Hydromechanic characteristics of a shipmodel of the Mariner type

ARCHIEF

Lab.

v.

11TH INTERNATIONAL TOWING TANK CONFERENCE

Subject - Manoeuvrabilit

Hydrodyriaiflic Characteristics of a Shipmodel

of the "Mariner" type by

G.A. Pirsoff

The paper presents the results of the "Mariner" type model

tests. The tests have been carried out at the A.N.Kryloff Ship

Model Basin, U.S.S.R. The determination of hydrodynamic

charac-teristics for a ship of the "Mariner" type, which were required

for the design of steering, has been made as a result of these

teats. Apart from the above mentioned characteristics, such

qualities have been exmiined as free circulation of the ship and standard "Zig-Zag" manoeuvre.

The work has been carried oui within the framework of a

general program of shipmodel steering correlative trials, which.

program had been developed by the International Towing Taxk

Con-ference - Manoeuvrability Coimwtttee..

1. Symbols and Co-ordinate Axes

The following symbols are used in the paper:

Water density . 1

Speed of advance relative to water . . . .

Drift angle Trim angle Rudder angle

Latera1force...0.

7

I I I

vecnrnscne rosco

Writ.teecfftribution

Yaw moment . . -

My

Non-dimensional force coefficient . C

Same for the moment I"ILJ I7

Drift angle non-4imensional derivative .8

of force (moment)

(my )

Same for rudder angle

C/

(/77/)

Radius of curvature for a model centre

of buoyancy path R

Angular velocity of rotation CO

Non-dimensional angular velocity . . .

=c)

--Symbol of increment for coefficients of

h.ydrodynamic reaction due tO rotation0 .

Non-dimèñsional rotational derivative _4,

₀

_C(amy)

of force (moment) C (i77g )= .

Non-dimensional diameter of steady

circulation _L.

Speed in circulation

Aiflplitude of angular velocity

Circular frequency of rudder shifting.

5

Non-dimensional frequency of rudder

_-

_L

shifting .

5

Co-ordinate system of )yE axes is rectangular on the left

and connected with a ship. Origin of co-ordinates is in the

centre of gravity; axis X is positive afore,piane X is parallel

to Water-plane. 2. Model Tests

Three models were tested.

Model No.1 isa model with duplicated underwater part of ship

hydrodynamic characteristics of advance in a wind

tunnel.

Model No.2 is a model with duplicated underwater part of ship

body, which is intended for the determination of

rotational hydrodynamic characteristics under

condi-tion of full submergence.

Model No.3 is a floating self-propelled shipmodel with a

free-board; it is intended for the determination of

hydro-dynamic characteristics in the presence of free

stir-face and with the propeller running, and also for

direct simulation of ship's manoeuvres.

These models were manufactured according to the body-plan,

mentioned in the work [].]. Models Nos ]. and 2 were in conformity

with the even keel position of the "Mariner" type ship; model

No.3 was tested in both positions, i.e. on even keel and with

trim by the stern. The trim was in conformity with the position

of the "Compass Island",one of the "Mariner" type ships subjected

to inanoeuvring trials.

Hereinafter the position of a model on even keel will be

referred to as position No.1 and the position of a model with, trim by the stern as position No2.

The principal data on models tested in position No.1 are

swi2xnarized in Table No.1; the data on model No.3 tested in

position No.? are shown in Table No.2. All the models have been

fitted with bilge keels whose size was in conformity with

33.6

in x 0.457 in of the full-scale keel.

Table 1 Principal Features of Models Tested in Even

Keel Position Item: No.: Description : Model : Model : No.1 No.2 Model :Pull-acal No.3 : ship 1 Scale _{1:52.6 1:79 1:79} -2 Material . . . . Foam plastic' Paraffine Wood -3 Length b.p., m . 3.045 2.030 2.030 160.9 4 Breadth, in . . . . 0.438 0.293 0.293 23.17 5 Draught, in . . . .

