SCHRIFTENREIHE SCHIFFBAU. Festkolloquium zur Emeritierung von Karl Wieghardt

427 | April 1983 SCHRIFTENREIHE SCHIFFBAU K. Eggers und S.D. Sharma Festkolloquium zur Emeritierung von Karl Wieghardt Festkolloquium zur Emeriti...
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427 | April 1983

SCHRIFTENREIHE SCHIFFBAU

K. Eggers und S.D. Sharma

Festkolloquium zur Emeritierung von Karl Wieghardt

Festkolloquium zur Emeritierung von Karl Wieghardt K. Eggers, S.D.Sharma , Hamburg, Technische Universität Hamburg-Harburg, 1983

© Technische Universität Hamburg-Harburg Schriftenreihe Schiffbau Schwarzenbergstraße 95c D-21073 Hamburg http://www.tuhh.de/vss

INSTITUT

FÜR SCHIFFBAU Bericht

Festkolloquium

DER UNIVERSITÄT Nr. 427

zur Emeritierung

von Karl Wieghardt

K. Eggers S.D. Sharma

Hamburg,

HAMBURG

April

1983

VORWORT Am 31. März 1982 wurde Professor Karl Wieghardt emeritiert, nachdem er an unserem Institut fast über die ganze Zeit seit der Gründung im Jahre 1952 gewirkt hatte. Aus diesem Anlaß wurde ein Festkolloquium durchgeführt, bei dem ein großer Kreis von Freunden und ehemaligen Schülern versammelt war. Wir hatten acht Kollegen aus aller Welt zu Vorträgen über Themen aus dem Bereich der maritimen Hydrodynamik eingeladen. Dabei war aber vorerst nicht an eine gemeinsame Veröffentlichung der Reihe dieser Beiträge gedacht. Da jedoch vier Vorträge bereits in Manuskriptform vorlagen, folgten wir einem mehrfach geäußerten spontanen Wunsch, die Arbeiten in gedruckter Form zu sammeln. Die restlichen Arbeiten werden anderwärts erscheinen, soweit sie sich in der vorliegenden Form für eine Veröffentlichung eignen. So sind die theoretischen Ausführungen von Professor T.Y. Wu über lange Wellen auf flachem Wasser, für welche sich überraschend Zusammenhänge mit dem Bericht von Professor J.V. Wehausen über experimentelle Untersuchungen aufzeigten, inzwischen in erweiterter Form auf dem 14ten Symposium on Naval Hydrodynamics in Ann Arbor vorgetragen worden und werden in den dortigen Proceedings zu finden sein. Andererseits konnte die nicht nur optisch sehr farbige Darstellung von Professor J.N. Newman über seine Durchsegelung des Nordatlantiks aus drucktechnischen Gründen nicht einbezogen werden. Hamburg,

im März

1983

Die Herausgeber

PREFACE Professor Karl Wieghardt retired from office on March 31st, 1982 after nearly thirty years of service in our Institute starting soon after its inauguration in 1952. To celebrate this event an "informal" colloquium had been organized, which was attended by a large number of his friends and former students. Eight colleagues from all over the world followed our invitation and contributed lectures on various topics within the broad field of marine hydrodynamics. We had not originally intended to publish formal proceedings, but the ready availability of four manuscripts has encouraged us to meet the spontaneous desire of several participants to study the material in writing. The remaining lectures will either appear in print elsewhere or are, unfortunately, not amenable to adequate reproduction on paper. Thus the theoretical exposition of Professor T.Y. Wu on long waves in shallow water, which incidentally turned out to be closely complementary to the experimental investigations reported by Professor J.V. Wehausen, has been subsequently presented in extended form at the 14th ONR Symposium on Naval Hydrodynamics at Ann Arbor in August '82and will appear in due course in its Proceedings. On the other hand, Professor J.N. Newman's colorful slide-show on his sailing cruise across the North Atlantic had to be omitted for purely graphical reasons. Hamburg March,

1983

The Editors

2

Festkolloquium anläßlich der Emeritierung von

Professor

Dr. rer. nato Karl

Wieghardt

am Montag, dem 29. März 1982, im Institut

für Schiffbau

Pro

-

9.00

9.30 h

der Universität

Hamburg

9 r a mm

Ansprachen

Prof. Hansjörg Petershagen, Direktor des Instituts für Schiffbau Prof. Hansjörg Sinn, Senator für Wissenschaft und Forschung Dr. Peter Fischer-Appelt, Präsident der Universität Hamburg

-

9.30 UDer

12.30 h

die

Prof.

