines on the hull, propellers, rudders and other appendages are obtained by the motion of paint mixture droplets along the streamlines when the model is self-propelled
.long the tank.
The test is particularly useful in examining special features of the flow such as break-away, and for positioning appendages such as bilge keels.
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2-6. WAKE SURVEY AT MODEL STERN
The velocity distribution in the boundary layer is
obtained with the pitot rake, the pitot,pressures being
measured with an electronic transducer, each tapping success-ively being connected by means of a remotely-controlled
electrically-operated valve. The use of these results in the water tunnel is shown-later.
2-7-1. MODEL WITH PITOT RAKE WITHOUT PROPELLER
The wake distribution in the propeller disc can more conveniently be measured using a cylindrical coordinate system. The rake shown measures total and static pressures at fixed radii and at any desired angular position.
2-7-2. MODEL WITH PITOT RAKE WITI4 PROPELLER
Velocity measurements in way of the propeller give an important record of the flow conditions, possibly more so than those measured on a towed model, i.e. without propeller. The combination of towed and self-propelled results may be used to assess cyclic propeller forces and moments.
2-7-3 DIVIDING DISC OF PITOT RAKE, AND MANOMETER PANEL The dividing disc is used for setting the angular position of the rake in steps of five degrees. Electronic
transducers are now used more often than manometer panels for recording multiple pressures.
2-7-4 CLOSE-UP VIEW OF PITOT RAKE 2-7-5 VANE WHEEL WAKE METER
These are convenient instruments for obtaining
radial wake distributions on towed models to provide propeller design information. Vanes are available for radii up to 5 in. 2-7-6 TYPICAL RADIAL VELOCITY DISTRIBUTIONS
The curves compare values from vane wheels and from circumferential averaging of pitot results, with and without a propeller. The average wake from a self-propulsion test analysis for this particular model is also shown.
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MB-51
2-8. DIFFERENTIAL PRESSURE TRANSDUCER FOR USE IN WATER (HIGH SENSITIVITY)
'This is-one type of 'transducer adapted for use in'
water. Water pressure is transmitted through a thin elastic membrane to a non-corrosive silicone fluid in contatt with the-basic commercial electronic element.
2-9. OSCILLATING- MECHANISM
The illustration shows the mechanism mounted on
the test carriage and a submerged body being tested: The
mechanism can be used for surface or submerged bodies in static or dynamic modes, i.e. the test body can be subjected to heave and pitch or yaw and sway and recordings made of forces and moments. The resulting stability derivatives can be used for predicting or simulating the behaviour of vessels, as in towing, steering, submarine diving or hydrofoil craft control problems. It is expected that this facility will become of increasing importance in the work of-the laboratory.
2-10. STREAMLINE HOUSING FOR UNDERWATER CAMERA
This has been used for examining the flow of ice around self-propelled model hulls and propellers, and also for recording the directions of streamlines.
The next four illustrations, 2-11-1 to 2-11-4, show some of the arrangements and results in connection with bow manoeuvring jet experiments. The illustrations are not all
for the same model.
2-11-1 DIAGRAM SHOWING INLET AND OUTLET POSITIONS OF BOW MANOEUVRING JETS
2-11-2. MODEL PREPARED FOR BOW JET TURNING TESTS 2-11-3. .JET :THRUSTS FOR GIVEN FLOW RATES
2-11,4. SHIP TURNING ANGLES FOR GIVEN JET THRUSTS
.1.11e, Method Of manoeuvring, using boini.jets'jrom.pumpsj
is a Variation of transverSely-mounted 'DOW
Strews-.
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3. TEMPORARY SHALLOW DRAFT TANK
Shallow draft work for Northern river operations is carried out periodically.
This particular tank was constructed, having dimen-sions 100 ft. x 13 ft. with water up to 3-ft. depth.
The six illustrations, 3-2 to 3-7, show some recent design investigations for a particular service. The main problems are associated with running sinkage and trim, speed and power, and free-board limitations.
The illustrations show some benefits of length in this particular case.
3-1-. SHALLOW DRAFT TANK -FACILITY
3-2. 90-FT. BOAT; DEEP-WATER, 10 1(n., RUDDERS ALMOST OUT OF WATER
.3-3. 90-FT. BOAT, DEEP WATER, 10 FOREDECK. FLOODING
3-4. 90.-FT. BOAT, DEEP WATER, 10.9 Kn.:FOREDECK FLOODING
3-5. 120-FT BOAT, DEEP WATER, .12 Kn.,. FOREDECK DRY
3-6. 120-FT. BOAT; SHALLOW DRAFT' (5 FT.), 5.7 Kn.
3-7. 120-FT. BOAT, SHALLOW DRAFT (5 FT.'), 8.5 Kn.
4. MANOEUVRING TANK
The tank has main dimensions of 400 ft. x 200 ft. x 12-ft depth. Pneumatic wavemakers are being installed along the 200-ft. side. There is a 38-ft. high observation tower,
from which models can be radio-controlled, and photographic records of turning paths obtained. A prototype wavemaker has been installed in the main experiment tank and is now in
every-day use. The wavemakers in the manoeuvring basin will allow investigations to be carried out at various ship-to-wave course angles, and also manoeuvring in waves.
Comparisons are to be made between smooth water turning paths in the manoeuvring tank and those obtained on
an analogue computer using the stability derivatives from the oscillating model mechanism.
If the absolute accuracies of the two methods
compare favourably, many of the tests now carried out in the manoeuvring tank will then be transferred to the computer, although each facility will continue to have an advantage in some particular phase of the work.
The following illustrations show the manoeuvring tank, some model arrangements and the results of some
particular tests.
4-1. THE MANOEUVRING TANK UNDER CONSTRUCTION, AND COMPLETED
4-2. MODEL SET-UP FOR RADIO-CONTROLLED MANOEUVRING TRIALS 4-3. RADIO-CONTROLLED MODEL BEING TESTED
4-4. CLOSE-UP OF RUDDER CONTROLS
4-5. TYPICAL RATE OF TURN RECORD
4-6. RATE OF TURN PLOT FOR A DIRECTIONALLY-STABLE SHIP
4-7. RATE OF TURN PLOT FOR A DIRECTIONALLY-UNSTABLE SHIP
5. WATER TUNNEL
This has proved to be one of our most useful
facilities for investigating a wide range of problems under controllable ambient pressure conditions. The tunnel was built under contract, of stainless steel, the design being made to the laboratory specifications. It was installed by N.R.C. personnel under the supervision of the Ship Section and has been in constant use now for five years.
