Pressure on ground due to the ship's travel

0X1)erilÌlefltelle? t i Weg erfolgen müssen. Aiií3ertlein ist (1er

Be.reich extremen Fachwassers

_{bisher tioch wenig}

er-forscht

Literatur

(lj liarras, (Y. Ii.: 'Its- l'lienotiiena of _{Sii(i) Squat. Internatioucl Shipt iuildhig} Piogress, Rotterdaiii 26(1979), No. 294, S. 44-47.

I)and. J. W.; Fergu8on, A. JI.: The Squat of Full Ships in Shallow Water. The Naval Architect 1 (1973)4,8.237_253.

Tack, E. O.: Shallow Water Flows past Slender Bodies. Journal of Fluiti Mechanics, 26(1(196')), s. 81 93.

Leiva ron bref. G.: Tiefgangs- und_{Triiiimwinkeliinderungen von Schiffen} unter Berücksichtigung endlicher Wttssertiefe und Einilull auf tite Steuer-liarkeit, Biss. A an der I'akultüt für Mathematik._{Naturwissenschaften und}

Technische Wissenschaften dm-y_{Wilhel,ii-Pieck-tiniversitlt Rostock 1981.}

[3) Neuman. J. Y.: Laierai Motion_{of a Slender Body between Two Parallel} Walls. Journal of luid Mechanic's 39/1(1969)5.97-117.

161 FujIno, M.: Experiruemital Studies_{on Ship Maneuverability in Restricted} Waters, l'art I. International Shipbuilding

Progress. Rotterdaiti 15 (1968) 168. S. 279 301.

17) Fujlno, M.: Maneuveralmilimv in Restricted _{Waters: State of time Art} University of Michigan, l)ept. of Naval Architecture anti Marine

Engineer-ing, Report No. 184, 1976.

[S] Kleinav, D.: Querkraft und_{Gieritiomient infolge Schiebewinkm-1 und} Batir,-kr(irmirnung an SchRien hei hesehrSirkter _{Wars-erl iefe. Schiffhauforsciiung,}

Rostock 22 (1985) 3. S. 133- idO.

)t)J Jt7einau, D.; ¡'ils, D,: Experimentelle_{Methoden zinn Eintlul3 von Fiach}

Pressure

_{on ground due to the ships travel}

wasser auf die Steuerbarkeit von Schiffen. Sch,iflbaimforschung. Rostock 22 (1983) 3,8,147 155.

[101 .korvi,t-A'roukocski. B. V: Jacobs. II. 1f.: (ircumitferentially Noti'Untform Ship Propeller Inflow. International Stipbuiiliig Progress, Rotterdam 4

(1(157) 38. S. 520-530.

Ill] Ko,rin-Kroakousk), B. V.: Smm'rii-Propeller-Interaclion with u Strear,linm-Body of Revolution. International Mhiphilding Progress, itotterdait 3 (1956)17. 5.3-24.

[12] l'oh!, ¡Ç, H.: tcber die Wechselwirkting zwischen Schiff uni l'ropeiler,

Jahr-buch der Sehlifbautechnischen (im-seilschaft 55(3961).

[13) _Vowackl, H.: Polentialtheoretische Ströntungs' und Sogherechnungen für schiffsähnliche Körper. Jahrbuch tIer Schiffbautechnischemr _{(lesellsci,af t 57}

(1963), S. 330,

[34] Dreger. it'.: Ein Verfahren zur Berechnung des Pott-olialsogs. Schiffstech-_{nik 6(1959) 175, 5. 173-187.} [15] Jsay. It', H.: Der Schrauhenpropehler siate der freien_{Wasseroherfl9che timid}

in Fiachwasser. Ing-Archiv 31(1962). 5. 194_213.

Id] ltereldsmuu. ¡f.: Determination of the_{dynaa(c properties ali] the propeller} excited vibrations of a special ship storti_{arrtiligeuent. International} Ship-building Progress, Itotterdar,, Vol.11 (11164), S.121.