Vorträge

inkompressible

Klaus Oswatitsch,

(Vorsitz:

Prof.

Potentialströmung

Technische

Klaus Eggers) im Staupunkt

Universität

spitzer

Körper

Wien

Ships in Very Shallow Water

Prof.

John V. Wehausen, University

of California,

Berkeley

Kaffeepause The Science

Prof.

Nonlinear

Prof.

and Art

of Wave

Klaus Hasselmann, Long

Forecasting

Max-Planck-Institut

für Meteorologie,

Hamburg

Waves

Theodore Y. Wu, California

Institute

of Technology,

Pasadena

Imbiß im Institut 14.00

- 17.00

Calculation

Dr. Eiichi Design

h

Vorträge

of Ship

Frictional

Baba, Mitsubishi

of Devices

(Vorsitz:

Dr. Som D. Sharma)

Resistance

Increase

Heavy Industries

for Improving

due

Ltd.,

the Wake Flow

into

Dr. George E. Gadd, National Maritime Institute,

to Surface

Roughness

Nagasaki the Propeller

Plane

Feltham

Kaffeepause On the Characterization

of Complex

Flows

Dr. Jürgen Kux, Universität

Hamburg

A Sailing

Atlantic

Prof.

View of the North

J. Nicholas

Newrnan, Massachusetts

Institute

of Technology,

Cambridge

3 Begrüßung

durch

den Direktor

Herrn

Prof.

Meine

sehr verehrten

Petershagen

Zum Kolloquium Dr. rer. nato Institut

Damen,

aus Anlaß

verhindert;

ich darf

lich begrüßen, trotz

Ihnen,

immer

Herren

Senator

Staatsrat

begrüße

sehr knappen

auch über den heutigen

deuten.

Mein

heutigen

Interesses

besonderer

Tages.

Veranstaltung, Ihren

und so danke

Beitrag

Erlauben

zur Gestaltung

Sie mir nun einige

gemacht

Anlaß

an der Arbeit

Gruß gilt auch Anlaß

herz-

hier

zu uns zu sprechen.

am besten

unseres

als

Instituts des

Kolloquium

ist sicher-

entsprechende

Art der

ich vor allem dieses

hinaus

den Vortragenden

Ein wissenschaftliches

lich die dem heutigen

ist

Dr. Fischer-

Terminplanes

Ich darf

Ihres

Bilstein

daß Sie es möglich

Begrüßungsworte

ein Zeichen

Sinn

ich Herrn

zu sein und einige dies wohl

von Professor

ich Sie in unserem Herr

aber Herrn

und ebenfalls Ihres

darf

begrüßen.

und ich danke

haben,

meine

der Emeritierung

Karl Wieghardt

sehr herzlich

Appelt,

des Instituts,

auch

Ihnen

für

Tages.

Grußworte

an unsere

ausländischen

Gäste. I welcome

our foreign

lecturers. on this

I thank

special

guests

and especially

you for your

occasion

which

our foreign

readiness will

to present

surely

make

lectures

this colloquium

a success.

Bevor

ich nun das Wort weitergebe,

Anschluß Danach

an die Begrüßung wird

Kolloquiums Darf

ich nun

Herr Kollege

darf

eine kurze Eggers

ich sagen,

Pause

machen

die Leitung

daß wir im werden.

des eigentlichen

übernehmen. zunächst

Sie, Herr

Staatsrat

Bilstein,

bitten.

4 Ansprache

von Herrn

als Vertreter

des Präses

und Forschung,

Meine

Staatsrat

Prof.

sehr verehrten

lieber

Damen

Ihnen

und der Bürger

unserer

Vorredner

Senator

Dort

tagt wieder

Thema

Sinn,

unsere

ist schon

eines

republik

im Wissenschaftsrat Hamburg

heute

die letzte

bedauert drückt einen

sich darin

Wie wichtig

Ihres

lagen

vor

Jahre

aussetzungen In einer nische

Thema

ist,

sind,

für die

und daß soeben

wird.