There is a working section 20 in. x 20 in. x 80 in.
in length, access to which is readily made by the use of quick-release clamps. For example, a propeller can be changed in one
or two minutes without lowering the water level, the pressure at the access port being brought to atmospheric by means of reducing pressure in the dome.
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For any flow rate the velocities at any pos the working section are very nearly constant, and the is considered satisfactory in this respect. Of cours velocity distributions can be produced for particular The maximum water speed in the working section is 40 and the minimum ambient pressure 120 lb./ft? absolute
The main impeller is driven at 1500 r.p.m. 75-h.p. motor, and the test propellers in the working usually 8 in. to 10 in. diameter, may be driven up to r.p.m. with a 15-h.p. motor. The propeller dynamomet measure thrusts up to 185 lb. and torques up to 30 ft A three-component balance is also available measuring forces and moments on test bodies. At the some interesting work is in progress in connection wi dimensional hydrofoils, and cavity flows.
5-1. TUNNEL WORKING SECTION
This illustration shows a special speed log set-up for calibration tests.
5-2-1. DIAGRAM SHOWING PRESSURE TAPPING ARRANGEMENTS ON AN
APPENDAGE
Pressure measurements were made with the appendage on a model both in the experiment tank and when mounted in the water tunnel. The device was also examined under cavitating conditions in the tunnel. The good agreement between tank and tunnel pressures is shown in the next illustration.
5-2-2. SOME TYPICAL PRESSURE DISTRIBUTION RESULTS
The full line is as recorded in the experiment tank and the crosses are from the water tunnel results.
The following eight illustrations, 5-3-1 to 5-3-8, show an investigation into rudder performance which was part of a special design study.
5-3-1. PRESSURE-TAPPED RUDDER MODEL
This shows the rudder mounted simulating part of the hull. The upper section cover plate. The fifty plastic the tapping holes can be seen coming up
in place on a plate plate is the.Working tube connections to to a connector panel, ition of tunnel e, special projects. ft ./sec. by a .section, 3500 er can .-lb.
for
moment thtwoPage -MB-25l
5-3-2. RUDDER ON HULL PLATE BEHIND PROPELLER
5-3-3. RUDDER AND PROPELLER CAVITATION
This shows port and starboard views at a number of rudder angles for a high-speed condition. The cavitation is most impressive to watch as it expands and collapses explosively
at high frequency. The rudder is offset a little from the propeller and the hub vortex can be seen to pass the rudder at the lower angles; it becomes part of the rudder cavitation at
the larger angles. Some of the propeller trailing tip vortices also end on the rudder as they pass. Such phenomena as these are most interesting to see from normal projections of
high-speed movies.
5-3-4. RESOLUTION OF PRESSURES INTO RUDDER FORCES
This diagram shows how side forces perpendicular to the ship's centre line plans can be obtained bY simply- plotting pressures on the centre line projection of the rudder, and then integrating..
5-3-5. RUDDER FORCES
These are forces normal to ship's centre line plane as-measured in the experiment tank. The crosses are points obtained from integrated tunnel pressures merely to establish that the order of the tunnel modelling was reasonable. The
actual rudder forces are also composed of viscous fotces and these were not brought into the tunnel result calculations. 5-3-6. RUDDER TORQUES
Remarks similar to those for the previous illustra-tion also apply here.
5-3-7. RUDDER BENDING MOMENTS
These have been calculated, using the tunnel pressure results. The best rudder having the smaller bending moment was able to produce the same ship's turning force.
5,3-8. DEPTHS OF CENTRES OF PRESSURE
' The following two illustrations, 5-4-1 to 542,; show . the test arrangements used for propeller tests with a'SiMu-l'ated
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5-4-1. PITOT TUBE WAKE SURVEY
. The,pitot rake is the same as was shown earlier for examining the-boundary layer on a model in the towing -tank, as also are the automatically--operated connector valve,
pressure transducer, and recorder shown in the
foreground-5-4-2. HULL PLATE WITH WAKE GENERATING BARS
The bars shown on the, bottom left-hand side of the plate produce ,a wake corresponding to that of the b'oundary
layer MeasUed on the model..
-5-4-3. BOUNDARY LAYER IN TANK AND TUNNEL
The spots show the velocity distribution as obtained in the tunnel as an approximation to that measured in the tank,
shown by a full line. The behaviour of the propeller in this wake distribution was then observed.
Propeller cavitation inception diagrams are drawn by observing the speed of advance coefficient (J value) and cavitation number when various occurrences take place. The
following three illustrations are examples of cavitation
dia-grams. More recently the use of a cavitation number based upon the resultant velocity at 0.7 radius (ccr) has been dropped in favour of one based on circumferential tip speed
(0T) That based upon free stream axial velocity (ccv) is
still also used.
5-5-1. CAVITATION INCEPTION DIAGRAM
The sloped curved grid lines are values of constant
ccv
This particular diagram shows the demarcation lines of face and back cavitation for cavitation numbers below which these phenomena occur. The ship goes down the trajectory shown as speed increases and is in a safe region.5-5-2'. CAVITATION INCEPTION DIAGRAM SHOWING THRUST LOSSES This is the same type
of
diagram as in the previous illustration but with the additional thrust loss informationPage - 13
M-251
5-5-3. CAVITATION INCEPTION DIAGRAM ASTERNThe cavitation characteristics for astern conditions are not usually investigated, but were considered in this
particular case, The results indicate the early occurrence of cavitation when reversing, i.e. cavitation commences at high cavitation numbers under these conditions.
5-6. TYPICAL PROPELLER DESIGN DRAWING
The laboratory is well advanced in the fields of propeller theory, design and experiment, having been involved in many design and research projects during the past decade. A number of computer programs based on the most advanced
propeller theory are available. The effects of heavy loading have been studied by the laboratory and improvements to design methods have been and are continually being made. Form plans
can be supplied, to form the basis for construction plans, taking account of cavitation, strength and any special features required of the propeller.
The illustration is given to indicate the essential features for defining propeller geometry. These are a list of main dimensions and geometric coefficients including radius of gyration, and expanded sections plan showing axial thickness,
and a table of axial back and face offsets. The projected and profile views can be adequately shown in small size on the plan. The laboratory has used and advocated axial offsets for defining propellers for many years, and they are increasingly being used
internationally by propeller manufacturers. The table of off-sets can be used as a standard when checking full size propellers with an appropriate machine. They are also used on the same
basis in constructing the propeller model. The offsets are based on calculating those to the section chord lines and then correcting to the face and back with differences measured on full size section drawings made on stabilized plastic paper. These section drawings are also made available to the manu-facturer for construction and edge checking purposes.
