Boundary layer control on a ship’s rudder

REPORT No. 135 S

May 1970

(S2/138)

NEDERLANDS SCHEEPSSTUDIECENTRUM TNO

NETHERLANDS SHIP RESEARCH CENTRE TNO

SHIPBUILDING DEPARTMENT

LEEGHWATERSTRAAT 5, DELFT

*

BOUNDARY LAYER CONTROL ON A SHIP'S RUDDER

(GRENSLAAGBE1NVLOEDING BIJ EEN SCHEEPSROER)

by

IR. J. H. G. VERHAGEN

Netherlands Ship Model Basin

Het onderzoek naar middelen ter verbetering van de manoeu-vreereigenschappen van schepen bij lage sneiheden is, vooral sinds het in de vaart komen van de zeer grote tankers, zeer wense-lijk geworden.

Len van de middelen waarvan een verbetering in dit opzicht verwacht mag worden, is de verhoging van de dwarskracht van het roer.

Grenslaagbeïnvloeding door het uitblazen van eco luchtstraal over de intredende zijde van de verstelbare flap van een draag-vieugel, is in de aerodynamica zeer bekend. Dod is het aanhiggen van de stroming over de flap te bevorderen, waardoor loslating naar hogere waarderi van de invalshoek van bet proflel verscho-ven wordt (Boundary Layer Control).

Bij vergroting van de uitblaasenergie ontstaat een zgn. ,fluid flap", waardoor de effectieve koordlengte van het proflel toe-neemt en de lift dientengevolge vergroot wordt (Circulation Control). Dit principe kan eveneens worden toegepast op een roer.

De benodigde pompcapaciteit voor het uitdrijven van de water-straal door de spleet aan de achterzijde van het roer zou bu tankers kunnen worden geleverd door de ladingpompen. Het debiet van een voor dit dod gebruikelijke pomp is als maximum gebruikt bij de variatie van de uittredende watersnelheden. Ook echter bíj beduidend lagere uittreedsnelheden werden belangrijk hogere liftcoëfficiënten gevonden vergeleken met die bu het con-ventionele roer.

Bij manoeuvreerproeven op modelschaal, wel.ke naast de vrij-varende proeven werden ondernomen, bleek dat een met een aldus gemodificeerd roer uitgeruste tanker veel kleinere draai-cirkels kan volvoeren dan een zelfde schip met een conventioneel roer. Bovendieru bleek de diameter van de draaicirkel kleiner te worden naarmate het debiet van het toegevoegde water door de spleet en de hoek van de vin met de koorde van het roerproflel werden vergroot. De winst in manoeuvreerbaarheid bleek het meest evident te zijn bij de kleinere roerhoeken.

Al of niet in combinatie met andere mogelijkheden, zoals bu-voorbeeld boeg- en hekdwarsbuizen, kan het in het rapport be-schreven roer een belangrijke bijdrage leyeren om de gerezen problemen ten aanzien van de maruoeuvreereigenschappen van enkele scheepstypen wat dichter bu een oplossing te brengen.

Voorwaarde is echter dat de praktische bezwaren welke inge-bracht kunnen worden bu de werkelijke constructie van een dergelijk roer, ondervangen kunnen worden.

1-SET NEDERLANDS SCHEEPSSTUDIECENTRUM TNO

The investigation to improve the manoeuvring properties of vessels at low speed became very desirable, especially since the entering into service of ships of the mammoth tanker type.

An improvement in this respect may be expected in increasing the cross force of the rudder on the ship.

The principle of boundary layer control by blowing air from a slit located at the leading edge of a controllable flap of a wing profile, is well-known in aerodynamics. The aim is to ensure flow attachment on the flap, in order to delay the stalling angle.

With further increase of intensity of blowing, the jet sheet forms a fluid flap which imparts a certain degree ofdeflection on the outside flow i.e. the lift increases by circulation control. The same principle can be applied to a ship's rudder.

For tankers the pumping capacity for expelling the water through the slit on the trailing edge could be supplied by the cargo pumps. The capacityofa usual pump is chosen as a maxi-mum limit in the variation of the amount of expelled water. However, even with rather low water speeds higher lift coeffi-cients are found compared to the rudder commonly used.

In addition to the free running tests manoeuvring trials on model scale have been undertaken. They showed that a tanker fitted out with an modified rudder was able to perform turning circles with much smaller diameter than could be attained using a normal rudder. Moreover it appeared that dependent of the amount olexpelled water through the slit and the flap-angle with the chord of the rudder, the gain in manoeuvrability was most evident at smaller rudder angles.

Apart or in combination with other possibilities (for example bow- and stern thrusters) the modified rudder as described above may contribute to the solution of some encountered manoeuvring problems, provided that it will be possible to remove the dif-ficulties which will arise with the construction of this type of rudder.