Kolloquium

Der Präses sehr.

morgen

Das

von ihm

erhielt.

so habe

im Laufe

vergleichbaren

Die Anfänge

morgen

in einern Gebäude

am Berliner

ist, haben

der Geschichte

erfahren.

ich mir heute

30 Jahren

geschaffen

Hochschulbau

hautnah

mit den jetzigen

Universität

auch

Vorentscheidungen

eingeläutet

von diesem

sozusagen

der Ingenieurschule ziger

in Bonn

soweit

aber

die gerade

Interesse

Herr Wieghardt,

Instituts,

lassen,

einige

wurden,

ein funktionsgerechter

Instituts

wissen,

ein in der Bundes-

aus, daß ich noch heute

aus Bonn

Sie, verehrter dieses

Sie werden

dazu

in Bonn.

die sich mit dem

interessierendes

Tagen

Abwesenheit

Gremien,

daß dies

getroffen Runde

und Forschung,

sind, möglicherweise

von besonderem

seine

Anruf

der vielen

ungemein

und daß in den letzten

worden,

ist. Er ist zur Zeit

Kollegen,

Deutschland

des Senats

hingewiesen

für Wissenschaft

oder Deutsche

Stadt

darauf

beschäftigen.

ausländischen

Wünsche

Stadt.

verhindert

Hochschulbau

Sie Hamburger

und Herren,

sehr gern die besten

der Behörde

Herr

für Wissenschaft

!

Ich überbringe

daß der Präses

der Behörde

H. Sinn

Herr Wieghardt

Von meinem

Bilstein

noch

im Hinterhof

Tor, bis zu Beginn

Gebäuden

sagen

bessere

der sech-

räumliche

Vor-

wurden. Situation

Hamburg-Harburg,

ist zur Zeit noch zwar nicht

die Tech-

in einern Hinter-

5

hof, aber

doch

brauchbaren

Gebäude.

ich anmerken, wohl

dieser

Für unsere

die letzte

wenn

zu verringern

bzw.

die im Süden

neuen

in diesem Die Zielsetzung Hamburgs

Defizit,

aufweist,

In dem bisher

dieser

Universität

17 Professoren

mit ihren

Mitarbeitern,

wird

TU-eigene

Gebäude,

gebaut

das das

ganz Norddeutschland

zu beseitigen.

darf

Hamburg-Harburg

sein wird.

Gebäudekomplex das erste

Gäste

Universität

ist es, das naturwissenschaftliche wie allgemein

funktional

Hochschulneugründung

Universität,

Land Hamburg,

auch

ausländischen

in der Bundesrepublik

Technischen

wird,

angernieteten,

daß die Technische

vermutlich

Jahrhundert

in einem

angernieteten

arbeiten

bereits

und in wenigen

das Technikum,

Wochen

übergeben

werden. Meine

Damen

und Herren,

insbesondere

auch

technik - einen Forschungsschwerpunkt es in diesem Ich glaube,

Gebäude

weitere

das dürfte

für die Schiffs-

der TU Harburg

gute Arbeitsmöglichkeiten

für ein fachkundiges

gute Nachricht

sein.

Die bisherigen

Anfangserfolge

gen parallelen

zum Institut

dieser

neuen

räumliche

eine

Universität

zei-

für Schiffbau:

Mängel

-, wenn

geben.

Auditorium

Wenn

Engagement vorhanden ist, lassen sich Mängel insbesondere

wird

-

-

persönliches

ich meine

auch mit großer

Mühe,

überwinden. Meine

Damen

und Herren,

strukturelle

Defizit

pauschalität

gilt

gen Abteilungen Institut bisher aber

genauso

der Fachbereiche

bestand.

von Ihrem

gesprochen.

etwas

Institut

Neben

und Chemie

eini-

ist das

der Universität

weniger

als einem

der Mathematik

Gebiete

Bei dieser

technisch-naturwissen-

die im Rahmen

Fächer

wie verschiedene

zu machen.