Further to the form plan, it is only necessary to specify details of material, hub internal arrangements, and tolerances. This latter item is successfully receiving much attention by Canadian authorities.
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5-7. PROPELLER OPEN WATER CHARACTERISTICS
These show thrust and torque characteristics from the water tunnel, in this case, with the effect of changing cavitation numbers. Cross plots from the thrust curves have been shown previously as loss of thrust information on the
cavitation inception diagram.
5-8. A PARTICULAR PROPELLER AT TWO CAVITATION CONDITIONS
This shows typical cavitation patterns as developed beyond the half full speed condition for a particular ship for
a constant pitch propeller. As power is increased up to full power the tip cavitation extends down over the back of the blade.
5-9-1. SOME TYPICAL PROPELLER CAVITATION WITH A CONVENTIONAL
HUB AND WITH A DIVERGENT CONE
This approach for distributing the vorticity over a wider cylindrical section of the slipstream for a particular
case was devised by a member of the laboratory staff. By this means the hub vortex is prevented from forming. Another method
for achieving this result, depending on the design details is, when required, in general use in the laboratory.
5-9-2. A PARTICULAR HUB VORTEX CAVITATION DIAGRAM
The results here refer to the propeller of the pre-vious illustration. A large increase in speed is obtained before the hUb vortex is formed. In this particular case it would only occur at speeds well beyond the top speed of the vessel.
5-9-3. THE EFFECT OF DIVERGENT CONE ANGLE FOR A PARTICULAR
PROPELLER
This diagram shows the trend of increasing cone angle to improve performance, again in this particular case.
5-10. MODEL.CONDENSER SCOOP RESEARCH
A model condenser inlet and outlet are mounted into the side wall of a small water tunnel. The circuit-piping is
completed and a flow valve and venturi are incorporated.
The scoop and outlet characteristics are examined by varying tunnel velocity, corresponding to ship's speed, and for different circuit flow rates. A check and extension of published scoop information was being sought in this particular case.
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MB-251-6. MAIN. SEAKEEPING FACILITIES
pneuma.PY-etrlat,
apable:of
producing 2t.. high. waves at frequencies up to one cycle per second, ha8 recently been fitted at the end Of the .main experiment.tank. 6-1. PNEUMATIC WAVEMAKER DOMEThe waves are produced by subjecting the tree surface inside the dome alternately to pressures oscillating above and below atmospheric from the delivery and suction sides of a
50-h.p. axial blower driven at constant speed by an-a-c. motor. The frequency control is made by adjusting the pee. the
flap valve which exposes the dome to one side or other of the
fan.
Amplitude of the wave is reduced, as necessary,
by
opening a:bypass valve in a cross, connection: between the -delivery and suction pipes.'6L2. REGULAR WAVES TRANSMITTED ALONG TANK
6-3. LARGE INSTRUMENTED MODEL PITCHING IN WAVES
Until recently, in the absence of larger facilities, most of the seakeeping tests have been carried out using
special small models 5 ft. to 6 ft. in length.
It is expected that there will be little or no need henceforth for these small models.
7. TEMPORARY SMALL MODEL SEAKEEPING FACILITIES
-This tank was constructed to dimensions 150 ft. x
26 ft. with 5-ft. depth of water. The tests carried out have been mostly on rolling characteristics of vessels and the
capabilities of flume stabilizers. Comparisons have been made with results on the same model as tested in Ottawa and
in a United States tank. The agreement was fair and, as a result, the United States laboratory decided that the refined techniques it was using should be adjusted for more accuracy as accredited to the Ottawa results.
. .
On another occasion,, results- on a small model
-at-. ,.
Page 7 16 MB-251
good comparison. Such comparisons for other tests, have been carried out from time to time over the past decade or so and are a means of improving test techniques and also of inspiring,
confidence in everyone concerned.
7-1. GENERAL VIEW OF TEMPORARY SMALL SEAKEEPING TANK 7-2. CLOSE-UP OF PADDLE-TYPE WAVEMAKER
7-3. STATICALLY AND DYNAMICALLY BALANCED SMALL MODEL FOR SEAKEEPING TESTS
7-4. RECORDING APPARATUS FOR MODEL MOTIONS AND WAVE DATA 7-5. SMALL MODEL WITH ANTI-ROLLING TANKS INSTALLED
7-6. GEOMETRY OF A PARTICULAR ANTI-ROLL TANK PROPOSAL 7-7. EQUIPMENT FOR BENCH TESTING ANTI-ROLL TANK MODELS
7-8. CLOSE-UP OF THE OSCILLATING CRADLE
7-9-1. ANTI-ROLL TANK CHARACTERISTICS
This shows the effect of depth of water on water transfer in a particular configuration.
7-9-2. ANTI-ROLL TANK CHARACTERISTICS
This shows the benefits, in a particular case, of removing weirs and nozzles as they were planned in a first proposal.
7-10. FLUME STABILIZING TANK IN A MODEL
7-11. MODEL ROLLING IN WAVES SHOWING RECORDER CONNECTIONS
7-12. ROLLING RESPONSE CURVES SHOWING EFFECT OF BILGE KEELS
In this particular case the bilge keels were shown to be very effective.
7-13-1. ROLLING RESPONSE CURVES SHOWING THE EFFECT OF
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MB-251
7-13-2. ROLLING RESPONSE CURVES SHOWING THE ADDITIVE EFFECT OF BILGE KEELS
In this particular case the.. benefits bilge keels
Ore superimposed on the benefits due to tanks alone, as shown
in
the previous illustration.7-14-1. ROLLING RESPONSE CURVES SHOWING THE NEGLIGIBLE EFFECT. OF BILGE KEELS IN A PARTICULAR CASE
7-14-2. CORRESPONDING DECREMENT CURVES WITH AND WITHOUT BILGE KEELS
714-3, TANKS ARE EFFECTIVE IN A1PARTICULAR CASE WHERE BILGE
KEELS WERE NOT
7-15-1. ROLLING SPECTRA, ETC. FOR A STATE 6 SEA
This diagram shows the next stage to be cohsidered for obtaining useful information from the rolling response data of the previous illustrations. Similar processes can be carried out using pitch and heave response factors, etc. It
is most interesting to observe that the response factor roll angle
g
i.e.
a , for any particular vessel and frequency
wave slope'
is constant even up to large rolling angles. This fact enables statistical conclusions to be arrived at for any
particular vessel at the appropriate heading in a given sea.