THE NETHERLANDS SHIP RESEARCH CENTRE TNO

CONTENTS

page

List of symbols

6

Summary

7

i

Introduction

7

2

Description of the testing procedure

7

2.1

The rudder

7

2.2 The ship

9

2.3 Test configurations

9

2.4 Steering tests

9

3

Basic principle of boundary layer control

IO

4

Design data for rudder with fluid flap

11

5

Comparison of test results with the theory

11

6 Conclusions 12

References 12

Appendix I. Example calculation

13

LIST OF SYMBOLS

e

Distance from rudder stock to centre of lateral effort

h

Height of rudder

/

Length of rudder

n

Rate of revolution of propeller

r

Rate of change of heading

s

Width of slit on one side of jet flap

A

Rudder aspect ratio

AR

Lateral area of rudder

C0

Drag coefficient

CL

Lift coefficient

CM Moment coefficient

CT

Load coefficient

C,

Momentum coefficient

D

Drag or propeller diameter

KT

Thrust coefficient

L

Lift

Length between perpendiculars

Q

Volume flow of jet

T

Propeller thrust

V

Ship speed

V0,,, Velocity of approach

VA

Velocity at screw disk

V1

Velocity of jet

V,,

Velocity at trailing edge of rudder

VT

Constant velocity during turn

<R

Rudder angle

Flap angle

Mass density

i

Introduction

High lift devices have been used successfully in the

field of aviation since the early 1920's. Many various

devices, both active and passive, were tried in the past,

but all attempted to increase the lift of a foil by

mechan-ically prolonging the point of separation. This is often

achieved by controlling the boundary layer thickness

by means of suction or vortices generation. A second

way can be found by increasing the circulation through

an extension of the chord length by means of a fluid

jet expelled from the trailing edge. lt was thought that

such a device, if incorporated into a standard ship's

rudder, might improve the man oeuvring characteristics

of the ship. This would be highly advantageous,

espe-cially for mammoth tankers travelling at low speeds.

The Netherlands Ship Research Centre sponsored

the Netherlands Ship Model Basin (N.S.M.B.) in

Wa-geningen to investigate the potential of such a rudder.

The tests were carried out in both the wave and current

laboratory and in the shallow water basin at N.S.M.B.

2

Description of the testing procedure

Basically two types of tests were carried out. First a

rudder equipped with a mechanical device to increase

the lift and moment was tested in an "open water"

condition. This was primarily done to have a

calibra-tion between the test results to those predicted by

theory. Forces and moments on the rudder were

mea-sured during this investigation. After that the rudder

was placed in its conventional position behind a self

propelled model of a 100,000 dwt tanker. A serie of

spiral tests was carried out to determine the

effective-ness of the new rudder as a ship control surface.

2.1

The rudder

The semi-balance rudder was equipped with a slot

BOUNDARY LAYER CONTROL ON A SHIP'S RUDDER

by

IR. J. H. G. VERHAGEN

Swn,nary

The results of an investigation concerning the effectiveness of a ship's rudder equipped with a Boundary Layer Control Device on the trailing edge are presented here. The water jet which is directed by a flap tends to increase the circulation and hence increases the lift force on the rudder.

The rudder was first tested in an open water condition. The results are compared to theory which has been evolved from wind tunnel test performed by various aircraft designers.

The rudder was then fitted to a model of a 300,000 tons tanker.

The rudder angle, flap angle, quantity of water jet and ship velocity were all varied independently. The effects of these parameters on the manoeuvrabílity of the model were traced. In all cases the turning diameter for the model, travelling at low speeds in the full loading condition appreciably decreased by using the jet flap rudder.

Fig. 1. Sketch of the water jet rudder

The principal dimensions of the rudder:

in open water condition behind the ship model

7

height 400 mm 235.5 mm length 258 mm

154 mm

thickness 49 mm

28 mm

flap length 20 mm

10 mm

slit width 1 mm 0.5 mm

8

down the trailing edge. Water was pumped through

1.

the rudder stock and spurt via this slot in the form of

a sheet of water. This sheet, or jet, could be directed

by means of a trim tab built into the slot. Details of

the high lift rudder construction can be seen in figure 1.

2.

The sheet of water which was pumped from the trailing

edge affected the characteristics of the rudder in the

3.

following way:

Fig. 2. Perspex rudder with water jet flap.

Fig. 3. Detail of jet flap.

The high velocity of the fluid at the trailing edge

directed by the trim tab tended to control the

boundary layer growth over the foil, thus giving a

higher lift due to increased circulation.

The jet of water produced a favourable thrust

similar to an active rudder.

The sheet of water essentially increased the effective

lateral area of the rudder. (see fig. 2 and 3)

2.2 TIte s/i/p

A ship model was chosen of which the form and fullness

(CB = 0.802) were typical for modern tankers of

100,000 dwt. (see fig. 4)

To minimize the errors due to scale effect, a large

model was desired. However, due to the physical size

of the wave and current laboratory the model should

not exceed 7 meters in length. The principle dimensions

and the form characteristics of the chosen model No.