1171 Gulche. F.: Untersuchung von Sc'hifl4schrautlerx in schräger Anströmung. Schiffbauforsc]iung. Rostock 3(1964)3/3,S.97-122,

[18] OThan,. I'.: Nachstrountnessungen _{an einen, Schiffsniodm'll her Serte 00.} IfS'Bericl,t Nr. :140 der Hantburgischen

Schitfhauversuu-hsausialt, 1971).

1191 .'chumil:, G.: Erprobung des Rundlaufkatials it,_{Institut fur} Strömungs-lehre tier Universität Rostock. Wis. Zeitschrift_{der Umiiversiliit Rostock 13} 119(14). Math.'Nnturw. Reihe. Heft 1,8. 103 119.

2(1] .ltartln. H.: Pule, l): Vertical forces, trin, unoruents aliti changes of draught and Iritis of ships in shallow water. Schiffhauforschnng, Rostock 25(198613, 5)135-159,

TECHNE MFTBT

LaboratOfiUm or

Sthm.thWI

Archief Mekeiweg 2, 2628 CD 0.111 TeLi 015- 786873 - FlIc 015- 781838 Dr.-ing. H. Jiart',i, Prof. Dr._{se. teehu. Dieter Pvls, Wilhelmoi.Pieck-Ut,ivv'rsitv,}

Ship Technology Section. liostock

i - Aim of the investigation

J)tte to travel of the ship and due

_{to the resu[ting flow.}

especially because of the huoyancv effect, pressure is

induced OIS the surface of the _{ship and its surroundings. In} shallow water this pressure can produce consielerable local stresses on the ground. The knowledge of this is necessary

to fix up the sufficient enough dimensions of the water.

ways. The constructions like tunnels or canal bridges, which

are total1' or partially situated nearhv,

_{must withstand} h hone stresses. Besides, this knowledge _{of pressure can be} usod for the detection of the position of a ship.

The distribution of the

_{pressure anti its magnitude are} being influenced by _{so many factors stich as the form of} the ship, its path amici position, _{speed, propeller loading and} water depth as svel[.

Experiments to measure this _{pressure are quite expensive.} Because of the influence of so many parameters on tile results, there arc limitations_{to achieve generaliz.etl results}

in this way [I], [2].

It is therefore appropriate_{to look into theoretical mnethotis}

for solving this probietit.

Front the solution of similar ship _{hydt'odynaniic probleitis} like the calculation of flow

_{around ship's body for the}

determination of changes of draught and trito in shallow

water [3], [4] and the calculation of flow in the space

around ship fut' calculating tise hydrodynamic interaction

between ships, it has been found that the application of

frictionless fluiti methods proved its usefulness.

It was to he expected that. _{time influence of viscosity011 the}

pressures induced uy ship on ground with increasing

distance front ship will get diiiiinished.

By comparing theoretical and _{experimental results this}

hypothesis will l)e examined.

2. Fundamentals of the theoretical_method

In the following, the essential fundamentals of the developed

theoretical method are presented in a short form. Details

eau le found in a nunil,er of works lotie by the research

tMl)) ''i\Ianoettvrahility of 51mips'' itt the _Wilheliii' Lieck-University 1-tostock for the soluttiomi _{of other proiiletns of} potential theory, to miamise _{a few [1 to [71.}

IVith regard to the underwater_{fom'tmi of the ship. mio rest} rb-tioti is inll)ose(l. The proptilsion _{is dune bs' a singlescrew.} The ground is assumed to be flat. _{it is lying iti the depth H}

parallel to the undisturbed

_{rvater sumrface plane. Fig. I.} The speed of the ship relative to water at rest is considered

to be so small, that the influence of the waves on the

))ressiire. distribution

_{can be neglected. According to}

measurements, this assummnpt bu

_{is valid at Fn =}

_gL

0,25, Fn = 11w! _0.6.

