Instructions for use

Title Application of Rankine Sourse Method for Improving Hull Form of Fishing Vessels

Author(s) Kawashima, Toshihiko; Yoshimura, Yasuo; Suzuki, Shirou

Citation Fisheries Science, 68(Supplement 2): 1807-1810

Issue Date 2002-06

Doc URL http://hdl.handle.net/2115/8434

Rights Copyright (c) 2002 the Japanese Society of Fisheries Science（日本水産学会）; ©2002　公益社団法人日本水産学会 The Japanese Society of Fisheries Science

Type proceedings (author version)

NoteProceedings of International Commemorative Symposium - 70th Anniversary of the Japanese Society of FisheriesScience, October 1-5, 2001, Yokohama (日本水産学会創立70周年記念国際シンポジウム「新世紀における水産・海洋科学の展望」, 2001年10月1日-5日, パシフィコ横浜).

File Information RankineSource.pdf

Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP

Application of Rankine Source Method for Improving Hull Form

of Fishing Vessels

-TOSHlHlKO KAWASHIMA'. Y ASUO YOSHIMURA 2 • AND SHiROU SUZUKI'

INational Research InstituJe of FisMries Engineering. Hmaki,Kashima, /baroJ:i,31 4.()421.Japan and 2 Graduate School o/FlSheries Sclence,HoIrkoido Univusiry. M/llQlo,Hokodate,HoIrkaido O41-IJ611, Jopon

SUMMARY: The Rankine source method is applied for improving hull form of a fisheries research vessel. The vessel shookS be enlarged lengthwise. Purthennore, a bulge and a bulbous bow will be added. Effects due to these subjects on the wave making resistance are highlighted. The bulge decreases hull resistance and a physical reason is discussed. The method of optimizing wlge form is proposed and finally an improved hull form with optimized bulge is shown.

KEYWORDS : _ _ • ~othulform. bulgedeolgnlng

INTRODUCTION

A fisheries research vessel. the Ushio Maru' of

Hokkaido University is oow in reconstruction. The vessel should be enlmgod lengtbwise. FW1henn .... oolge and oolboos bow will be added. BIrt the ~ loss due to these reconstructions is one of problems. Because the possibility of increasing resistance due to inCreased ship volume and added bulge resistance is existed. In this plan. exchanging ofttle main engine for a larger power one is not included.

The Dawson's Rankine source method!) which is a kind of the boundary element methods 10 caJculale wave flow around a ship hull is applied for e...aluating the effects of these reconstructions on wave making resistance. Firstly. a flow fteld around original hull is discussed. Secondly, the effects of enlmging lengtbwise, oolboos bow and bulge ore examined. The

fact that the oolge cIe=ases the wave making resistance is fOWl<! out in this process. The physical reason is also explained. Thirdly, a method to optimize bulge fann is proposed and an improved hull form with an optimized bulge is shown. Finally. the results of model experiments in the circulating water chamel ore shown.

An applk:lltion ror. fisberies researcb vessel

This calculation method is applied for the Usia Maru. Fig.l and Fig.2 show wave contour and huD pressure respectively. As common and typical charw:teristics on fishing vessels. the degree of changing of wave and p"""'''' foc huU length dim:tioo through whole ship ~ are larger than fine mercll81lt ships. The height of wave at fore end part is distinguished. Resistance Ilea

at both fore end part and aft part ore w:s:y clear, anoIher thrust area at fore part is little recognized.

In the plan of _on, ship length 4P i. enlmgod from 27.5m 10 33.7m and the original main engine is not ex.changed for luge size one. The voyage speed Ys is planned under the condition of that from original Ys=II.(](t (Fo=O.345) 10 modified Ys=IO.!Ict (Fn=O.283). IIete, Fn is Froude number.

Comparative calculations &Ie tried under the conditions of Casc-I (original). Casc-2(enlmgod),Casc-3(enJarged+buJge) and Case-4(enJarged+bulgo.hllb). Fig.3 shows coetrJCitnt of wave making resistanoe Cw. FigA expresses hull side wave. From view point to

get indications for improving hull (onn, analyzing to the hull side wave is essential, because hull side wave depends on hull pressure distribution din:ctJy.

As effect due to bu1bous bow, distinguished decreasing is got from Casc3-Case4. But from hull side wave, bulbous bow influences on flow field of oneself limitedly, not necessarily wildly over ship hull. This result indicates limitation to improving under the

Fig. I 0 shows Cw correspondingly to results by calculations (FigJ). Effects due to enlarging, bulbous bow and bulge are qualitatively same as in calculations. The existence of bulge effect for decrease of Cw is clear and Cw decreases 14% at Fn=O.283. Fig. I I shows hull side wave. Results of experiments agree with calculations. specially the bulge effect for hull side wave is nearly same as calcuJations(Fig.4). Synthetically throughout above mentioned improvement. the coefficient of residual resistance Cr is possible to decrease about 25% to

original one under 10.0 kt The problem on ~ loss according to the reconstruction in planning is neglected through calculations and experiments.