2118 can be found in table I. The model scale ratio was

1:39.5.

Table 1. Principal dimensions of the tanker model and propeller

model

Propeller model

2.3

Test configurations

The open water tests were carried out in the shallow

water basin with a water depth of 1.0 meter. The foil

was totally submerged in an upright position in such

a way that the upper edge was 4 cm below the water

level. The foil was attached to the test carriage by means

of a strut. A centrifugal pump forced water down the

strut and out of the slot in the trailing edge. Lift, drag

and moment about the rudder stock were measured by

means of straingauges mounted on the strut. The

vol-ume of the water jet was measured reading of the

pressure difference over a venturi.

In order to compare the characteristics of such a

device operating in water to theory, which in the past

has been based on high lift foils operating in air,

ex-tensive open water tests were carried out. Speed of

advance, rudder angle, trim tab angle and water jet

quantity were all varied independently over wide ranges.

By means of cross-fairing the data, it was not necessary

to test all possible combinations of variables.

Table Il indicates the range of variables which were

investigated. En the diagrams i to 7 of the Appendix II

the test results are presented.

Table Il. Range of variables

2 m/sec 0.5 rn/sec

2.4

Steering tests

The tanker model was equipped for self-propulsion

tests. The high lift rudder fitted into position as shown

in fig. 4. In the model a centrifugal pump was placed,

which supplied the desired quantity of water to the

rudder via the rudder stock. This quantity of water

satisfied the condition that the ratio of the jet velocity

and the screw race velocity for the model and the ship

are equal. By means of gyroscopes and telemetric

equipment, the following quantities were recorded:

- Velocity of model,

- RPM of propellers,

- Rudder angle,

- Flap angle,

- Quantity of water jet,

- Rate of change of heading.

Turning tests were performed to obtain information

concerning ship manoeuvrability with and without the

flap jet. The turning diameter of the ship could be

Fig. 4. Bodyplan of tanker model and stern-rudder arrangement.

Speed of advance V

9

Diameter 232.73 mm

N Limber of blades 4

Pitch at root 140.91 mm

Pitch at blade tip 175.46mm

Pitch at 0.7 radius 170.77 mm

Expanded blade area ratio 0.624

Direction of turning right-handed

Tanker model

Jet quantity Q

Length between perpendiculars 7.0940 m in m3/min x l0 0, 84, 167, 245 0, 73, 127

Breadth 0.9420 m Rudder angle ÒR

Draugth 0.3757 m in degrees 0.5,10,15,20,25.30 0, 5, 10, 15, 20, 25, 30

Displacement 2012.74 dm Flap angle ÒF

Wetted surface 10.1013 m2 in degrees 0, 15, 30. 45 0.30

lo

calculated as a function of the approach speed. The

rudder angle, flap angle, quantity of the water jet and

approach speed varied systematically and again, by

cross-fairing the resulting data, it was not necessary to

test

all

possible combinations of the parameters.

Table III outlines the conditions of the tests as carried

out. In the diagrammes 9 and 10 of Appendix lithe

test results are represented.

Table Hl. Conditions during steering tests

3

Basic principle of boundary layer control

A sheet of water expelled under pressure from a

span-wise slit over a flap at the trailing edge of a foil results

in the phenomena called boundary layer control and

super circulation. With a relatively low jet velocity,

however, still in excess of the surrounding velocity,

separation is delayed by increasing the momentum of

the boundary layer. With attached flow over the flap,

the lift coefficient predicted by potential flow theory

can be realized. The increase in lift, up to that predicted

by potential flow, can be attributed to boundary layer

control. If the quantity of water jet is increased beyond

this critical amount, still further gains in lift can be

"C

Trailing edge separation

obtained. This gain is called supercirculation due to the

presence of a distributed sink and a physical extension

of the chord length. The parameter employed in the

study of flap jet high

lift boundary layer control

systems, designated by the momentum coefficient (Ç),

is a measure of the energy put into the system via the

jet. The momentum coefficient required to obtain the

theoretical lift coefficient (without jet) according to

classical airfoil theory is called the critical momentum

coefficient (Ç, cnt). Supercirculation exists if a

momen-tum coefficient is reached which is in excess of Ç cnjt

One should expect increased turning moments on

the rudder due to the increased effectiveness of the

trailing edge when such a jet flap is employed.

A jet flap on the trailing edge, however, only helps

to control the boundary layer if separation is initiated

at the trailing edge. If the maximum CL is limited due

to separation occurring at the leading edge, then

addi-tional devices such as leading edge slots or flaps must

be employed.

Leading edge separation is more likely to occur on

thin hydrofoils (thickness-chord length ratio smaller

than 5%) while trailing edge separation is usual on

thick profiles such as rudders. This is because the

boundary layer tends to separate when the pressure

distribution in the flow direction has a steep positive

gradient. (see fig. 5)

An exploratory investigation was carried out for a

number of leading edge devices. The relatively small

gains which were incurred indicated that separation on

the leading edge did not exist. It should be mentioned

that the symmetrical devices (i.e.: designed for both

port and starboard rudder angles) gave noticeably

poorer lift drag characteristics than the conventional

rudder.