Physik

die einzige

Man hat dabei

auf das bisherige hingewiesen.

es, Einschränkungen

Einrichtung,

treffend,

Gebieten

Norddeutschlands

für Schiffbau

schaftliche

ich habe kurz

der Physik

respektvoll,

Hamburg dafür

"Zoo" von vielen gehören

zu ihnen

neben

den klassi-

6

schen

ingenieurwissenschaftlichen

Was an Ihrem wird

Institut

bereits

Bereichen. vorhanden

mit der TU Hamburg-Harburg

erhalten:

Die Erfahrungen,

Einrichtung

wie die Ihre

Funktionieren arbeit

dieser

Hinweise

geben

tungen mehreren

anderen

Es wäre

schön

technischen

sammeln

wissenschaftliche

ausgerichtet

wenn

Doch wird

in Hannover diese

Lassen noch

einmal

meine

ein Wort

Dank

Stelle

wie Ihr

in diesen

Institut.

der Verträge

Tagen

eher äußerliche

entscheidend

mit

schiffs-

hätte

statt-

Terminsache

ist, für Hamburg dieser

Arbeitsbedingungen

wie

Bereiche

in

und -möglichkei-

läßt.

Sie mich,

richten.

Einrich-

lokal~sierten

daß die Konzentration

und bessere

wertvolle

die Unterzeichnung

wie geplant

Zusammen-

auf Zusammenarbeit

für Ihr Institut, ten erwarten

für das

Denn wenige

lassen;

gute

werden

wie für ihre

sich verschmerzen Hamburg

Ausweitung

in Hamburg

der b~sher

können.

konnte,

so ausgeprägt

ist,

so interdisziplinäre

Hochschule

Hochschulen

Bereiche

adäquate

Hochschulen

sind

gewesen,

zur Umsiedlung finden

können.

in Hamburg

die eine

neuen

mit den anderen

seine

und eingespielt

Damen

und Herren,

des Dankes

für die 30jährige

des Instituts,

bevor

ich schließe,

an Sie, Herr Wieghardt, Tätigkeit

an verantwortlicher

mit der Sie seit den Jahren

aufbaues

in Lehre,

Forschung

leistung

entscheidendes

des Wieder-

und wissenschaftlicher

zur jetzigen

Stellung

Dienst-

der Einrichtung

beigetragen haben - sei es im Rahmen der alten "math-natFakultät",

sei es in der formal

Selbständigkeit

der Jahre

der Dank besonders Berechnung, mich

geradezu

licher

mit ein, was

Konzeption

im U-Bahn-Bau,

seit

organisatorischen

1970. Für Hamburg Ihren

Beitrag

und Dimensionierung

vor allem prototypisch

Dienstleistung"

größeren

aber beim

betrifft

für die Gesellschaft

zur

bei der Belüftung

Elbtunnel.

für das, was mit

schließt

Das ist für "wissenschaftzu bezeichnen

ist. In zwei Jahren

wird

das traditionelle

Symposium

des

"Office

of Naval Research" in Hamburg stattfinden - sicher kein

7

alltägliches ner Anlaß, weiterhin tätig gesützt

Ereignis. Ihnen

Es ist für mich

für Ihre Bereitschaft

für die wissenschaftlichen

zu sein und ihre Belange auf Ihre Erfahrung,

Ich wünsche dazu allen

aber auch willkommezu danken,

Einrichtungen

in internationalen

auch in Hamburg Gremien,

zu vertreten.

Ihnen,

sehr geehrter

Herr Wieghardt,

Erfolg,

dem Symposium

einen

guten

persönlich

Verlauf!

8 Ansprache

von Herrn

Präsident

der Universität

Ladies

Hamburg

and Gentlemen

It is indeed you,

Dr. Fischer-Appelt,

a great

the great

at this

pleasure

family

of shipbuilders

fine Institute

It is very

early

of Naval

who had official

to attend

last night.

rather

early

for me to welcome

and naval

Architecture

in the morning

for those ning

and honour

this morning.

for everybody

business

and I am glad

and especially

or private

Nevertheless,

architects,

undertakings

you are used

to beg in-

to be with

you again

of Professor

Wieghardt

this

morning. This

is a colloquium

occasion

in honour

of his retirement.