0.156

0.104

0.104

_8.?3 6 Displacement, m. _{0.1269 0.0376}

_0.0376

_18,674 7 Centre of gravity abscissa, counting --0.0432 --0.0288 -0.0288 -2.29

Since model NO.3 Was manufactured as a self-propelled version, Table 3 shows its propeller elements,

Table 3 Principal Features of the Propeller for Model No.3

Table 2 Principal Features of Model No.3 Tested with Trim

by the Stern

3. Hy-drodynamic Characteristics of Advance for Submerged Part of Ship Body ,Determined withOut Consideration of the Effect of Free Surface

This group of characteristics has been, obtained from model No.]. tests carried out in the wind tunnel. The experiments were performed under the following cond.ition8:

'em

_{Description Model}

1 Dieplacement, 0.034

16,800

2 Draught fore, m .. 0.087

6.858

3 Draught aft, rn . .. . . . 0.102

8.077

4

Centre of gravity abscissa,

counting from,

rn

. .

.

-00456

-3.70

Ih!

_Description - Model

Pu17cale

1 Number of blades 4 . 4 2 Diameter, m . 0.085 6.706 3 Pitch ratio on 0.7R . . . 0.090 1.038

4 Blade area ratio , . . . .

0.58

0.565

air flow velocity _{70 in/eec.,}

air temperature 200C,

Reynolds number

1 5°10.

Varied during these experiments were:

drift angle (angle of incidence) . . . within 0-20 deg.,

rudder angle . . . within 0-40 deg.

The results of advance characteristics determ1ntjon are in the form of plots shown in Pigs 1-4.

Initial values (with _{j3==5=O ) for the drift angle}

angle derivatives of bydrodynainic coefficients are

Table 4.

I

Table 4 Initial Values for Advance Derivatives of Hydrodynamic

Coefficients (Model No.1)

Derivative

model speed

5-1,020 ₅₃₂

1 147 -67

4. _{ydrodynarnic Characteristics of Advance for Submerged}

Part of Ship Body Determined in the Presence _{of free}

Surface

This group of characteristics has been obtained

from model

No.3 tests carried out in a straight-lined tank. _{The experiments}

have been performed under the following conditions:.

C(/o'

0.87 rn/sec. (corresponding to

15 knots for full-scale ship);

water temperature 20 deg. S

Proude number

_019.

Varied during these experiments were:

drift angle . . . within the range of 0-15 deg.,

Value

I

presented

or rudder

rudder angle within the range of °-±35 deg.,.

positions of the model . Nos ]. and 2,

method of model drive . resistance trials Of the model

with no

propeller and with

propeller running.

In trials of the shipmodel with a propeller- running, Ihé

propeller number of revolutions per minute was in conformity

with a straight-line running of the model under self-propulsion

condition (with no correction for friction scale effect).Resu].ts of trials are represented in Figs 514.

Initial values (with

O)

for the drift angle or rud4er

angle derivatives of hydrody7rnmic coefficients are

given in

Table 5.

Table 5 Initial Values for Advance Derivatives of Hydrodynamic Coefficients (self-propelled and non-propelled versions

of model No.3)

Pigs 7 and 11 èhOw additionally plotted curves of the

coefficient for that part of the lateral force which arises

directly on the rudder plate at a corresponding rudder angle

Measurements of the lateral force on the rudder have been

taken by means of the instrumentation described in para 8. 5. Rotational Hydrodynainic Characteristics Determined

without Consideration of Pree Surface Effect

This group Of characteritice has been obtained from model

-

6-.

C5 /0

1

8 51

mM /0

c ic

/77g /0

6,;

Position No.1 of the

modeiwith propeller 1,460 498 252 142

Same without propeller 1,350 570 126 5].

Position No.2 of the

model with propeller 1,490 350 269 126

No.2 tests made on therotating installation in a model tank0 The tests have been carried out under the following conditions:

towing tank dimensions 20x35x3.5 in;

water temperature . . . 20°C.