L.eading edge separation Fig. 5. The effect of the pressure distribution on the boundary layer separation.

calculated from an inviscid theory experiment (qualitative distribution)

Velocity of approach 1ì; in rn/sec Water depth in m Rudder angle ÒR in degrees Flap angle in degrees Water jet quantity Q in m/rnin x 1O 0.49 1.03 35 o t) 40 t) 35 44.7 40 44.7 0.253 1.03 35 0 0 40 21.6 40 32.7

4

Design data for rudder with fluid flap

The maximum quantity of water available at the jet

was limited to the amount of waler which the cargo

pumps aboard a 100,000 ton tanker can supply. In this

case that amount was taken at 12,600 m3/hour. It is

not possible to scale this quantity merely down in the

conventional manner. It is the relative velocity which

influences the boundary layer control. That is to say

the ratio of the jet velocity to the velocity of water in

the screw race at the trailing edge of the rudder must

be equal for both ship and model. Due to the differences

in friction coefficient between ship and model at low

speeds, the model propeller is overloaded during the

manoeuvring tests.

The overloaded propeller increases the race velocity.

Therefore, to keep the relative velocity ratio constant

between the race and the jet, the quantity of flow to

the jet must be higher for the model than for the ship.

In the appendix an example calculation is given,

illus-trating the method and approximations used to

deter-mine the jet quantity for both the ship and model at a

ship speed of 6 knots. The result of the calculation is

summarized in table 1V.

Table 1V. Model 2118 0.49 rn/sec 0.30 rn/sec 0.77 rn/sec 5.3 2.35 rn/sec 3.05 100.000 ton tanker 3.08 rn/sec 1.84 rn/sec 3.12 rn/sec 1.72 9.5 rn/sec 3.05

The power required to create the water sheet and to

overcome the friction losses in the supplying pipelines

can be estimated as follows:

power = kinetic energy in jet + friction losses in

supplying pipelines ± losses due to water

head.

The last two terms are dependent on the individual

piping and are in general small compared to the first

term. So:

P = j.oQ V12 + losses

200 à 300 hp.

This amount is rather low. By narrowing the slit s, the

increase of the lift compared to the open water rudder

is:

ACL :: C,

:: Vj :: sF

and the power varies as:

P:: V

::

5

Comparison of test results with theory

The open water test results with zero degrees flap angle

and zero quantity jet were compared to results

ac-cording to Prandtl's lifting line theory. The results were

very satisfactory. It was also possible to make a check

on the effect of the jet. The research on the effect of

the jet flap in the aircraft industry has shown that the

lift increment is proportional to the square root of the

momentum coefficient C,1. It also appears that the lift

increment is proportional to the sine of the angle of

deflection of the jet sheet.

Therefore the lift increment due to the jet can be

expressed as:

LCL = K./C,1 Sin/5F

in which K = proportionality coefficient.

This represents the difference between the lift

coef-ficient for the rudder at a fixed value of ÖR and 5F' with

and without the jet. The mean value of Kfor the tested

rudder was 2.5. This line, and data points, can be seen

on diagram 8 (see Appendix II). Windtunnel results

on a similar configuration taken from literature

in-dicates K = 5.4 for an infinite span wing. If this value

is corrected for the losses i.e.: finite length, the constant

K becomes:

(dcL'\

K

4\dôR

)finhte

= 5.4

= 2.37

(I)

(

1+2/A

dCL'\ d5 )infínii

where .

= the aspect ratio h/I.

It can be seen that at least for this configuration of

jet flap the increment of lift due to the jet is similar

between air and water.

Example

A single numerical example is presented in order to

illustrate the inherent advantages of the high lift rudder.

An important characteristic of the manoeuvrability of

a ship is its turning diameter. One can calculate the

turning diameter for model 2118 in the following

manner. For example:

= 7.094 m

= 0.49 rn/sec

= 30°

From diagram 9 (see appendix il) the rate of change of

heading (r) is obtained for both the normal rudder and

the high lift rudder having a flap angle 6F of 40° and

a water jet quantity of 0.032 m3/min.

12 Flap angle F Jet quantity Q Change of heading r

Lr/

D/Lp?,

Normal rudder High lilt rudder Ø0 o m3/min 1.45 degr./sec 21.0 4.64 40 0.032 m3/min 1.82 degr./sec 26.3 2.90

The turning diameter/length ratio D/L

is obtained

from diagram Il (see appendix II) [2].

A.

For the model 2118 this represents turning diameters

of 32.9 meters and 20.6 meters respectively. 1f these

values can be scaled up by conventional methods using

a scale ratio of 39.5, the following is obtained.