Wieghardt

was born

in

in Vienna. But he was brought up in Dresden where his

1913

father You,

was appointed

Professor

engineering interest master

Professor

Wieghardt,

and advanced

in advanced

gen, where

you worked

your

tute you also World

international after

your

England

and Germany

offered

a position

at this

It was,

für Schiffbau

which

you finally

longer

the pressure encouraged

you

worker

in the

research

insti-

the Second Laboratory

I suppose,

a unique

so short

to bridge

time

the gap

In 1952 you were

at the Hamburg

accepted

you to come

on to Göttin-

After

this war.

and charm

special

Research

You helped

as an assistant

Your

of the Max-Planck-

habilitation.

after

mechanical

the famous

a research

for you especially War.

University.

In Göttingen

in the Admirality

World

later

Prandtl,

and became

experience

between

strongly

you

Professor

1949 to 1952.

the Second

resist

brought

a forerunner

completed

from

in that city.

the time you spent

War you worked

in England

to study

and flow research.

doctorate

During

began

physics

with

Kaiser-Wilhelm-Institut, Institut.

at the Technical

later

physics

of mechanics

completed

who

Professor

on the

after

you could

of Professor to Hamburg.

Institut no

Weinblum This decision

9

was certainly large

not an easy one for you.

laboratory

and exchanged

in those

days was a rather

But with

the aid and support

Foundation,

the Institut

became

known

throughout

the world.

in this

abroad,

is sufficient

Wieghardt,

you remained

were

respected

and became

Together

and your with

of Hamburg, founding and,

fathers

Architecture will

probably

the support

it will and will greater

institute.

University

a very

great

from Hannover

at the Technical

area

and be

by your

today

in your because topics future

as one of the have my support persons

future

work.

I believe related

and

to this

in Hamburg.

institutes

Naval

I say

Naval field

So when

join us and we establish

a solid basis

of Hamburg.

of the University

You will

University

be one of the major provide

example

themselves.

enjoy

of all responsible

and all the other

our colleagues institute

Wieghardt

to the future

have

among

your

be continued

as president

Professor

of this

looking

followed

but

pupils.

of the Hamburg

this also

not only

teacher

certainly

work will

in

the world,

and researchers

all of us here,

I thank

I think,

bodies

that your

several

here

You were

all over

pupils

But you must

Professor

universities,

Institute

of a good

teachers

You are now retired. colleagues

field

You,

and

in it. Although

for this.

some of your

institu-

of the leading fact.

of this

the reputation

And

similar

to you by other

in your

well-known

to know

share

member

Research

from this country

of this

you especially

enjoyed

students.

proud

today,

offered

by experts

among

The presence

evidence

a devoted

Harnburg. Thank you also

here

of mathematics

of Harnburg University

esteemed

have had a decisive

professorships

your

field

which

in a backyard.

and the German

für Schiffbau

and highly

experts

place

of the faculty

of this university

tions

it for an institute

desolate

and science well

You left a very

a new

of Harnburg-Harburg, of Naval

for cooperation Architecture

Architecture within

has a good

the tra-

10

dition

in Hamburg

Marine

research

and is matched

this

area

effort

mineralogy existing

that will

will

work

Research

of us all.

Areas

Our future

Vergnügen

Zwölf

Jahre,

auch

meinem

schon

in Hamburg

anläßlich in Ihrem

ein längerer.

verbunden

-

Ihrer

Leben

the already and 94 be

ein ganz großes mit einem

Hauch

ich werde dies nachher Emeritierung

überreiche.

gewirkt

ein kurzer

haben

will

!

zusammen

Jahre,

haben,

this

to the benefit

ein Abschied

die wir in Hamburg

sind vielleicht

projects

Herr Wieghardt,

von Trauer, daß ich Ihnen heute die Urkunde

Technology)

is in the sea

und ein wenig

tun

to establish with

In

and

and the Atmosphere),

promising

lieber

geology

together

(Marine

the Ocean

out very

Es ist für mich,

98

a new special Processes".