Until recent years, all the classical experiment work on seakeeping has been carried out in regular waves, the procedure being to send down a train of waves of constant
frequency and height and then to repeat the process at another frequency and/or height. Because of the idealized nature of these experiments the results have always been subject to the criticism of lacking reality. The statistical approaches that have been applied in recent years have now supplied proven methods for making use of regular wave experiment data to obtain behaviour predictions in real, i.e. irregular seas. Previous reliable experiment results can now be applied with confidence for such predictions.
In at least one establishment, for each train of experiment waves the frequency and height of successive waves is adjusted; thus the model is subjected in quick succession to different wave heights and frequencies. Such experiment
Page - 18 MB-251
methods have the potential, of reducing over-all experiment time but with the probability of loss of accuracy; the result-ing seas cannot be considered as a realistic representation of a true sea.- The modelling of actual sea conditions for a given period is theoretically possible and in the next few
years may actually be carried out. Although this may be
considered desirable in some respects, it will only have limited scientific importance.
In summary then, it is considered that reliable statistical results for actual sea conditions can now be obtained from model test data in regular seas.
dE
The diagram shows the spectral curve 5731 as proposed
by Newmann for a fully developed state 6 sea. There will be typical sea spectra for any area at a given time of the year and
and such information is being collected throughout the world. Following on from the amplitude spectrum, there is a wave
dE,
slope spectrum
Ti7r,
the high frequency waves having the greatestslopes.
The tolling magnification.factor for the particular vessel
(0/a)
is shown with its peak at the natural .damped'frequency of the vessel.
Applying this response operator to the wave slope dE,
spectrum, the rolling spectrum Ti.-(t is obtained. The rolling spectrum has its peak again at the natural damped frequency of the vessel, reflecting the peak of the magnification factor. A vessel rolling is a very good filtering device, its motion being a magnified reflection of the waves at the vessel's
natural frequency, and the large rolls will be at this
frequency. This magnification is a result of the very small amount of notion damping on the hull. The effectiveness of stabilizing devices is to provide some damping where almost none previously existed, and the result is to cut down the peak of the magnification factor resulting in small roll
angles. The actual wave lengths (Lw), in feet, are also shown
on the diagram.
By, finding the square root of the areas of the
rolling and wave amplitude spectra, various statistical results may now be obtained.
Page - 19 WB-251,
7-15-2. SOME .STATISTICAL RESULTS FROM THE SPECTRAL DIAGRAM FOR A PARTICULAR VESSEL IN A STATE 6 SEA .
Some of the important roll angle and wave height statistics, such as the most frequent, average of the one-third highest, highest expected in 1000 waves, etc., are shown on this diagram, together with the percentage of
oscillations expected in any particular range of roll angle and wave height.
8. FULL SCALE TRIALS
The laboratory has always been active in checking perforMance predictions and examining problems on ships at
sea.
During sea trials, measurements are made of speed, power, shaft speed, fuel consumption, turning paths and rates of turn, rudder angles, steering gear ram pressures, vibra-tions, rolling, pitching, heaving, and towing forces.
Many reports concerned with the analysis, and comparison with experimental and theoretical predictions, have been issued. Equipment is available for recording all of the above items.
Torques can be measured on shafts from 11- in. u
to 18 in.
diameter,-8-1. TORSION METER ARRANGEMENTS
The next five illustrations, 8-2-1 to 8-2-5, show the arrangements for a special investigation into the hydro-dynamic performance of a ship's condenser cooling system. The work was correlated with model tests carried out,in place on a ship model in the main experiment tank, with the water tunnel tests previously illustrated, and with published data.
8-2-1. FULL SCALE PITOT RAKE ASSEMBLY AT CONDENSER sINLET 8-2-2. FULL SCALE PITOT RAKE ASSEMBLY AT CONDENSEOUTLET
8-2-3. FULL SCALE PITOT TUBE CONNECTIONS ,
Page - 20 MB-251
8-2-5. SOME VELOCITY DISTRIBUTIONS IN THE INLET PIPING SYSTEM
8-3. HIGH POWER STROBOSCOPE AND FLASH EQUIPMENT FOR PROPELLER
VIEWING
This equipment has been recently acquired for making propeller cavitation observations at sea which will, it is
expected, provide Importantscientific information regarding their detail performance. This will be important not only for its inherent value but also for critically examining existing model experiment and theory techniques.
9. COMPUTERS
These have been installed for general use by the Division of Mechanical Engineering and are an important and
essential aid to the operations of the Ship Section (essential, in that many calculations and investigations could not other-wise be carried out).
The analogue computer has been used for preliminary manoeuvring and seakeeping simulations and many new investiga-tions are planned.
9-1. ANALOGUE COMPUTER WITH DIGITAL CONVERTER; DIGITAL
COMPUTER IN BACKGROUND
9-2. CONTROL PANEL FOR MODEL MANOEUVRING SIMULATION
The operator can simulate the manoeuvres of vessels from a panel of this type, being able to position hydro plane or rudder angles at set rates, and observe depths, trim angles, etc., or transfer, advances, course angles, etc.
9-3. DIGITAL COMPUTER
These have been useful for carrying out many of the routine calculations normally carried out on desk calculators, but at much higher speed. Many programs in this connection have been written in the laboratory. New, and otherwise impossible, calculations, in particular for propellers, are also carried
out. A recently revised program for calculating ship
hydro-static particulars is available.
An analogue digital converter has recently been fitted to connect the analogue and digital machine, and the theory for making best use of the resulting hybrid machine is now being developed.
The equipment is available for direct use by Canadian industry.
MB 193 MB-221 MB-225 MB-226 MB-227 Page -MB-251 ACKNOWLEDGEMENTS
Recognition must be given to the Royal Canadian Navy, Department of Transport, other Government Departments, and
private companies, who make use of the facilities, and without whose interest most of the work illustrated here woUld not have been possible.
The author is most appreciative of the enthusiasm of the staff of the Ship Section in carrying out their work.
The report has been produced with the encouragement of the Director of the Division of Mechanical Engineering.
SELECTED OPEN DISTRIBUTION REPORTS
"The Velocity Distributions Round
Elliptic
Sections . Due to Thickness and Angle of Attack".G.J. Mainwood. October 1956.
"Cavitation Tests of the 3-Blade Kamewa Controllable Pitch Propeller". J.S.C. Straszak. December 1959. "A Simple Approach to the Mathematical Ship Form".