Particulars of the ship (full scale):

= 280m

Vapp

3.08 rn/sec (6 knots)

= 30

Normal rudder High lilt rudder

These expanded figures must be used with extreme care.

Scale-effect studies were outside the scope of the present

investigation. It has been noted, however, that

separa-tion on the rudder surface is highly dependent on

Reynolds number. Principally it is quite possible that

the effects of the high lift rudder if applied to a

full-scale ship alter greatly. On the other hand recent studies

indicate that separation on the rudder surface itself has

little effect upon the turning characteristics of a ship.

In this case the above full scale predictions would be

realistic. In view of the present confusion with respect

to scale effects and separation, one is advised to use

the model data presented here only in a qualitative

sense.

6 Conclusions

From the above research certain general conclusions

can be drawn. These conclusions pertain to the model

as no attempt was made to derive a method, or verify

established methods, of extrapolating the results to

full scale.

Open water tests

The coefficient of lift varies sinusoidally as the flap

angle 5. increases.

The coefficient of lift varies approximately linearly

as the quantity of water jet increases.

The coefficient of drag is not greatly dependent on

the quantity of water jet.

The torque on the rudder stock increases with

in-creasing flap angle and/or inin-creasing water jet.

The angle of stall of the rudder appeared to he

un-affected by either the flap angle or the water jet.

The increase in lift as a function of the momentum

coefficient agreed very well with theoretical and

experimental results of similar configurations

oper-ating in air.

B. 7víanoeu t'ring tests

I.

The turning diameter decreases with increased

water jet quantity.

The turning diameter decreases with increased flap

angle.

The gain in turning ability due to the jet flap is

greatest at small rudder angles.

The turning diameter of the model with a rudder

angle of 30° can be decreased by 37.5% at a scale

speed of 6 knots by employing a fluid flap rudder.

References

DURAND,W. F., Aerodynamic Theory, vol. II, Springer 1935.

SHEBA, H., First Symposium on Ship Manoeuvrability

D.T.M.B., 1960.

Flap angle ' O 400

Jet quantity Q o m0/hour 12,600 m3/hour

APPENDIX I.

Example calculation

20.40x iO

C1=

=1.72

-x1O0x1.892x42Tx9.22

An example calculation, illustrating the method and

Vte = VA1+CT = 3.12 rn/sec

approximations used to determine the jet quantity for

both the ship and model at a ship speed of 6 knots.

CTfor the model

Summary

of

data

Scale ratio

= 39.5

Ship speed

= 6 knots = 3.08 rn/sec

Pump capacity

= 12,600 m3/h = 3.5 ms/sec

Model

Rudder height

= 235.5 mm

Speed

=

0.49 rn/sec

Prop. diameter

= 232.73 mm

Blades

=

4

Pitch at 0.7R

= 170.77mm

Expanded blade

Area ratio

=

0.624

Wake fraction /,

=

0.387

I.

The water velocity at the screw disk of the ship

VA = V(l-/i)

= 3.08(1 -0.387) = 1.89 rn/sec

The water velocity in the race but far from the screw

disk (i.e. trailing edge of rudder)

V = V,/1+C

CT is a thrust or load coefficient of the propeller,

it is defined as:

CT

T

-4 VirD

This coefficient must be calculated by two distinct

methods for the ship and for the model.

CTfor the ship

The thrust used in the above formula must correspond

to turbulent flow over the ship. This was obtained by

extrapolating the resistance curve of the model down

to the equivalent of 6 knots. The extrapolation was

taken from model data equivalent to 14 knots where

the flow ovet the model was also turbulent. The

resistance of the ship at 6 knots is approximately 17.35

tons. Using a thrust deduction of 0.15 the required

propeller thrust T is

During the spiral tests the flow over the model was

partially laminar due to the very low Reynolds

num-bers. This caused an increased resistance and a

con-sequent overloading of the propeller. By means of the

RPM, which was recorded during the tests, and the

open water curves for the propeller, the CT values for

the model can be calculated:

RPM = 250: n

250/

= 4.17

VA = V(l -/í) = 0.49(1-0.387) = 0.30 rn/sec

From the B 4.70 screw series diagram, using the

ad-vance ratio

A = -

=

0.30

= 0.3!

nD 4.17 xO.2327

we obtain a KT value of

0.21.

KT is related to C as

fol lows T T D2,i2

CT =

=

= K

+QVA2*7rD2 QD4n2 -t VA2

in which K-, = T/p,D4n2.

Therefore

CT = 5.5

and

= 0.301+ 5.55 = 0.77 rn/sec

Ship jet velocity

Q = 3.5 m3/sec

Slit width of jet on one side of flap = s

s =0.0l98m

h =9.3m

= Q/h.2s = 9.5 rn/sec

Relative velocity ratio =

= 3.05

3.1 Model jet velocity

Relative velocity ratio = 3.05 = V1/0.77

V = 2.35 rn/sec

Q = V1h2s=0.325m/min

In table IV (page 11) the results of the calculations are

17.35/(l -0.15) = 20.40 tons

summarized.

