Hydrodynamic pressure on a ship hull in regular head waves

(1)

16 OKT. 1972

RCHJEF

ÏI1fot1eek vaiì-5bouwkunde nd e ra!dø lin sche Hogeschoc, DOCUMENATIE

: Kj8. '

D At UM:

IT) I) (ti i E N I Â TITI

Lab.

_{y. Scheepsbouw}

Technische Hog

_escoo[

Committee 2PeJftsc

April 1972, Lyngby )

/ £c,t4

Hydrodynamic Pressure on a Ship Hull in Regular Head Waves

By S. Nakamura

As a part of the research works of the 1318t Research Committee of

the Shipbuilding Research Association of Japan, model experiments obtainin

the hydrodynatnic pressure on a ship hull in regular head waves have been carried out at the Experiment Tank of Osaka University.

The experiments have been made by FRP model of the ore carrier

"KASAGISAN MARU", and the particulars of model ship are given in Table 1.

A summary of the test conditions is given in Table 2, and tie kinds of experiments are as follows

Experiment I : the model was free to pitch, heave and surge and

restrained for roll, sway and yaw in regular head waves, and amplitude of hydrodynamic pressure

was measured.

Experiment II the model was restrained for all motions in regular

head waves, and amplitude of wave induced pressure

was measured.

Experiment III : the model was forced to oscillate sinusoidally in

calm water, and amplitude of pressure by ship motion

was meaured. ( in this experiment only pure heave

was carried out and amplitude of pressure was

measured )

Pressure was measured by a semi-conductor type pressure transducer and the positions of measurements are 6hown in Fig. 1.

The experimental results of ship motions and hydrodynamic pressures

are compared with the theoretical cTidculations based upon the strip

theory and are presented in Figs. 2 - 10.

(2)

-1-Table 2. _{Test conditions}

-Item Pressure gage

location

Speed Fn

Wave length Ways height

2A(czn)

'L ¡2¼ (i) Response S.S.2 1/2, 5, 8 1/2 0.15 0.70 - 1.1+0 6.0 op.rator O = 0, 50,

800 _{C L /}

_{50 )} (2) Effect of S.S..2 1/2,

5, 8

1/2 0.0 - 1.00 6.0 ship speed = 0, ,

8o°

0.15

(3)

Longitudna]. distribution S.S. 1, 2 1/2, 5, 7 1/2, 8 1/2, 9 1/2 0.15 1,00

6.o

0 0, 50,

800

---(k) Girthwise distribution S.S.2 1/2,

5, 8

1/2 0.15 0, 20, 50, 70 0.90,L.00, 1.20,1.4.0

6.o

8o°

(5)

Effect of S.S. 2 1/2, 5,

8 1/2

0.0 1.00 2.0 - 14.0 wave heìgbt

_e

_o,

50,800 ( L / 150 - L / 21 ) Table 1. Main particulars of ship model

Ship type Ore Carrier

Length between perpendiculars 3.0000 in

Length on the waterline 3.0497 m

Breadth 0,4932 m

Draught 0.1943 in

Volume of displacement _0.2273 in3

Block coefficient 0.821+3

(3)

Sections of

odeJ

howing pressure gage locations

s.s 8 1/2

H0= 1.23kk

ç-

0.9760

!i 10°

Ii I) 1 'I

t'

I

w

roo

Midship

Iû= 1.2688

a-= 0.9975

actual form

Lewis fore

bJjc

6 =0°

200 Fig. 1.

e =Q0 _20G ₂₀₀

(4)

0.5-"û

o

Heave

R1fh

E><petírnert

o

CaJcu (ctt/o

I'ig.

2. Response amplitude operators of heave and pitch.

/O

»5

û

(5)

En =

s/. 2

_Exp1

CcLI.

bxp.

I,

=00

₀

1.û -

/

Oo_

-Q

y

o

/0

û

o

G

o

I I i

0.8

X X

¡.11

X >K

&

-S-'-S -S IS I

/.2

.1.. i I L

7

8

L

mcl

/SL)

Fig. 3. Response anp1itude operators of hydrodynamic pressure.

X 'J

H

0.8

1.0 /.2

'7-

/.'

X )<

x

iL

X X X 5Z

(6)

Os

/.û

Ô

1.0 cO

1.0.-

SO 800 O

o

Eh =

/L.1/dSJ? íf

cI.

0.9

J.4 1.0

/2

o

0.2 Exp. J

&P.

o

/',

\.

N

/

X

XN

X

/

-X

I,

.-..

\

1/

/1

//

/.û

Exp.

-X -S S--.5

¡-O

I I I

¡.2

5...

5.---S--

C) -5. '5. '5. '.5.

X

Fig.

kesponse amplitude operators of hydrodynamic pressure.

X

>.

o

¿

o

_o

¿1

/4

/.2

(7)

r

-Ô

-&p. I

X X

ccf.

Exp.

/

&=00

o

¡L

\

500

\

X

/A

//

\

/ \L

VI

// \ \

\\

X

"A

\

W

Fig.5. Response amplitude operators of hydrodynmic pressure.

A

I t

(8)

o

=

LExp. li

¿

o

X

_*

X X

b<p.

Jff

(al.

&xp.

o

3«---

L

80'

X

Xx

o

-o

-Q I H I i

r

C.ß

/0

/.2

Í77,> J I I I

7

8

Ú)

(rc//gec.)

F'i.

6. Response

rnp1itude operators of hydrodyrmic pressure.

I J .___.J_. I I J

2,5

/0

¡.2

(9)

o

_/.0

X

Exp.

X X

LE'p. I

X Fig. 7. X X

_A

8 e

/À= /O

5. 2V2

o

-

-X

o

¿J

EXP 17/

Caí

Exp.

o

I i I X

Variation of' amplitude of hydrodynamic pressure with ship speed.

X

---A

o

0L1

i ¿J

¿Ji

o

(10)

Q-

ç

0s

Ò

5(p. I

C)

/

IL/A= I0

14,

d

601.

P-

_o

_X

Exp. ILl

o

L

I

û

o./,Ç O

o.O

O/

Fig.

8.

Variation of aLplitude of hydrodynarnic pressure with ship

speed.

o j-,--L2 F,2

o.ft

/.

X X X

x

)Kp.

H

q L.) X'

Q-1.0

o

)< X

(11)

3.O

Cal

£p.

o

X

2.-)ô___

X

2.û

I. Û

3 xP. i

X

I. O

O L I O

/Exp.If

X 'X

o

e

o

i I O

Exp. Jil

I X. X

o

-o

o

L

i I Û

o.o

0.1

O/LÇ' F,,

Fic. Q

\Jrtion of amplitude of hydrodynamic

(12)

3.O

2...

/.O

QLI

,4.P

- o'.

À =

/

bp.

CaÍ.

o

--X

X

-o

X

/

o

I

O

/ 2