P.A. Hamill. September 1960.
"Computing Effective Powers and Associated
Coefficients from Ship Model Resistance Tests". P.G. Morel. September 1960.
"A Program for the Calculation of the Hydrodynamic Pitch Angles of Propellers with a Bendix G-15 Digital-Computer.
C.G. Benckhuysen. August 1961.
MB-228 "The Calculation of Propeller Induction Factors: An Intercom 500 Subroutine for the Bendix G-15 Digital Computer". P.A. Hamill. August 1961. MET-257 "Wax Model Construction". R.J. Peters.
Page - 22 .
MB-251
MB-231 "Optimum Length and Illickness of Propeller Blade Sections from Cavitation and Strength
Considerations". S.T. Mathews and J.S.C. Straszak. April 1961.
MET-285 "Water Pressure Transducer". L.I. Kawerninski. April 1961.
MB-237 "A Program for the Calculation of the Circulation Distribution of Propellers with a Bendix G-15
Digital Computer". C.G. Benckhuysen. August 1961. MB-250 "Programs
'for
Calculation of Hydrostatic ParticularSof Ships", Ruby C. Denison. January 1963.
GENERAL REPORTS
The National Research Council of Canada Forty-Fifth Annual Report for 1961-62.
Review of the National Research Council, 1962.
Quarterly Bulletin of the Division of Mechanical Engineering and the National Aeronautical Establishment, December. 1962.
GLUE PRESS
WITH LARGE
MODEL
. 13 , ,s. Vo 4 ,,. \ ' '1/4 ' ;Vt., .% Ns: ,:s-4s,,',
--=
,Ic\I
, s, \ \ \ . \ -,. v. T'''' s MODEL PROPELLER SHAFT BOSSINGSBEING CUT
ON A STANDARD MILLING MACHINE N3 IFIG. 1-6
MB- 251
=AI
TOWING CARRIAGE
WITH
PROPELLER
OPEN WATER BOAT
N141
FIG. 2-1
r-7r-1r
"
C
41. rs / /0 0 ,. j , jt
MODEL SELFPROPULSION
DRIVE MOTOR AND DYNAMOMETER
If:
4-Beam moulded
Displacement beam B.
Draft forward, at Section 20
Draft aft, at section 0
Mean draft, at +Section 10
Volume of displacement
Displacement
L.C. B. aft of fore perpendicular
Speed ci = = 3.3585ve
Force W = gpV 64.040 V,
Torque CI = gpr.. = 64.040 Vr
Shaft Q gosv-usi = 340.33 Viv
speed Power P=W .66045 vr
4.90069
V4 _117. 699576.807
13853.1
67889.7
332,706
FORM PARTICULARS-I
Type Scale Condition 4,00Ship
Customer Neigh SHIP MODELLength between perpendiculars Lep 400..02 ft
ill
199. 875 . inLength on load waterline Lim 400600 ft Ism _1994_864
Displacement length Lw -400. 00 ft lw 199.8614. in
..
Length of parallel middle body L. ft I, 4. in
A ft ft _ 22-. 516
22.516
ft22.516
ft325,17k
_9290.7 r202.67
ftArea of displacement waterplone Aw ft t
C.F. aft of fore perpendicular
Transverse M.I. of waterplane ft.
_21.8504
1m 2.08214.1 *107lbL 43199 .109
ft lb41.0406
min-1780910.06
hpyr:8.29251
fte-5 68.7657 ft z4728.72
ft. 223608 ,107ft4vr
2.69651.106ft.
FIG. 2 MB- 25124.
0168 Model No V = 5.6721 Vr w = 62.364 4 = 62.364 q4,13 7r) 5.672117;:(11 0 353.74 yr bw in in11.250
A, 11. 250 in11. 50
23.473
_ ft3 1464* 71 lb 101.4265 in29,328
108.0
ft2in 1469211 fell V r _ 2 f 8.6322 ft8.1981
171r.
vr
_67.2077 ft' voir39.7188
-77 VWetted surface
30,228
it!52.405
ft,REFERENCE QUANTITIES
Calculated by R. D. Date
Jan. 25/63
p 1.9384 (FW) = 1.9905 (SW) lb ft' sect Checked by C. G_B Date
Jan. P5/63
9.59779
ft sec'463.87
lb14191.34
ft lb_3.35210
sec"FIG. 2-4-2
FORM PARTICULARS 31
MB- 251
Condition
4001 Shin,
Modsl No.Note: Ho is draft
at sect . 10 from base line.
Ax maximum section area at section 9
IT Transverse Beyer
v
ft. HD u22.516 ft
Ax249.20 ft!
LW 2 2111L 85.817
Ca V Z0.6330
VIA) LD BD HD LVBVIIVI72
I :Ca a0.6507
Hq * HD * (L32711Cps
, A 1 Ar
VIA 1-D pix 1..1p.m wpa
BD
0.8295
BD.
BV,
2.533
BV a V V3 HD HT S6.392
LD I-,
7.013
V213 SD By Au Itv
Ax.ii Z
0.2642
C w 2 Avi 0 . 714311-LD BD CM BD HD g B:VHV"727
IT a PAT co .1538 Ax ITV TiVi Lp L.C.B. from LD forward50.67
LD LD Trim % L.0-20 LD BD = LOD HD 3 BDHD LD AX Calculated byR.. Denison
Date.Tan. .25. 1963
'Checked by C G. B5-1-&3.
rt.) CM , sr .104. 0 COW. '-1 1
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-VS.
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'4
0.66853 0.637 0.622 ,0591 0.560 V .17 0.498 0.435 0.37300
11111111INSMININI
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11"
los 3.0 2.5 ZA 1 0.5 1.0 15FIG. 2-4-6
MB-251 9 8 7 6 5 4 3 2 15(SHIP) .1.781 x106._H.P. (SHIP) =27.85 KN.TRIAL CONDITIONTION
*Or
ro
PfAi.
00000-0'0
000
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7%
OVERLOAD 10% 2O% 0 0-5 1-0 PEv 2 v X 10NON-DIMENSIONAL DELIVERED POWER VS.