U.S 0.2 o 1.2 04 0.2 O 0 5° 100 15° 200 25° 30° RUDDER ANGLE 6

RUDDER ANGLE &R

Diagraiìì

.

Lift and drag curves of the rudder without water jet at various flap angles.

Diagram 2.

Pitching moment coefficient of the rudder without water jet as a function of rudder angle at various flap angles.

0= YPV2AR WATER ]ET=0.0rT/mjn FLAP ANGLE

-

₃₀ 5°

4

-Í

7 _____L_Ç M FLAP ANGLE

viA

CM r

Yí'v¼.

WATER JET=0.0/min

9r,

4

5° 100 15° 20°

j3

CL WATER J E T

0 0m/mi FLAP ANGL

-___

Ir

O 50 100 15° 20° 25° 300 RUDDER ANGLE CR 06 CD 0.4 08 CL 0.5 0.2 0.1 8 0.1 6 0.1 L 0.12 CM 0.1 0.08 0.06 0.01. 0.02 o -0.02

-Ol.

-0.06 -0.08 - 0.1 t-n

2

X

M eD 300 15° _0° o o

22 2.0 18 1.6 _{0.8 0.6 0,4}

0.2 0

ADVANCE VELOCITY

05 rn/SIC

Diagram 3.

Influence of deflection of flap and quantity of water jet on the lift coefficient

Diagrani 4.

Influence of deflection of flap and quantity of water jet on the drag coef- ficient as a function of the rudder angle.

as a function of the rudder angle.

F 0.5

.

0.1 O -0.1 -0.2 -0.3. -0.4 ADVANCE VELOCITY O.S rn/sec NGLE

JET ri, i ri miri min

FLAP ANGLE

}

FLAP WATER JET 0.0 mmjn

J /

/

0D73 0.127 /min 1mm

/

/

//

/

_/

/4

,,, /

/

/

/

_/

'WATER 0.0 0073m

/

_/

/ _/ 0,127

/

_/

/ /

/ /

/

/

/ /

WATER 0,1 JET _27m/.

_II

FLAP =30° ANGLE 0.0

/

N

/

/

_/

/

/

_/

FLAP

_00

ANI3LE S

/

/

_/

WATER JET O0,0.O73;0.127m,

/

//

_/

/

_/

/

_/

o 100 15° 20° 250 30° RUDDER ANGLE SR o 5° 10° 15° 20° 250 30° 35 o RUDDER ANGLE R 1.2 C L 1.0 0.3 Cr, 02

0.1. 0.3 0.2 01 o _-0.1 -0.2 _-03

ADVANCE VELOCITY =O.Srn/sec

250

centre of effort as a function of the rudder angle.

R JET min mi min rn/rn n o 30 0.6 0.1. 0.2 WATER JET 0.245 m/min 0.167

All4

0.081. /min O ADVANCE VELOCITY 2 rn/sec RUDDER ANGLE 10° 15° 30° FLAP ANGLE <SF 45° Diagram 5.

Influence of deflection of flap and quantity of water jet on the

loLIIRn

ol he

Diagram 6.

Influence of angle of flap deflection on the lift coefficient at

ariotis waler

jet quantities (at constant angle of incidence).

WATER 0.127 0.073rn/mj JET m3/rn i n /min

1_

FLAP ANGLESF 0

//

/

0.127

/

/

t.

-1.4 1.2 1.0 LAP ANGLE = 30° 0.8 CL O 50 100 15° 20° RUDDER ANGLE S

-F CD 0,3 0.2 0.1 o - 0.1 0.3 0,2 0.1 O - Ql ADVANCE VELOCITY - 2m/c

RUDDER ANGLE =10° ADVANCE VELOCITY

2 rn/sec RUDDER ANGLE-10° 5° o WATER JET 0.21.5 m/mjn 0.167 0.084 m3/rnn

00 rnj

WATER JET 0245 m'/mjn 0.167 m/jfl 0.081. m/1fl 0.0 m% 20 18 1.6 iL ACL SIfl9 1,2 1.0 _{0.8 0.6 0,4 0.2} O 03 0./. 0,5 V QrnVj

YfV2ht

EGUATION of ACL2.5\f)J LINE Sifl O

/

o s

(/7

/

_/

_/

£ e4

/+

X

Ad

Ar

FLAP ANGLE

pPr.

FLAP ANGLE 30° 4 0.1 02 0.6 0,7 0.8 0.9

Diagram 7. The variation of drag coefficient and of the location of the centre of effort

with the angle of flap deflection at various water jet quantities (at constant angle of incidence).

Diagram 8. The increase of lift due to the essential parameters, the momentum coefficient

C, and the jet direction

18 'J

ï

_10° u-o 1.5 2.0

Diagram 9. Rate of change of heading as a function of rudder angle for various flap angles and jet quantities (velocity of approach 0.49 m/sec).