of geophysics,

area which,

between

to carry

"Oceanic

We hope

studies.

of our university,

to establish

be called

together.

research

(Interaction able

we are trying

the departments

new special

related

is one of the strongholds

and at the moment research

by other

haben,

Abschnitt,

die uns hier uns öfter

in

gemeinsam

zusammengeführt

in Ihrer Arbeit, zuweilen auch in meiner Arbeit - und am Ende in gemeinsamer Wissens

Arbeit,

und seiner

und im weiteren schaft.

die uns verbindet

Vermittlung

Sinne

Dieses

Stück

aller

das zu ihren

bedingungen

gehört,

sich angelegen

sein

der Schiffbauer, schönen

Faches

Ost und West, zu feiern, sondern möglich, bare

Stückchen

verbindet. aus Nord

weiß

Ich wünsche wohl

mit auch

Gesellja Lebens-

für Schiffbau

alle

große

so viele

Kollegen sind,

nur Sie allein

dies

zu danken

Ihnen Ihren

im Kreise

Ihrer

dieses aus um Sie

mit Stolz,

und, wenn

noch viele

Kollegen

stets

Familie

Institute

und Süd hier versammelt nicht

Studenten

nur unserer

Es ist eben eine

sicher

neuen

das die Universität

Institut

Daß heute

die Universität

Gelassenheit,

unserer

Bedingungen,

die rund um die Welt

der Zusammenarbeit

den Familie.

nicht

wesentlichen

lassen.

zurückzugeben.

Jahre

Bürger

hat dieses

das erfüllt

auch

zum besten

Internationalität,

verkörpert,

in Erkenntnis

frucht-

und ein so reizen-

11

Antwort

Meine

von Herrn

Damen

Prof.

Wieghardt

und Herren

"Zwei Seelen wohnen, ach, in meiner Brust". - Das kommt daher, schon

daß wir hatten,

entwickelte Jahre,

-

heute

als wir noch

sitzen

haben.

Reptilien

sich tumorartig

merkwürdigerweise

neocortex

mir

ja zwei Gehirne

waren.

erst vor einer

die ratio

und die Logik,

über Verdienst

Das neue Million

In diesem und die sagen

ganz deutlich, daß ich

-

geehrt

das wir

halben

nur beim Menschen.

als Schiffshydrodynamiker weit

Das alte,

werde,

um mehrere

Nummern

zu sehr. Andrerseits, zwar auch

im alten

die warmen

Gehirn,

und heißen

des Gedankens

Blässe

eitlem,

Männchen:

alten

Und in der Tat,

da hausen

den ich mir selber

Gefühle,

angekränkelt

sind.

Ist das nicht

es ist schöner hätte

danken.

ausdenken

Allen

ten für die freundschaftliche Jahre

lang,

jetzt

Institutsangehörige,

danke

ich den Veranstaltern

Rednern gekommen

bei manchen

und Freunden sind.

die nicht

wunderbar

-

30 Jahre

Wunschtraum,

Kolloquiums

und Studen-

über viele

lang.

Studenten.)

dieses

und Kollegen,

!

Ihnen allen nur

Zusammenarbeit nicht

von

können.

Institutsangehörigen

bis fast

und

Und die sagen mir

als der schönste

Deshalb kann ich - trotz aller Bedenken sehr herzlich

die Gefühle,

(Ich meine

Ebenso

warm

und allen

die von nah und fern

12 Die inkom ressible Strömun

am Stau unkt schlanker Sitzen

Klaus Oswatitsch

1. Einleitung

Die Untersuchung sei auf stationäre inkompressible Potentialströmung beschränkt. Bei den geläufigen Theorien für nicht angestellte schlanke Profile, Rotationsrümpfe oder Flügel wird mit Quellbelegungen der Körperachse oder Körpersymmetrie-Ebene gearbeitet. Die vereinfachten Randbedingungen führen dabei an Profil-, Körper- oder Flügelspitzen zu einem sprunghaften Beginn der Quellbelegung. Dieser hat jedoch eine logarithmische Singularität für die Geschwindigkeit an der Spitze zur Folge. Die Geschwindigkeit wird am Belegungsbeginn nicht Null sondern negativ logarithmisch unendlich, vgl. etwa [1J, S.443 und S.458. Dieser

Fehler

Körperspitze

beruht

sprunghaft

Strömungsrichtung auch nicht

gravierend

Stark

Flügelspitze kann

spitze

einer

als konstant

digkeitsbetrag Potenz

Während

des Abstandes

Theorie

an der Keilspitze,

einer

Strömung,

schlanker

dieses

die Umgebung

einer

Körper

Mangels

soll

auf Strahlen werden.