Direction of rotation of rotating

installation arm counter clockwise

Velocity of the model centre

of gravity 1.2 rn/sec.

Immersion of the model waterline 1.2 in.

Varied during these teats were:

radius of curvature for the model

centre of gravity path 3.5,

4.5, 6.0

and 8.0 in;

model drift angle within 0-18 deg.

During the tests the rudder of the model was held in its centre

line.

Direct results of the tests for the deterin.ination of the

rotational characteristics are plotted in Pigs

₁₅

and 16 as

hydrodynamic coefficients _C and 1179 versus non-dimensional

angular velocity of model rotation U at different values of the drift angle fi. Dots plotted for these relationships with

agree with the model advance running and are borrowed from the

materials of model No.]. tests which were carried out in the wifld

tunnel(see para

3).

The linear character of the relationships maintained up _tow

= 0.4+0.5 makes it possible to determine derivatives

cf

and /714!

which are constant in the above range. These values are plotte&

in Pig. 20 as a function of drift angle .Table 5 gives their values

corresponding to the particular case of 0.

Table 6

Initial Values for Rotational Derivatives of Hydrodynamic

Coefficient

(Model No.2,

'O,5,fi=O )

F Derivative Value

-

7-I"',

330

,77;/Q$

-255

It is to remember that, owing to the peculiarity of

deter-mining rotational deriatives by means of rotating plant, their

value8 involve

the effect of added mass.

6. Rotational H.ydrodyrum1c Characteristics Determined in the Presence of Free Surface This group of characteristics has

No.3. tests carried out on the rotating

in pars

_5.

radius of

curvature for the

model centre of gravity path

model

drift

angle

positions of the model method of driving

Results of the tests for the determination of rotational

characteristics are represented in Figs 17-19 and 21-29.

Like in the previous case, the linear character of the

relationships, expressed as a function of W, is maintained up to

ct) O.4 + 0.5 and makes it possible to determine the initial

values of derivatives C and f77. Table 7 gives these values

for the case of 0.

Table 7 Initial Values for Rotational Derivatives of Hydrodynamic

Coefficieüts (model No.3)

Position No.]. of the model

with propeller 80

Position No.1 of the model

without propeller . . . .

175

PosItion No.2 ofthe model

with propeller .

-ll5

Position No.2 of the model

without propeller . . . _.

195

3.5, 4.5,

6.0 and 8.0 rn;

over the

range

0-18 deg.;

Nosland 2;

towing carriage, no propeller; self-propulsion,

with propeller

rnnMng.

been obtained from model

installation as mentiâne4

,n;.ics

-350 -310 -290 -265 V8ried during these tests were:

Determination of Steady Circulation Elements by Means of Self-Propelled Model Tests

The tests were carried out on model No.3 in positions Nos 1

and 2. The model has been manufactured as a radio-controlled,

completely self-contained version. Model running Was registered

by taking photos from above. Angular velocity of turning model

was also registered during trials.

These tests were carried out in the same tank as those of

model No.2 on the rotating installation. Varied during these

tests were:

within 0-40 deg., rudder angle

both port and. starboard;

speed before the start of

manoeuvre Within 0.6-1.5 rn/eec.

Photographs obtained permitted to determine the following: the path of the model centre of gravity movement; model speed.

Results of registering the model movement elements in a

steady period @ circulation are plotted in Pigs 30-33. Results

of mode?. angular velocity measurements are shown as diagram

in Pig.34. A zone adjoining the co-ordinate origin is

plotted in this diagram as a result of the experiment..The latter permits to register the process of changing the angular veloôity of the model which runs with a ahiftéd rudder, after some initial

angular velocity is attained. Rudder angles at which the model

after the said disturbance may approach circulation refer to the range of instable model movement. This circulation may either be

in agrement with or in opposition to the sign of rudder angle.

The limiting values of these angles,marked on a diagram by 'dotted

lines (critical values of rudder angles), can be dèteimined by

way of repeating the described experiment with several values of the rudder angle.