Note: Flap angle always in same direction as rudder angle.

APPROACH VELOCITY =0.1.9 rn/sec MODEL 2118

IFLAP1.O°

IJET =

O.OLLm _min

1.5 FL JETS.O1./.rr P F

'

in

=1.O0JET=O.O3jn

A LA P 1.00 JET

00m!mrn

-LAP'

0° JE T oFmh/m _n 1.0

/

V

OES

/

z

-5e 50 100 15° STARBOARD RUDDER ANGLE 20° 25° 300 350

o APPROACH VELOCITY 0253m1 MODEL 2118 ¡Sec 40 30 10 O

Diagram Il. Emperical relation between the turning diameter-ship length ratio and the

turning velocity-approach velocity ratio.

,.ÇFLAPF 40

JET 0.032m/mjn

FLAP=L0°

0.021in

o FLAPS1=0 JET -0.0 rn/mm I I I I U 2 s 6 7 8 D/L 0° 10° 20° RUDDER ANGLE Diagram IO.

Rate of change of heading as a function of rudder angle for various flap angles and jet quantities (velocity of approach 0.253 rn/see).

1.2 10 _0.9 0.8 0.7 u 0.6 ID w o

z

-

o

z

o 4 DA IL o w o

z

0.3 4 X L) o 0.2 w F-

4

0.1

L.r

V pp 20

PUBLCAT[ONS OF THE NETHERLANDS SHIP RESEARCH CENTRE TNO

PUBLISHED AFTER 1963 (LIST OF EARLIER PUBLICATIONS AVAILABLE ON REQUEST)

PRICE PER COPY DFL.

IO,-M engineering department S = shipbuilding department C corrosion and antifouling department

Reports

57 M Determination of the dynamic properties and propeller excited vibrations of a special ship stem arrangement. R. Wereldsma, 1964.

58 S Numerical calculation of vertical hull vibrations of ships by discretizing the vibration system, J. de Vries, 1964.

59 M ControlLable pitch propellers, their suitability and economy for large sea-going ships propelled by conventional, directly coupled engines. C. Kapsenberg. 1964.

60 S Natural frequencies of free vertical ship vibrations. C. B.

Vreug-denhil, 1964.

61 S The distribution of the hydrodynamic forces on a heaving and pitching shipmodel in still water. J. Gerritsma and W.

Beuke]-man, 1964.

62 C The mode of action of anti-fouling paints: Interaction between anti-fouling paints and sea water. A. M. van Londen. 1964. 63 M Corrosion in exhaust driven turbochargers on marine diesel

engines usingheavy fuels. R. W. Stuart Mitchelland V. A. Ogale, 1965.

64 C Barnacle fouling on aged anti-fouling paints; a suvey of pertinent literature and some recent observations. P. de Wolf, 1964. 65 S The lateral damping and added mass ofa horizontally oscillating

shipmodel. G. van Leeuwen, 1964.

66 S investigations into the strength of ships' derricks. Part I. F. X.

P. Soejadi, 1965.

67 S Heat-transfer in cargotanks of a 50,000 DWT tanker. D. J. van der Heeden and L. L. Mulder, 1965.

68 M Guide to the application of method for calculation of cylinder liner temperatures in diesel engines. H. W. van Ti len, 1965. 69 M Stress measurements on a propeller model for a 42,000 DWT

tanker. R. Wereldsma, 1965.

70 M Experiments on vibrating propeller models. R. Wereldsma, 1965. 71 S Research on bulbous bow ships. Part II. A. Still water perfor-mance of a 24,000 DWT bulkcarrier with a large bulbous bow. W. P. A. van Lammeren and J. J. Muntjewerf, 1965.

72 S Research on bulbous bow ships. Part II. B. Behaviour of a 24,000 DWT hulkcarrier with a large bulbous bow in a seaway. W. P. A. van Lammeren and F. V. A. Pangalila, 1965.

73 S Stress and strain distribution in a vertically corrugated bulkhead. l-l. E. Jaeger and P. A. van Katwijk. 1965.

74 S Research on bulbous bow ships. Part I. A. Still water investiga-tions into bulbous bow forms for a fast cargo liner. W. P. A. van Lammeren and R. Wahab, 1965.

75 S Hull vibrations of the cargo-passenger motor ship "Oranje Nassau", W. van Horssen, 1965.

76 S Research on bulbous bow ships. Parti. B. The behaviour of a fast cargo liner with a conventional and with a bulbous bow in a sea-way. R. Wahab. 1965.

77 M Comparative shipboard measurements of surface temperatures and surface corrosion in air cooled and water cooled turbine outlet casings of exhaust driven marine diesel engine turbo-chargers. R. W. Stuart Mitchell and V. A. Ogale, 1965.