Diese

mit der reinen durch

Längen-

durch

die Kegel-

Eigenschaft

hat

aber auch der Geschwinkonstant

mit einer zu. Diese

also bei der ebenen

Sie ist keinesfalls

eines

oder

Uberschallströmung

die Spitze

Strömung

die man mittels

Körper-

In Ermangelung

von der Spitze

schon

Fehler

werden.

bei letzterer

auf Strahlen

der skizzierte

es doch unbefriedigend,

Die Begegnung

angenommen Strömung

an der

daß sich dort die

Wenn

so erscheint

Kegelspitze.

er bei inkompressibler

beherrscht.

ändert.

die Strömungsrichtung

gemeinsam.

nimmt

wird.

die Quellbelegung

sondern

bei einer

entspricht

die inkompressible noch

ist,

kurz dargelegt

vergrößert

maßes

beginnt,

selbst

wiedergegeben

im folgenden

daß nicht

sprunghaft

daß der Staupunkt falsch

darauf,

konformer

positiven

Eigenschaft Strömung

Abbildung

auf schlanke

ist,

Spitzen

tritt

zutage,

völlig beschränkt,

13

wird uns aber besonders zur Lösung unserer Aufgabe dienen.

2. Separationsansätze Die Geschwindigkeitskomponenten

seien

durch

ein Potential

dargestellt:

=

u wobei

v

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o surf ICt .. 1

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10 z so 5 u.ttlv Fig. 9 Measured mean velocity distributions at station 7 (on the floating element) for different free-stream velocities on rough surface no 3

78

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82

Design

of devices

for improving

into the propeller

the wake

flow

plane

G.E. Gadd

This paper

relates

if the boundary unsatisfactory occur

most

forms

as dealt

with

twin

or shaft

layer wake with

development perhaps, forms

brackets causing

annoyance

and discomfort

warships,

unacceptable

Ways

of avoiding

fatigue

design

regions

of unduly

Sometimes

however

would

be acceptable

is then necessary ships

attaching major

its manufacture

Such problems arise

shadows

ship however

from bossings

For both

types

damage

to the ship, with,

as well

involving

as

in the case of

noise.

vibration

excited

to ensure

vibration

is by

there

are no local

in the flow entering

the propeller

which

that

it had been

a eure.

In such cases

eure has often

fin above

of ship and

thought

turn out not to be so in practice,

a successful

structure

to an

screw merchant

of radiated

designs

to devise

a large

leads

flow can be vibration

propeller

low speed

may arise

They can also

excited

of the stern

disco

single

to the crew,

propeller

careful

plane.

if the wake wake

levels

which

the hull

are excessive.

The best way of avoiding

screw

with

of unsatisfactory

possibly

over

in this paper.

screw warship support

problems

in the propeller

commonly,

the result noise,

to the serious

been

the propeller.

considerable

and attachment

and it

for single

effected

by

This however

is a

cost and difficulty

in

to the hull.