I .015 r--~-'--'--'--VJ+" .014. r=='""=.'!. -"".st. m-/"",,!.!I<t-l!I'lll"''f''!.!I~1 J4 ,+-',..-j

. 013 r==' =,'!"',.:£!!!! ""-/,,'!U.!oLl f-l!"I!!I""~'-,'" !,.::/,VC-,..-j

<-=-::;"-='+",.",32"'-1"""''',-,-,,311 ~1!f."'0.Ll! II "'i'll/""i.i.'wl ,/-,-' _~ '" . 012 r 1Jf/ . 012

.011 -~: 0.318 II. 51 ,flIOP"'''11J1I-'I'I--I.01l

. 010 -- : .284. c •• 11 ~' +II I ..... uJ.,

. 010

~-+--+---+-f,!'fAff-/I---#/}'1'+/ -I .009 .- .009

: /I II /

"" .004 004 003 . 00' f--+--1I---lIJ-iI f-f--t----1

:.~00::i:~~ii~~:;;JE-.A'::'j=·<I=-tI-1f-=-~-:~I-~-~~ .: : I F., l/lffl .• ,. .000

.10 .15 .20 .25 .30 .35 . .0

Fig.IO Results of model .experiments in CWC

CoDCtuSioa.

1) Rankine source method is applied to facilitate the pl8JUling of several modifications on a fisheries J<SearCh vessel. The vessel should be enlarged lengthwise. Furthennore, a bulge and a bulbous bow

ttllI Si d, Wa" IAppl

0."

0.04 1\ 1= F :., I In.

:tn I ~,., :tn I ", :u I , ,

1\ ... ... : In If"

.\ ~ 1";-~. ,j I~ --

1 ,,,-

0.03

0.02

0.0\

0.00 -0.01

".02

. I -(1.03 0.0 0.2 0.4 .... -

I F. .:~ ... . , ,I, Fn ~:3 ,,. no(). 3 ,I, 1"" F. ."3

'1l$.. "- ~ II ~ .. ~ ~ -- ~-I,e I I

0.' 0.8 1.0 ./4, Fig. I I Results ofmeamrcd hull side wave in cwe

will be added. Results of calculations for Cw and hull side wave are qualitatively in agreement with resu1ts of cwe experiments. 2) Bwge is not necessarily increasing the wave making resistance. Because bulge protects the pressure drop near aft shoulder part of ship. But. the effects of bulge on the flow field is limited locally . 3) Various modifications of the bulge forms are examined and finally a ship with an optimized bulge is

proposed. 4) Gain of effects due to sectional area curve and water

line curve of bulge IUe fll'St order, one due to frame line is second order. 5) The ~ loss due to the longer 1ength and bulge is

neglected Ihrough the present calculations and experiments

The authors would like to thank to Director Y.Yamakoshi, Fishing Technology Division ofNRlFE for kind support and good suggestions in !his study .

Ref ....... I)Oawson,CW., Proc. of 2nd lnlcr. Cont On NwneriQII Ship

Hy<Irodynoml<>(l97l)

2)H.Miyata,et al • .J.K.Insai Soc.N.A)apan.,No 177(1980),No J 79

( 1980),NoI81(1981)

3)T.Kawashima,et al.,J.K.ansai Soc.N.A.Japan,No219( 1993).

No22O( 1994), No23O( 1998),N023O( 1998)

--. --- --------, ---. -.. ,,' , .... , .. , .. .. - - ' -.. .. '.M '.M '.M ... • .... .... ... ... • • .. "

. ~

. . .. .. .. .. "".-1_,.- .. ..

• .' - .. • \""",""':Z-, • rio ,..... .......... j ...

'.0 • •

.. .. .. , •• ,-,....0 .~ ·'_L,.. " .

FigS Modified prismatic curves of hull and bulge ,,-,u

c:,.:..-a--.. _ ...... c;..;..-a __ ......... .....

1.:_ ......... .....

. -~ ,.~ U)

,.~ I.e.. 'J I . e".