The SlliJ) is moving on straight _{put h wit.houti I t'ift angle.} The fluid motion is assumed _{to be fti't ioniess and} jrrota-tional. Foi' the flow calculation _{a coni' hjuiate svstetti w'hieh}

is fixed ois the ship uni at

rosi is _{.1 osen. The t'lui ire} itiflow to the ship has a velocity _it-,.

eliìp so/c'

í,.ao oarr e/s

Fig. I. Patti distribution of an equur'alent etlipsoid and coorditite systdin

-76

To meet the 1)oundarv coII(litions iii

the plane of the

tlndisturìJe(l water surface and the ground, th

mirror principle is applied. Then the flow through a spatial lattice consisting of seit infinite nutlÌl)cr of ship hulls in the (listance of 2 H is to be calculated. rriìerefore a continuous distril,u.

tion of sources and sinks is arranged on the hull surface.

In the propeller plane sink-panels are arranged.

j '.

Pactel cl ist ributions on the surface of t he

Ships usai for the investigations

Tite integral equation for the determination of the so far unknown source intensities is solved nwnericallv. The surface of the ship and lite siiìgularitv clistriluit ion are

cliseretisized iii an _{ai >propriate way. For} titis, panel

distributions as in [] are used. In Figs. i and 2a, b, e

examples of the panel distributions for different ships and for an equivalent ellipsoid are sitowic.

Oiiet' the siiigu1urit _{distribution is known, the velocities} in utiv 1)01111 of the flow fich I cari be caletIlate(l.

The pressure is doterituined using Rerruoulli's equal iou.This uiìetluod also allows apl)lieat.ions to ships withnuore than one propeller and for tot iou on curved pat lus with drift, angle. 3. Theoretical and experimental results

The aim of the theoretical work was lo investigate the

influence of essential parameters on t he pressures induced

by the ship on the ground as systerivaticallv as possitle.

In particular, the following pai'aiueters were varied fornì of the ship

thrust load coefficient CsO

=

-'j- e ii Ap

ratio of wat ei (le 1)tl t t o I tItI Ighi t. H ¡T lateral dist aruce fini ì ì t lu ship v/J

As sou te stri iigeii t _{restrictions concerning the )roperty of}

the fi oid alu 1 kine tiatics of i totion are introt I oecd, special

attention was paid to a eottuprehiensive comparison of

theoretical ttiid experitilent al results.

The jei experituiental results [J], [2] were kindly left. to the disposal of t he authors by Prof. Heuser,

Versuchs-anstalt fib Uiniìeiuschuiffbaii I)iiisburg, Federal Republic of Get' ì tati.

it n very t ut i'rest ing experil t cii t the liressitre distribution out t lie t uit ¡tel itioler the river Elbe in Haut burg dite to the j assage of \l / ''Kolsiunreuu'' wits liucast ired. The results are

shown in Fig. 3. l'ue nondi titensional pressure coefficient. -sl)

e1 _{IS J)rCselited} ¡LS ii fuiictutt of lli

itOu-2

t liiiit'iusjortul x/L-c(,ortl ittute fixed with t lu' ship. 'l'ue lesti Its are coi iq)aret I wi iii t Itose frot ii model experiu i teilt S, in which a uiiodel of Maritter-tvja' ship was used, siuice its

fornì is very sititilar to ti tat

(if M/ "Koisnaren''. The agreellien t is quit e good.