Determination of Stead Circulation Elements

in Self-Propelled Model Tests under the Rotating Installation

The procedure of these tests had been reported to ITTC-63.

It is based onautomatised matching of rudder angle and propeller

speed so that the conditions of the mode]. running under the

10--at a

predetermined radis of grn and, a predetermined

running speed in

circu].ation-During these tests were determined: rudder angle;

drift angle;

normal component of force acting upon the model rudder.

Because of some autooscillatione inherent to the automatiô

control system of a model rudder, the values to be measured are

registered continuously and averaged in the processing of data.

Model

_No.3

was tested in positions Nos 1 and 2. Results of

the tests are illustrated in Pig. 35.

9. Evaluation of Capability to Steer a Ship by Means of Direct Siilation. of.. "Zig-Zag" Manoeuvre with a Model

These tests were carried outon model

No.3

in

positions

Nos 1 and 2. The self-contained variant Of the model was tested,

but, unlike the tests in circulation (see pare 7), instead of

radio-control the model was fitted with a device which ensured

trapeziform rudder shifting with predetermined amplitude and

frequency. The time of rudder shifting was maintained constant

and correspon4ed to rudder shifting time of a full-scale ship,.

It was equal to 30 eec for full rudder (2.6 deg./sec).During the

tests, measurements were taken of the model angular velocity

which, together with a check record of rudder shifting, was

registered by means of a loop oscillograph.

The tests have been carried out under the following

condi-tions:

model speed Within 0.6-1.3 Wsec;

amplitude of rudder shifting within 4-20 deg.;

frequency of rudder shifting within

0.09-0.60

C.P. .

Results of these tests are plotted in Figs 36-37,

Reference

1. V.LRueso, E.K.Sullivan. "De8i of the Mariner-Type

Q6 0 10 0 0,5 0

Pig.2. Monent of yaw verona drift agle at zero rudder angle. ondttiona are

u1ar to those in Pig.1.

I I I 5 10

11-10 _{15 ft0} Pig.l. verona angle. nodal model Coefficient drift Cavitation vithont on oven angle opel1er; keel. of tunnel; lateral at core position force rudder duplicated of

-I.

C1o' Pig.,. verona angle. in Pig.l.. rudder Conditions Coefficient angle are of lateral at ainilar zero drift to those force

,/'

-/

. I 10

15f

cztos 40 40 a2 0.1

- q3

.t

-.-10 C fQ3 4,0 3,0

12---WIih Pig.5. Coefficient

vereul drift angi

angle. Straight-i

floating model witb 11th propeller war model on even keel.

,,

. -. 20 - *0 &°

-

Pig. t wero aiml.lar 4. Moment dzift to theee of yaw angle. in versue Fig.l. Conditiono rudder angle are - 1,0 2,0. 3,0 40

-13-/

/

/

/

/

//

LWihpwp.

/

/

/

/

-0 ₅ 10

verona drift anglo Conditicne are Pig 5

Pig;6.-Moment of yaw

at sore rudder angle. eiidlaw to thoeein /."

i3Ocz1c

T

-WILh .w..,

-

_...A4llld

--.

-0-pr

Ad

T

-Pig.7. verona - angle. P1.g.5. of rudder in lateral the Coefficient coadittona rudder coefficient force which plate. Additionally of eagle at are elder for amoco lateral force sero drift to thoae are plotted that part of directly on

--

- ..e-curvee

,

3 4,, 1,0 2,0 -40

-14-cz

Pig.9. Coefficient of lateral force verane drift angle at zero rudder angle. Streit-11ned towing tank;

floating model with no propeller and

with propell.r working; model poaition

with trim by the atern. at zero cimilar

1---I Pig.8.Mcmeflt drift to thoau of yaw angle. in verau I COnditiona rudder angle

r

are I

'

-\.

\

I 20 3U

20

Pig.1l. Coefficient of lateral force

Verona rudder angle at sara drift

angle. Conditions ore similar to those in Pig.9. Additionally ore plotted

corvee of coefficient for that pert of

lateral force which ariaee dimectly on

the rudder plate.