SPEED OVERLOAD DIAGRAM
I5 0.684 0:653 0.637 0.591 0.622 0.560 0.498 0.435 0.373 HIP II I
MODEL WITH
PITOT RAKE WITHOUT PROPELLERF 16. 2,71
FIG. 2-7-2
MB-251
cvr
4
15, "3 61.-= r. I I.E...14
5
Q9 0.8 0.7 0.6
> 0.5
40.4
>
0.3 0.2 .0.10
a
,PITOT WITH PROP
PITOT WIT ; WAKE METER SELF P 0.1
0.2
0.304
o.5 0.6 0.708
TYPICAL RADIAL VELOCITY DISTRIBUTIONS
0.9,
1 0 Xc ROPUILSION-P. ROUT PRODIFFERENTIAL PRESSURE TRANSDUCER
FOR USE IN
WATER (HIGH SENSITIVITY)STREAMLINE HOUSING
FOR
UNDERWATER CAMERA
COMPONENT PARTS
SET UP FOR
VERTICAL VIEWING
FIG. 2-10
FIG. 2-11-I
MB-251
PLAN VIEW
t. OF NOZZLES -APPROX. 12° FORWARD
OF THE RIGHT ANGLE TO SHIPS t
FROM DWG. NO. 58 -63/10 POSITION OF PUMP SUCTION APPROX. 34 SHIP". r1APPROX.27" MODEL 145 SHIP 72.5" MODEL -0-6.- 0" SHIP 3"MOD 17'WL SHIP 8.5" WL MODEL PART ELEVATION PUMP SUCTION POSITION OF JET NOZZLES 5' -7.5" SHIP 17.813"MODEL STBD. JET NOZZLE F. P F. P.
DIAGRAM SHOWING INLET AND OUTLET POSITIONS OF BOW MANOEUVRING JETS
N.B. NOT TO SCALE
41r-Gr°V--
6:
MODEL PREPARED FOR BOW JET TURNING TESTS
FIG. 2 -II- 2
FIG. 2-11-3 MB-251 i0000 9000 8000 7000 6000 -3 5000 Cr X 4000 3000 2000 100 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I THRUST OF 3.5 TONS 0.9 TD 0 clJ 4:o7N ./ A 0.8 THRUST OF 5000 LB. 2 , :zo '' 0 A: o A. (-1 A 0.7 U,0 f=
a
cc $.5 o 0 $' Tr 0 0 0 4.. 4 A.- 4,-..44.. . A. .. . 0.61_ cn m cc x 1-0.5 A`r-Add
o A'"'
A. 0.4 -.11111111111111111,-1 1olor
14-co 42 Q4. lx*-.::. c, .cillprop
111111411
1000 2000 3000MASS FLOW, 0 (LB./SEC.)
JET THRUSTS FOR GIVEN FLOW RATES
1 1 I. 0 0 0. 0 0. 0. 0. 300 400 T, TIME IN SECONDS 500
SHIP TURNING ANGLES FOR GIVEN JET THRUSTS
LIGHT CONDITION, SHIP STATIONARY
600 700 6 -90 5
Ell
592 9.87/
703 00'/
I 66 .77 = 80 '.... ...e. 1107 6617
- 7 0 RESULTS 40 ° ARE EXTRAPOLATED BEYOND/
04' ..."/
..." .-6 0 VS5 .0' ..Millnill
9le
0 -° El MEG.)ct.
f..°0°. 7 4010"°
e
0 -AIOJIIIIIIIMPPPPP-
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-30 5 i..S 01 -./11 .UU
00/ 'it ...° .- 2 0-I
a -(0 0 WW1 ...Pillill
_ _-DIRECTIONAL
SHALLOW DRAFT TANK
90-FT. BOAT,.
DEEP WATER,.
10 KNOTS NOTERUDDERS ALMOST
OUT OF
WATER90-FT. BOAT, DEEP WATER, 10 KNOTS
-411T41:4 !It , .0.
90-FT.
BOAT, DEEP WATER,
10.9 KNOTS
EXTREME FOREDECK
FLOODING
"r1
-120-FT.
BOAT,
DEEP WATER,
12 KNOTS
120-FT.
BOAT,
5 FT. DEPTH,
120-FT.
BOAT,
5FT. DEPTH,
o
MODEL SET-UP FOR
RADIO-CONTROLLED MANOEUVRING TRIALS
FIG. 4-2
FIG. 4-3
MB- 251
" .2.0%atit. -'-'""r"*,"--
-,-',4,°° _ f." -'boRn. .4.RADIO-CONTROLLED MODEL
BEING TESTED
' -"Ss-4-.47"r.
-"Jr
111111111111111111111 AIL AIL
ilk
ANL A% AL. dirb 401% 4011r. 416.TYPICAL RATE OF TURN RECORD
15 PORT 10 71/2 5 3 or"
FIG. 4-6
MB -251 RUDDER ANGLE 3 5 71/2 10 15 STARBOARDTWIN SCREW VESSEL
SINGLE SCREW VESSEL WITH
RIGHT TURNING SCREW.
FIG. 4-7
MB-251
Zr"
#19/
o TWIN SCREW VESSEL
SINGLE SCREW VESSEL WITH RIGHT TURNING SCREW
cr a.
RUDDER ANGLE
71/2 10 15
STARBOARD
RATE OF TURN PLOT FOR A DIRECTIONALLY-UNSTABLE
SHIP15 10 71/2
oozes,.
al.Jli Aywa.s.... - /- : i '''. 1'