03

02

Co

Fig. 3, Presure distrit,utioit scent ding to theory and to ttodcl and full -cale test yjS -0063 ,'1crer'H1T-Iß3 e,er,-<ee(nrnfl,eC

-

v',eo'y e*zenr'-,ent t?' oysrrn - - thOrv eeoer,1ent

Fig. I. Prctsuru dtstrttsition at two d'flèrcuit tritttsof tite Mttriuter-type ship

As to ite expected, itt higher H/T ratios effects of boutitlary

Iayou' amid _{'utI' fields are of uiìiluor iiiiportanee. As} t ut'

thrust load coefficient of the propeller iii the e.xperilluents

is unknown, foi' the calculations it was varied in the

expected range. With exception of the immediate

sur-roundings of the propeller, the calculated results under the sterti and iutids}tip range aI)l)t'oaeh the nieasutred ojies with illcreasiuug thrust load coefficient. The theory u'eprodoces

the influence of trins by stern on pressure (listribiltioiu in

the right tendency. As to be expected, the ttutderpressure

grows at the sterzi witlu iltereasing trim, since the distance

between the ship nuit! the ground gets diitiinishoel there,

Fig. 4.

The retIitctiouu of the press res induced by the sitip with increasitug distance of the utiidship is showtu in Fig. 5. While there are very little changes of the pressures under the bottoni of the sit ip, t he pressure distortions itre

de-d'casi tug with i ¡tcre'iisirtg distance outside this range. Furt Iteru i toue, a httuikettriiet' was used lot' the in vestigattons.

Titis fort ti was citosen since it lias au essentially higher ful muss with ci O,S4 and a longer prisi nat je lìuidsIuiJ) l'auge COluI aired wit lt the Mariner Shti1) vttli e t 0.63 and a relatively short prismatic ¡t tiilshi1u tange. 'rite (liffeteltees iii formo cause clear pressutit' titiniliva ou the b,ottottì itt the range of shoulders. The tuuiilerpressiuu'e tlecreases utittleu' the

uttielship muge. Figs. 6 II, The experiments wit lu tite bulk-carriel' were carried out al 'eu'- shallow vater. This could he-' a reason for houuuidarv laver influences ori t lue pressiut' distrilnutiout oui t he groom I. The gap betwecut t lii' bottoni of tite' sltiit auth tluc grotiuutl is i'etlueetl by the displaceuuuont.

thickness of the bouiudarv laver

atiti therefore li ighter

underpressiures are causee!.

Atu approxittlate calculntiouu of e lisplaeeuiuellt t hickruess gave results uup to 50 per cent of the gulp. Tite changes of du'amtght

alle! triti t _{'hiclt llave tuot been colusi(leretl ill the cedciulatiotts}

cause the salute tentleutev.

-03 -t" 0053 0592 0, 99,í. ¡522

FIg. 3. Pressure distributton at diflèretit Itt eral distances of tite Yutariuter'type ittip

Jig. C. Pressurc distrittitt ui dii.' It,t It, t 'ayej uf (hie hulkearrie'r ,tttder tite keel

7 _{Schtffhauforcc'hurtu Zui 2}

-at -02

X

-10 -08 -36 -04 -02

Schi tTbaulorsch un 2ti 2 I

eq 0.8 0.5 04 02 -0,5 05 36 0--0.2- --0.6 X 05 1,0 06

Fii. '. l'reoouredi-trit)utioII due to tite travel of tite hulkearrier near the ship

Fig. S. Pressure tlitrihution nue to tine travel of the lnnilkearrier under tIne keel

0 02 Q-. ¡ Q6--_Q8 1.0 ( .''/L ¿23

Theory

x es-peri HiT- 7,1 yjB- 0.8?L6 -08 C50- ,23 Theory -W 35 Xes-perw7leflt

l'fg. 10. Pressure distribution due to the travel of the hulkn'arrier tinder the keel

Cp I 0.8 0G QL -02 o -0.2 ---04 0,6 -08

-t5

-Qe

II. Pressure distribution due to tite travel of the buikearrier hear tine ship

05 1.0

)Ç1Lp9

l'fg. ft. Pressure distribution due fo the travel of t ne liulkearrier near the ship F44). 12. Pressure distribution underuind tiearequivaleiitelljpsoids

C50 - Lh.3 - Theory .x es-oerrnen-,t H/7- Q?5 v,'a -0 25 70 00

- ><-T ¡375 yI.SQnS?45 7) 0,8 0.5 QL 02 02 0,2 04 0.6 _Q8 1Q

Fl,. 13. i'resure di,tributioi, duc to 1h travel of a pusher train under the keel

Tite ¡)ressIlre itijittit ta at tite sliotililers at. '/i) = O are cal-citlated wit h u quite good accuracy. lt sliotib I i te noticed that there are higher itntlerpressures at the shoulders iii tite

forepart than l,e}tiiol At t lie three given H/'l'-rutios even

at v,'R = 0.M746 values of e1, up to neun 0.6 are reached.