-15-1.J mio3 q5 -wiih pwp_.

7/

7.

,,

10 5 0 5 (0 ,80

Pig. 10. Mnt of y coefficient Verona

drift angle at sore rudder angle.

Conditions era cihilar to those in

--_

- _{Pig.12.?Lomont of yaw coefficient versue}

nid.der angle t Zeo drift angle Conditon8 are sirildr to those in Pig 9 - -WLth pzop.

---- -. ---. ---Q4 n.c- - --- --- -Fig.1-3. versua equal lined propeller with trin Coefficient rudder to zero towing tanh; working; by the o angle and ±10 etern. floating poaitionof lateral at drift deg model force angle Straiit-with nodel -CIO

-- - - 2,5 --- -- ----ft=0' - -- 0 --

to---2

1v

ft.

-.

a_

IItrit

Oilir:

rudder to zero elrnilar Fig.14.Moment angle and to those of yaw at drift +10 dog. in Pig.13. coefficient angle Conditions v6rone equal. are _ft in _______ -Cio3_{Z Pig.15.} verona (relative ferent rotating cated of model I drift model on Coefficient non-dimensional curvature installation; I angles. without even keel. of lateral, force angular velocity of path) at dif-Model tank; imeez'eed thipli-propeller;positiOfl

--

- - -- -- --

--ft

- __.,_- .-.'

TT>1

-

- --42 - I - e -

-q5 - --- -. i40 90 8/3 40 3.0 2, 1. 0 0 0 0 0 0°

q5 0 q5.

-18-45

I___

Pig.16.Moiient nón-dienaiona1 different

si1ar to

drift o yaw thoBe in angu'ar angles. Pig. 15. coefficient ConditiOna velocity vergue at are - 0

0 510

19

(C#Czn).f03

I

-I.______

K

-

-

_-M ft:(5 C----Wiih £ I pwp..

-I

-.----__U

q4

-

-

/

.-_-.

U

,

Pig. 17. Coefficient of lateral

(component of centrifugal force

jertia inclueive) versua

non-d.iren-aioual angular velocity at different drift anglea and at rudder angle to zero. Model tank; rotating

tion; floating model with no propeller end with propeller working;

of model on even keel.

of equal inatalla-poaition - -

-4

to 0

-(0

-20

-2

0

AØ--'-I-.

A I 0

-__-&___ Ftg. 19;

:1.

WLth04fi7-O2L

-a'. w

20 -- WLth pwp.

-

02

--_Pige verona angle at different .B-19. equal nn-d.ironnional tá thOó Menent of drl.ft anglee to zero. in aw angular Pig.17. and Conditiona coefficient ve1aoit at rudder

_

-are similar -

-H

-I

-21-_50 - -j Pig.20. coefficient force of dineneioiial aw versus angle. in Pig.17. I 5 erivative inertia drift Conditions (component angular I of inclusive) angle are velocity I 10 laterml at zero aiñiilar of centrifugal and moment force non-of rudder to those I p°'

-WLLh pwp

VUU

-,.

-.______1._---.-4----' (cz+Czin)1Ot

-WLf.h pop.

-i--:

Pig.21. Coefficient of lateral force (component of centrifugal force inertia tnolusive) vereun

non-dimen-aioual angular velocity

at

different

-drift angleD and at rudder angle equal to zero. Model tank; rotating inutalla- tion; floating model with no propeller and with propeller working;

pocition

of model with trim by the atom.

of

4

1 0 2 0 -2 I

23-,T.fos

ft5°

_{WLth pwp.}

-___________

45 ag1e aimilar equal. to to thoae zero. in Coiditiona Pig.21. are m,r? - -WLthou pwp.

.-___

T---

---._---- 42

!i

₂

_{__}

45 cZ 5O --Fig. 23 .

-24

-

0_

10

V

-

..