78 M Stern tube vibration measurements of a cargo ship with special afterbody. R. Wereldsma, 1965.

79 C The pre-treatment of ship plates: A comparative investigation

on some pre-treatment methods in use in the shipbuilding

industry. A. M. van Londen, 1965.

() C The pre-treatment of ship plates: A practical investigation into the influence of different working procedures in over-coating zinc rich epoxy-resin based pre-construction primers. A. M. van Londen and W. Molder, 1965.

81 5 The performance of U-tanks as a passive anti-rolling device.

C. Stigter, 1966.

82 S Low-cycle fatigue of steel structures. J. J. W. Nibbering and J. van Lint, 1966.

83 S Roll damping by free surface tanks. J. J. van den Bosch and J. H. Vugts, 1966.

84S Behaviour of a ship in a seaway. J. Gerritsma, 1966.

85 S Brittle fracture of full scale structures damaged by fatigue. J. J. W. Nibbering, J. van Lint and R. T. van Leeuwen, 1966. 86 M Theoretical evaluation of heat transfer in dry cargo ship's tanks

using thermal oil as a heat transfer medium. D. J. van der

Heeden, 1966.

87 S Model experiments on sound transmission from engineroom to accommodation in motorships. J. H. Janssen, 1966.

88 5 Pitch and heave with fixed and controlled bow fins. J. H. Vugts, 1966.

89 S Estimation of the natural frequencies of a ship's double bottom by means of a sandwich theory. S. Hylarides, 1967.

90 S Computation of pitch and heave motions for arbitrary ship forms. W. E. Smith, 1967.

91 M Corrosion in exhaust driven turbochargers on marine diesel engines using heavy fuels. R. W. Stuart Mitchell, A. J. M. S. van Montfoort and V. A. Ogale, 1967.

92 M Residual fuel treatment on board ship. Part II. Comparative cylinder wear measurements on a laboratory diesel engine using filtered or centrifuged residual fuel. A. de Mooy, M. Verwoest and G. G. van der Meulen, 1967.

93 C Cost relations of the treatments of ship hulls and the fuel con-sumption ofships. H. J. Lageveen-van Kuijk, 1967.

94 C Optimum conditions for blast cleaning of steel plate. J.

Rem-melts, 1967.

95 M Residual fuel treatment on board ship. Part I. The effect of cen-trifuging, filtering and homogenizing on the unsolubles in residual fuel. M. Verwoest and F. J. Colon, 1967.

96 S Analysis of the modified strip theory for the calculation of ship motions and wave bending moments. J. Gerritsma and W.

Beu-kelman, 1967.

97 S On the efficacy of two different roll-damping tanks. J. Bootsma and J. J. van den Bosch, 1967.

98 S Equation of motion coefficients for a pitching and heaving des-troyer model. W. E. Smith, 1967.

99 S The manoeuvrability of ships on a straight course. J. P. Hooft, 1967.

100 S Amidships forces and moments on a CB = 0.80 "Series 60' model in waves from various directions. R. Wahab, 1967. 101 C Optimum conditions for blast cleaning of steel plate. Conclusion.

J. Remmelts, 1967.

102 M The axial stiffness of marine diesel engine crankshafts. Part 1. Comparison between the results of full scale measurements and those of calculations according to published formulae. N. J.

Visser, 1967.

103 M The axial stiffness of marine diesel engine crankshafts. Part II. Theory and results of scale model measurements and comparison with published formulae. C. A. M. van der Linden, 1967. 104 M Marine diesel engine exhaust noise. Part I. A mathematical model.

J. H. Janssen, 1967.

105 M Marine diesel engine exhaust noise. Part II. Scale models of exhaust systems. J. Buiten and J. H. Janssen, 1968.

106 M Marine diesel engine exhaust noise. Part III. Exhaust sound criteria for bridge wings. J. H. Janssen en J. Buiten, 1967.

107 S Ship vibration analysis by finite element technique. Part I.

General review and application to simple structures, statically loaded. S. Hylarides, 1967.

108 M Marine refrigeration engineering. Part I. Testing of a

decentrai-ised refrigerating installation. J. A. Knobbout and R. W. J.

Kouffeld, 1967.

109 S A comparative study on four different passive roll damping tanks. Part 1. J. H. Vugts, 1968.

110 S Strain, stress and flexure of two corrugated and one plane bulk-head subjected to a lateral, distributed load. H. E. Jaeger and P. A. van Katwijk, 1968.

li I M Experimental evaluation of heat transfer in a dry-cargo ships' tank, using thermal oil as a heat transfer medium. D. J. van der

Heeden, 1968.

112 S The hydrodynamic coefficients for swaying, heaving and rolling cylinders in a free surface. J. H. Vugts, 1968.

113 M Marine refrigeration engineering. Part II. Some results of testing a decentralised marine refrigerating unit with R 502. J. A.

Knob-bout and C. B. Colenbrander, 1968.

114 S The steering of a ship during the stopping manoeuvre. J. P. Hooft, 1969.