To siiutplifv flow calculai joua, sottie authors, for instance

[9]. piopost' replacing the ship by equivalent ellipsoids. The ¡rent investigations offer the possibility to exuLt tute

the usefulness of t his assuuuuupt ion. The (lo(ul)lc 1)0(1v of tite i,ulke,trrier vas repiaceul at first b t spheroid and titen by

art oI,iate ellipsoid. Tite spheroi I Itas tite saune T/L-rat io

like the ship, tite oblate ellipsoid also the saine B/L. Tite result s for the pi-essuire distribution uit HIT = 1.1 and at

¿ ijifereutt lateral distances are shown in Fig. 12.

Tite pressure ¿ljstril,uutiorì shows a (lifferent tendeutcv coin-pareti with that of the ship. The absolute ruiuiiuuIluui lies in tite uttiddle lange at x/L =0. lt is iutarked far less distinctive. Tite I)ressui-e decreases with increasing lateral (listance at a higher rate ut the ellipsoids than at the ship. By using an oblat e ellipsoid instea, i of n si theroi(i, no considerable ii rtproveuuients turc- achieved.

lit connection with t he installation of a false bottor tu into

tite experimental facilities of tite departuitent of naval architecture, tite stress to be expected thining the passage of a rrtdl was calculated.

1. Einleitung

Heir ut Bet rie h voit Zweihanger-Ludegescht irren wird eine Erscheinung beobachtet, die eine sichere Führung (les Lade-baumes durch die Hanger nicht iiehr gewährleistet. Dieser Zustand ist. dadurch gekert nzeichnet. laß eine Hangertaije, in deut ,uìeisten U'ällen tier I iineniiucnger, scheinbar lose fällt, d. it. kraft frei wird. Der Ladei,aurut wird dann nur noch voit einem Hanger iii seiner Lage gehalten. In dieser Situation

ist eine sichere Führung tier Last nicht. mehr rutoglich. Aiiuilieite Ersciucirt trugen I rotoli ait (ieri i lordwippkrauten

As an extj-eiiue case of tite ship foriits which cari be

iitvesti-gat.ed, a pusher train with a high L/T-ratio und a high

block coefficient was considered. Due to the long prisrutatie midship lange the pressure coefficient is reduced to almost zero, while the pressure lnaxiuuua have the saine oc-dei- of

niagnitude as at the ship. The method of solution includes

a l)roceciure, in which tite number of reflections to meet the boundary condition at the ground with a given accuracy is evaltititetl. At vel-y shallow vater, for a long, flat form of a ship a high number of sucht i-eflections is uteeded. Therefore

t.he calculation of the given pusher ti-aia is rather tune-consuming, a Cl'U-tiune of 475 minutes is required on a high-speed computer of ES 1056 type at HIT = 1.25.

4. Conclusion

Usiitg tite assumption of frictionless flow, the pressure distribution on the ground due to the passage of ships was

calculated. The influence of undei-water form of the ship, of the P10l)eller loading, of the draught-to-deptii ratio and

the lateral distaitee from the ship was investigated. A colnl)arison s-ith experiruuetutal iesult.s shows a good agreentetit with tite exceptiout of very shallow water. lii

titis case the influence of boundary layer iii the gap between

tite bot tolti of the ship an(l tite ground cauises increasing

Iifferenees. References

L 1) Gro1li,u. IF. Srelterur,g des altert Ell'turtiict - Vergleiclterlule

Modellittes-suriugeru zut l3odendruuekrnessungeii itt der uroltausuiilinmg. Versuehs,utstalt