10

V

-WLwp.A

-P' Pig. coefficient

24. Derivative of lateral force

(component of centrifugal of inertia inc].uaive ) and

non-angular velocity moment of verona angle of drift at rudder

equal to zero. ConditionE are

to thoae in Pig.21. force dimenoional angle e1.lar

,,

750 yaw

-öv-

Po7.

Pig.25.Lateral force coefficient

(corn-ponent of centrifugal force of inertia

incineive )versue non-dimeneional angular

velocity at drift ang].ee of 0,5 and 1(

25

Model tank; rotating ineta].lation; floating model with propeller working; position of model with tm by atemn.

h

,

L

5

26 -I

fl=O 1 &_Pot1

-o

I_

Ci.? 1,0 _{Pi 26,} ficient velocity 10 deg. Conditiono Pig.25. 27 an vereue at drift and at are 28 Meñt ang].ee different sinilár n-d1nenaiona1 of yaw of rudder to coat-angular 0,5 and anglea. thoao in 00 jrfl,.,o$. -

--- -

-0 -0. 0

ao

-500 -750

27-C

0

10 ₂₀

so6

_4i r,Cio5

--_____ 55O

-

- -I---- I ftqo

:i

-

-

4-Th_

Initial va.uea ?oi' derivativea force coefficiente

verona rudder angle

of 0,5 end 10 deg. eied.lar to thoce in Pig.25.

end of Pig.29. of lateral drift monent drift anglee tione are at Condi

-V 10 o 0 O68m/se,. * 4ZPO,93'se'r. x x_T.r,.lgm/seg. _Zr=f,38m/sex.

-28-II

''

1.18 pig.30. circulatiOn different Relative vmuB epeede.. model diameter rudder Model poaitiOfl angle tank; of model of eteadl at eelf-on 1. ; 93

____

1i11

A4I

Pig.3L Relative apeed in ateady circul-ation vermua relative diameter of

circulation. Conditiona are ejidlar to

theme in Fig.30.

a. 0

0laP8"4eK.

o x

x-P=,If0IseK.

-29-to Pig. oi?culation by the different propelled trim 32. Relative vereua epeeda. nodal; stern. diamOtOr rudder Model position Of angle tank; of nodal etead at ue3!-vith 098

F

h

0.72 -t 1f0

__9L

\_.. *..."o

c

00 -.

Pig.33.Re].ative speed in Btead7

circulation versuO relative diametar of circulation. Condition_s are ainilei. to those in Pig.32.

I0

fl° Pig. 35 Relative diameter of circulation

- and drift angle versus rudder angle.

tank; rotating installStiofl

ing model with propeller working.

eervomechaflisu providing such

01 of electpic motors and rudder

reacticfl of modal transferred to

ing installation to equal to wero.

50

w

Pig. 34. NomdimenaiCnal amgula

in steady circulation versuj angle.Model t;oelf-prepe1l poeltiom of model on even kee

trim by the stern; condition

running corresponding to r opeed of 15 haote. I-- .

..

-i-'OLt

-\

15 I-10 I 5 . sL

-__

_end contx that rotal C_p)iO

_

- -velocity rudder d model; and with of model al ship 50

0.2 100

Pig.36. Ratio rudder angle

of angular velocity sad

amplitudes versus

non-dimensional frequency of rudder

shift-+ ing at different speeds and amplitudes

*

+

Model tank;

of rudder angle.

eelf-4.

_{+ 4,} propelled model; position of model on

even keel. 0 IC 16 23 -+ aso 17 0 0 0 -

+

4

+

13 + 4 8 0,2 04 6 00 475 450 0 0 0 20 20 0 a G 0 0 S 0 0 a ₀ C-0 Pig rudder ing of - propelled trim dimensional 37. Ratio angle at different rudder angle. by the model; of angular amplitudes frequency stern. speeds positiOn of rudder and Model tank; velocity versus of amplitudes model and 0 0 a _-o non- shift- self-with I 0 a Li5