~ : ...... - .. _ ......... _.c..,..... · :_-_ ... _-......... -....... _.c.. ........ -,.~lAIo/.·_.II·~.__ (J)

~w: ......... _ ........ ___ ""_~

• •

, " ,. Cr. <,-r •

........-: :_ ... ...... ---: : ......... ~/ :_ .. ,

Fig.6 Modified frame line of bulge

P is weighting function. Calculations to series ships with systematical

modifted bulge form are tried under Fn=O.283. As in Fig. 7, an optimized bulge decreases 9% Cw to original. Fig.8 shows an improved ship with an optimized bulge. Curvature of bulge fonn is stronger than original fonn and cent.,. position of bulge buoyancy is ncar 555. Fig.9 is hull side wave. The difference between modified wave and original one is very little, But improving of pressure near aft part is distinguished.

ewe Experiments for lDSpec:tiOD

Model experiments are tried to check the inspection for results of calculations by using circulating water

.M· ... -.., \ f=L::-~ , w \

I I w ~

, I , ••

~~ ~

~

~

L

•• •• w ~ ~ -

Fig.7 Calculated Cw of various modified bulges

_ .. _-_ ..... -_ ... __ ... Fig.8 Calculated hull fonn with optimized bulge

1\111 SUI Wm (14,> 0.05

: ,,1.1 .. ( ... 1 •••• M'"

0.0 - .- : .'111 •• ~.t •• 1I~00 .~00.5 ~'--I ~ ... • -- : .'10 .. MI .. moO.s .~00.5 U·' __ I~"') ------- : .,11"", ht •• 1I~00 .31000.415 U-2--.I~ •• )

0.0 , 0.02

V\ i\ II

I II' '-.,

0.0

0.00

-<1.0

-<1.0 2

-<1.0 , 0.0 0.2 0.' 0.6 0.' 1.0 .""

Fig.9 Calculated hull side wave of modified hull

channel of NRIFE. Through basic and continual researches3

), the higher qualitative and quantitative experiments are possible under the condition of non steady wave, oon inclination and perfect uniform velocity distribution,

Fig.1 Wave of original hull ~.345)

___ '-__ ,_.~

Fig.2 PJ.ssure of original hull ~.345)

condition only to quip bulbous bow without improving of main hull fonn.

Cw is not necessarily increasing by bulge compaml from Case2-Case3. In this case, it is possible to decrease over whole zone without designing point Fn9>.283. The gain of effect due ~ bulge is as same as one due to bulboos bow. The bulge eflCct for hull side wave is not existed at fore pert, but distinct differences are recognized at shoulder area of fore part

(B in Fig.4~ mid ship .... and shoulder .... of aft port (C in one). As area B is thrust zone due to pressure, bulge increases Cw. But bulge introduces to decrease Cw at area C that is resistance zone due to pressure. As ...... by integrating hull pressur<, to decrease Cw is possible.lt is considered that Cw is increased according to the increasing of ML', UB, Cb and so 011 by added bulge volume. On the other hand as in FigS, shoulder part of prismatic curve is cut due to increase of transverse area of mid ship by bulge. This modiftcation of prismatic curve gives definitive decreasing ofew.

A designing on bulge form

The bulge form is separated into sectional area and frame lines as same as in treating on aft hull form of fine ships byMiyata et 81.2). Sectional area curve of

Qo • • 001 1~/. s..,,"1" 1

,. 0 - - ,-- .- ,- ./

,. -- ,- J...---'" 0 1----- :_--:-C 4 ._-

L /

1.4 1'/ /' --0 ••

-~ /

- - ,-'I/IL I )" 1 0 o. 0.' uti 0.' 0.'

Fig.3 Calculated wave making resistance

tt..11 SI d. Wau l!\..t,l

0.05

0.03

1= t- :., .. , lii : u 1111' ... : In ' t' u"bn .283 : In I " ul vi fn .m

0."

. . I f\ IE, .

" -.... -'I/-11 / " .\ 0.02

0.01

0. "

- -, ~-----<1. 01

".02

-<1,03 0. 0

A I 0.2

• --0.' -- c I~

0.' 0.'

Fig.4 Calculated hull side wave (Fn-028J)

1. 0

bulge. Cpb is exp1essed analytically as in Fig.5. Here Cpb is consisted of linear part and shoulder parts. The shoulder parts are expressed by a cubic curve with conditions of the smooth connection at edges and shoulder points. Furthermore the condition of consta1t

volwne is added. Unknown parameters are length of pa!1IIlel port Ib and the center position of area x ... Positions at fore and aft edges is fixed. Through changing these p8l1IlT1eters, the original Cpb is possible to be produced systematically.

On the other hand, methods of changing of bulge fiame line by Eq.(I), Eq.(2) and Eq.(J) as in Fig.6 respectively are adapted wxler using of Cpb defined as above mentioned. The hI-method gives defonnation for the :zone of frame mainly near the free swface, the b2-method effects emphatically for the zone near the bottom of bulge and the b3-method induced the changing combined with bJ and b2-metbod, here