r -1'7 ,-.1:. .. - .. 4, .:L.11nat.c.r ISMTUNNEL WORKING SECTION
,
v3r-FIG. 5-1
FIG. 5-2-1
MB- 251
PRESSURE TUBE
ADAPTER PLATE
9.1 IN.
Of 20-IN. X 20-1N. WORKING SECTION
DIRECTION OF
FLOW-.PRESSURE TUBING TO
MANOMETER BANK
SECURING BLOCK
ALUMINUM WINDOW
LOCATION Of STATIC PRESSURE TAPPING
DIAGRAM SHOWING PRESSURE TAPPING ARRANGEMENTS
ON AN APPENDAGE
0. 0. 0 0. 0. 0. SECTION J 1 8 MODEL CAVITATION BASIN TUNNEL X 6 4 2. j...---.. )1e 0 ' x 9 10 9 8 7 6 5 4 3 2 0
SOME TYPICAL PRESSURE DISTRIBUTION RESULTS
FIG. 5-3-3
MB- 251
esS
TRAILING EDGE OUTBOARD
15° -30° 45° ',Ate
-RUDDER AND PROPELLER CAVITATION
00
RUDDER SURFACE
RUDDER AXES
ds COS a 2
FORCE NORMAL TO SURFACE p ds
COMPONENT IN DIRECTION OF Y g p ds COS a p dx
X-AXIS
0160110
RESOLUTION OF PRESSURES INTO RUDDER FORCES
FIG. 5-3-4
MB-251
1°t4
FIG: MB -:251' 250 200 CI)
8
IX 160 50 oo 10 20 30RUDDER ANGLE DEGREES
RUDDER FORCES
FIG. 5-3-7
MB 251
i-z
2
0
co 0130 400 500 XTRAILING
!III
EDGE OUTBOARD TRA1U NGJII
EDGE INBOARDI
40 30 20 10 0 10 20 30 40
RUDDER ANGLE DEGREES
RUDDER BENDING MOMENTS
RUDDER
B _X
.8
.2
DEPTHS OF CENTRES OF PRESSURE
Id FIG. 5-3-8 MB- 251 p. I X RUODER RUDDER I B C I I ft
I
*
X oX It It*
I TRA1UNG EDGE 1 OUTBOARD I TRA1UNG I EDGE I INBOARD6
Id IdII-0
t
n. 10 20RUDDER ANGLE DEGREES
FIG. 5- 4-3
MB -251 4TIT
0 - BOUND PRODUCED I ODEL TION SHIP M FLOW DIREC BOUN ARY LAYER N WATER TU -0 NNEL. OAR" LAYER0
2 4 6 .8 10 12 14 V (FT./SEC.)a
24 20 16 . 8 7 a ON SPEED ON RESULTANT RADIUS OF OF ADVANCE PROPELLER c6 is( 1 . ac BASED R 2 CE BASED AT 0.7 .fV0;121
mai
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DESIGN DRAWING 121. I " 02 0411PM/ 61,1412 We 011110 afaa _07 ne 42. 011 OM .19 Ste 104 4. .1 1 _ I _ °- I 01143.5 0.70 2.5 2.0 1.5 1.0 0.5
PROPELLER OPEN WATER CHARACTERISTICS
FIG. 5-7 MB- 251 lo
P
4
mil
E
Oil
1 1
AL,
NA
111M
11
r SI
WARN
Elle
AKE
AI
E
PIM
II
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MM.
11101
ILI
IN
101
NM
KG
05
06
07
0$
09
10xKT 100x K 0.65 0.60 .55 .50FIG. 5 - 8
MB - 251
HALF SPEED
HALF POWER
-CONVENTIONAL HUB
DIVERGENT CONE
SOME TYPICAL PROPELLER CAVITATION WITH A CONVENTIONAL HUB AND WITH A DIVERGENT CONE
J: 1.07; acr 0.27
FIG...5-9-1
1.0 09 0.8 0.7 0.5 04 0.3 0.2 01 Di v RGEN r CONE
op
1.1 12 1.3 1.4A PARTICULAR HUB VORTEX CAVITATION DIAGRAM
_ .
FiG. 5-9
2 cra.MB-25I
5.0 VA ADVANCE COEFFICIENT n 4.0 Po CAVITATION NUMBER cTcr 3.04 p
[i
SHIP SPEED IN KNOTS
= CAVITATION NUMBER
J 3 PROPELLER ADVANCE COEFFICIENT
a SEMI-ANGLE OF DIVERGENT CONE
INCREASING J
THE EFFECT OF DIVERGENT CONE ANGLE FOR A
PARTICULAR PROPELLER
FIG. 5-9-3
PNEUMATIC
WAVEMAKER DOME
,0
r
LARGE INSTRUMENTED MODEL PITCHING
v.,
FIG. 7-3
MB- 251
STATICALLY AND DYNAMICALLY BALANCED
SMALL MODEL FOR SEAKEEPING TESTS
61, tin ftaemawar I
itit
4,-1/ . 7 '
,:+10 0 1 0 At,
It
0 d' q) at, 0. .,_4,,,,
eal *'
7,
3 to;., 9.e
,400I*.;
*:)
1 o oCo
- -LAW-dik.5a:g.2:'7a. RECORDING APPARATUS FOR MODEL MOTIONSFIG. 7-5
MB- 251
26 FT. 4 FORWARD TANK 6 FT 1 I 1 39 FT. FRAME 41 FT. FIG..7-6 FRAME
GEOMETRY OF A PARTICULAR ANTI-ROLL TANK PROPOSAL
MB-251
FRAME
FIG.
MB -251
'
4
0
w 2.4 a. Lii IL 2.0 crz i.6
cr w < 4 Z 0 c7 LL .4 0.8 cr w u-2 inZ IX W 04 I- I- 1G I- Z 02 MO CALE X=5 DEL S 4 6 8 . 10 12 EXCITATION PERIOD SECONDSANTIROLL TANK CHARACTERISTICS
01 I '
ID
14 16 182.
FIG. 7-9-2
MB-25I
SCALE 1/64
ANTIROLL TANK CHARACTERISTICS
WEIRS I AND NOZZLES REMOVED 1 0 o cl w a. w C-,
z
az
0 cn 41111I 4.1 cc _1 _I o iz a. E U) TANK WEIR 25 10 15 20FLUME STABILIZING TANK
IN
MODEL ROLLING IN WAVES
SHOWING
RECORDER
CONNECTIONS
-FIG. 7I2
MB 251 14 12 2 SHIP CONDITION A TONS GM 3.03 FT. NO BILGE KEELS WITH BILGE KEELS 0.708
09
1.0 II 12NONDIMENSIONAL FREQUENCY cctin
ROLLING RESPONSE CURVES SHOWING EFFECT OF BILGE KEELS NOTATION
ROLL ANGLE ( AMPL ITUDE )
a :MAXIMUM SURFACE WAVE SLOPE
w WAVE FREQUENCY
DAMPED NATURAL FREQUENCY
OF SHIP
SHIP CONDITION NOTATION
TONS
GM = 3.03 FT.
k 16.67 FT. IN AIR
TANKS INOPERATIVE
ROLL ANGLE .( AMPLITUDE)
a MAXIMUM SURFACE- WAVE SLOPE
WAVE FREQUENCY
DAMPED NATURAL FREQUENCY
OF SHIP =0.512 RAD/SEC.
WEIRS REMOVED
WEIR ° TANKS
0.7 0.8 0.9 1.0 1.1 1.2 1.3 14 1.5
NONDIMENSIONAL
FREQUENCY-ROLLING RESPONSE CURVES SHOWING -THE EFFECT
OF STABILIZING TANKS
FIG.