für !tirtrtenscltiffl,a,t l)uishurrg, Vfll)-Berie}tt 086. I)uishurg l'J8J

l:il Groliius. IV. Sicherung tlei tulten Elhttritttels (II) - Trirtumn-,

'ttaeflkurtun-tutti Itødend ruckrttessurigert hitter extreti temi 1lacltwasserbedimrgutugeit. Ver-surcltsan-talt für Biirnenchiffhatu 1)uishurg, VJtI)-Jtericltt 1004. Duisburg ins i.

]:l] Le Ira em ¡kìrCt. (,.: Tiefgarug-- und iri,nntwjrtkeliinulerujtgems von Schiffer, im, flacitern \Vaseer unti Einfluß auf die Sucuerharkeit. Dissertation (A) an der

Wilhelmn-Piec-k-trtiversitlt Rostock. Sektion 5cltiflterhmtik, Rostock 1984. ]4] .ilartlut. H.: f)er Etutlua des Propellers auf Kräfle und Mortiettle an

gt-steuer-ten Schiffen bei flachem Wasser. Dissertation (A) ait der Wilhelm,u-Pieck-tniversität Rotock. Sektiort Schiffstechnik. Itostoek lost;.

I:,I Raabe...Hydrodyriturttisclte Kräfte und Mom,uente infolge Wech,elwirk,tntz

zwischen zwei Schiffen und iltr Eurthlutu ¿turf ¿lie Steuerhtu-keit. 1)iasertation (A)

att dec Wiltuelrti-Pieck-Uuiversität Rostock, Sekt ion Scltifftechtnik, Rostock

1984.

6) ¡'518, D.: Hydrodyrtantiscite Krâfte utt,h Monuenute art Schiflèn und Voraus-sage volt Scltiffsbeweguitgemt. T. L2. S'-ewirtscttaft, Berlin 17 (1985> 11, 5.549 553; 18(198C) L 8.31 33.

I 7] H.. Pale, D.: Vertical forces, tri,,, ritotttertts amtd changes of dra,rght and trot, of sitips fit shallow water. Seltiffhauforrs-hrurig, Rostock 23 (1986) 3, S. 155-139.

[S] Heu, J. L.: .,,tit/,. A. M. 0.: Calculation of Nontliftintg Po(ential 110w about Arbitrary 1hree-Dirttension,al Bodies. Journal of Shtip Resettrctt 9 (11)64)

8.22-44.

[9] BasIn. A...lu. a.): H ydrodynarnlcs of ships itt s1taIlo

vater....Sudo-stroetuie", Leningraul 1976.

Mitteilung uler Ingenietuhochschule für Seefaltrt Warnemuüntle/Wustrow, Wissenschaftsboreickt Konstruktionsleltre und Maschinenelemente

Dr. se. tecitn. H.-J. Günther unid Prof. Dr. se. techn. G. König

iteint Aufitolen ties Krutitausiegers itt die obere Endluige auf. Die Wipptaije wird ,,krtift frei". Der Ausleger kamt durcit

die Wipptaije nicht, mehr sicher in seiner Lage gehalten

werden. Es kommt zum tJberschwingemi von Ausleger und Last in Richtung tier Ki-ansiiuile.

Die nachfolgeitt I I >esciiniei,ciie,i theoretischen und

experi-u tìetttellemi Uni ersexperi-utcitexperi-ungen erfolgen amexperi-ut Beispiel voit

Zwei-It anger-Ladegeschirren. Die verwendeten Methoden urnd Verfahren sind ebenfalls uittf Bordwippkrane

anwend-bar. Schiffhauforseliun 2G 21987 pr ¿ -pusher rcin t>

HIT2

-f,25 '-i 02 u -t

-s

0,5

-

f -0.'. -l6 Li

Beitrag zur Untersuchung der dynamischen Führungssicherheit von