FIG. 7-I52
MB- 251:
: 0
I
hi\
SHIP CONDITION TONS GM: 3.03 FT k:16.67 FT IN AIR TANKS INOPERATIVE NOTATIONROLL ANGLE (AMPLITUDE)
MAXIMUM SURFACE WAVE SLOPE
(4) r. WAVE FREQUENCY
W: NATURAL FREQUENCY
OF SHIP 0.526 RAD./SEC.
"WEIR" TANKS
07 0 8-
09
1.0II
1.2 1.3 1.4 1.5NON --DIMENSIONAL FREQUENCY co
ROLLING RESPONSE CURVES SHOWING THE ADDITIVE
SHIP CONDITION
FIG. 7-14-1
MB-25I
NOTATION:
9S ROLL ANGLE ( AMPLITUDE)
G : MAXIMUM SURFACE WAVE SLOPE WAVE FREQUENCY
DAMPED NATURAL FREQUENCY OF SHIP
ROLLING RESPONSE CURVES SHOWING THE NEGLIGIBLE EFFECT OF BILGE KEELS IN A PARTICULAR CASE
14 12
-sic
10 re 0 u_ 8 0 i= 6 2 1 0 CC 4 2 TONS GM 5.91 FT. NO BILGE KEELS ITH BI LGE KEELS 0.708
09
10II
1.2 1.3 1.4 NON-DIMENSIONAL FREQUENCY wn-0-3.0 1.5 ID 0o
X:64
12 14 16 2 4 6 8 10MEAN ROLL AMPLITUDE 1/2 (n4" On+ ),
DEG.
14 12 - SHIP CONDITION: A GM =5.91 FT.
MEM
WITHOUT TANKS WITH TANKS NOTATION:-ROLL ANGLE (AMPLITUDE) a =MAXIMUM SURFACE WAVE SLOPE
:WAVE FREQUENCY
= DAMPED NATURAL FREQUENCY OF SHIP
FIG. 7-14-3 MB- 251
0.7 0.8 Q9 10 1.1 1.2 1.3 1.4
NON DIMENSIONAL FREOUENCY(ifn'
.TANKS411E EFFECTIVE' IN A .I6ARTiCULAR CASE WHERE BILGE KEELS WERE NOT
MB -251 .
NOTE- NATURAL DAMPED PERIOD OF VESSEL
TAKEN AS 9 SEC.
ROLLING SPECTRA, ETC. FOR A STATE 6 SEA
VESSEL BROADSIDE ON TO STATE 6 SEA
CORRESPONDING TO 24 KN. WIND SPEED
13
II
5 3
10% between 10% 10 % 10 % II 10 % 10 % 10% 10 °/o SI 10% 10 % greater than dEa 518 - 2g2
d0/ u/6 e usew2 (Neumann) Ft. and Sec. Units
dEa _ 477'2 slEa_
dui -L VI da)
clEA, dEcr
dw. dw
Root Mean Square Roll
=,\/./
CIEjo)
dcv
0
STATiSTICAL ROLLING AND WAVEHEIGHT PROBABILITIES (NARROW SPECTRUM)
ck° H(Ft.) Most frequent .705 R.M.S. 4.1 6.2 Average .885 R. M.S. 5.1 7.8 Average of 1/3 higest 1.415 R.M.S. 8.2 12.4 Average of 1/10 higest 1.80 R.M.S. 10.4 15.8 Average of 1/100 higest 2.36 R.M.S 13.7 20.7
Highest expected for 100 waves 2.28 R.M.S 13.2 20.0
Highest expected for 1000 waves 2.73 R.M.S. 15.8 23.9
ck° H( Ft.) O a _32 R.M.S. 0 0- 2.8 .32 8 .46 R.M.S. 1.9 -2.7 2.8 - 4.0 .46 a .60 R. M.S. 2.7 -3.5 4.0 - 5.3 .60 a .71 R.M.S. 3.5-4.1 5.3- 6.2 .71 a .83 R.M.S 4.1-4.8 62 - 7.3 .83 13 .96 R.M.S 4.8-5.6 7.3- 8.4 .96 a 1.10 R.M.S 5.6-6.4 8-4- 9.6 1.10 81 1.27 R.M.S 6.4-7.4 9.6- 11.1 1.27 8 1.52 R.M.S 7.4-8.8 11.1 - 13.3 1.52 R.M.S 8.8 13.3
SOME STATISTICAL RESULTS FROM THE SPECTRAL DIAGRAM
FOR A PARTICULAR VESSEL IN A STATE 6 SEA
FIG. 7.152
MB 251
FULL SCALE- PITOT RAKE ASSEMBLY AT
CONDENSER INLET
FIG. 8:-2-t
FULL SCALE PITOT RAKE ASSEMBLY
ATMO=
ALI
CONDENSER
6 STATICS
MAIN: CIRCULATING. PUMP
7 SINGLE TUBES
( WATER )
;
1
0
13 DOUBLE TUBES ( TETRABROMOETHANE )
:13 PITOTS
VENT
VALVE
OVERBOARD DISCHARGE
DIAGRAM
SHOWING MANOMETER INSTALLATIONS FITTED ON VESSEL
.14 l-1
0.0 0 DD 0
12 DOUBLE tuaEs (MERCURY)
ALL CONNECTIONS TO OUTER TUBES
VENT VALVE IL 0 El - - - 10 OF 1 1 1
)4' /1/44ti.
. /25, .OTS - 5 STATICSAlkhommall...._
DOUBLE TUBES 10 DOUBLE TUBES (TETRABROMOETHANE SCOOPRUN I SHIP SPEED SYSTEM FLOW KNOTS G. PM. RUN 2
SHIP SPEED KNOTS
SYSTEM FLOW G. P M.
SOME VELOCITY DISTRIBUTIONS IN THE INLET PIPING SYSTEM
CONTOURS OF Vig ON CROSS SECTION OF CIRCULATING PIPE VIEWED FROM PUMP SIDE OF SCOOP
RUN 3 RUN 25
SHIP SPEED ,KNOTS SHIP SPEED KNOTS
HIGH POWER STROBOSCOPE & FLASH EQUIPMENT
-C -:1 ..,
.
tE.::-.,-^4', = --., -4,17Q 0114, IV4P14#44
4, ANALOGUE COMPUTER WITH DIGITAL CONVERTER DIGITAL COMPUTER IN BACKGROUND 7-11111111-r
_ W ---,. "g4 r . 4e ...powwow.CONTROL PANEL FOR MODEL MANOEUVRING SIMULATION a a" a a v,
e 1f .'"' tyruifiro -0j11110RIO mmt If 7 FIG. 9-'3