Flow deflectors A much

cheaper

applicable

alternative

either

to single

method screw

of curing ships

the problem,

or to twin

screw

ships

83

with bossings, is to fit flow deflectors. In the two full scale cases with which the NMI has been concerned to date, /7/ these have been relatively small cambered aerofoils welded to the hull (fig. 13). In the first such case these deflectors made a considerable improvement and in the second they cured the problem completely. However the positioning of such deflectors is critical to their success, and in the cases just quoted this was only achieved after making initial full scale trials with less successful arrangements. There is therefore a need to devise reliable model technique for determining an optimum arrangement of flow deflectors before fitting these to the full scale ship. The present

describes

some experiments

(the most

successful)

case mentioned

to develop

a technique

such that

second hoped

predicted work

paper

from the results

on the full scale.

in any future arrangement the need

The stern

in the case

This made

it especially

arrangement such astern

boundary

layer

by Gadd's defrectors 5 and

method

flow speed

the

enabling

tended

difficult much

would be used

a successful

fig.

away

and avoiding

flow

deflectors

5 m waterline

to the bulbous

of

on the model

contours

calculated

of the flow deflectors.

situated

in the region

trailing

edges

be in a region

than on the ship, whereas

The

of the 3,

on station

to the calculations would

de-

tank models,

variations

to occur

type.

the best

towing

girthwise

14 shows wake

their

that according

scaled

on ordinary

are likely

with

on the model

could

to determine

larger

on the ship were

It can be seen tors near

considered

/1/ at the plane

7 m waterlines

have been

the same technique

tank tests with

Thus

It was

experimentation.

thickness

than on the ship.

it could

to the ship straight

by tests

for with

above.

to the

that the deflectors

may arise,

to be fitted

The reasons wh y towing are unreliable

flector

Then

case which

for full scale

obtained

relating

3/4.

the deflecof much

lower

there would

84

be much smaller differences for the 3 m and 7 m levels. Moreover at the 3 and 5 m waterlines the flow angles at the hull surface are predicted to be considerably different on the model from those on the ship, as can be seen from figs. 15 and 16. Thus the calculations suggest that the model scale flow deflectors at the 3 m and 5 m waterlines will behave differently from the full scale ones.

Experimental At least

confirmation

at the model

to be qualitatively

15, shows

the predicted

that these

ones.

to earlier

boundary

layer

Moreover

Thus

tank,

agree

same hull

quite tunnel

form,

on this model

ones,

appear

of a photograph

as indicated

one of the wind

measured

from the predicted

predictions

the tracing

directions

was of this

profiles

predictions

the theoretical

in the towing

referred dissimilar

scale

correct.

of flow directions in fig.

of theoretical

by tufts, well

with

models

and are not too

as can be seen from

fig.17.

Foreshortened models with correct afterbody shape The above discussion has shown that it is hardly surprising that difficulties were experienced in correctly predicting the full scale behaviour of flow deflectors from tests on exactly scaled models. It would clearly better to use a model which, whilst having the correct afterbody shape where the deflectors have to be fitted, was distorted upstream in such a way that the boundary layer flowing over the deflectors approximated more closely in its thickness and flow angles to that on the full scale ship. This led to the consideration of a distorted double model as shown in fig. 18. (It is shown here in its final test configuration in a cavitation tunnel, as discussed below.) Ideally, the flow in the propeller plane of such a model should resemble that on the ship, but the natural unmodified flow might not do this, so that corrective

85

devices might have to be attached to the model. Any such devices would have to be placed weIl forward of the flow deflectors which it was required to test.

Calculations to assess whether flow corrective devices are likely to be required To give a preliminary indication whether or not such corrective devices were likely to be needed, further calculations were made. Hull surface flow directions on the fore shortened model were predicted as in fig. 19 to be even more upwards at the plane of the flow deflectors than those on the full scale ship, suggesting that an artificial cross-flow in the boundary layer might need to be introduced. Propeller plane wakes were also calculated for comparison with those calculated for the undistorted model and ship. Such calculations are at best very crude, and as can be seen from fig. 20 they fail to predict the narrow but quite intense wake in the upper half of the propeller disc on the undistorted model. This narrowed wake can be associated with the streamwise vorticity generated by the bulbous stern, and although this in itself is predicted quite weIl (fig. 15), its effects on the wake are not. The prediction for the full scale case (fig. 21) appears to be even worse, though here we have only a scale-corrected wake with which to make comparison, and the validity of the correction procedure is perhaps open to question. Despite the inaccuracy of the predictions in figs. 20 and 21 however, the difference in character between these predicted wakes and that predicted for the foreshortened model in fig. 22 is sufficiently marked to reinforce the suggestion that corrective devices are necessary for the latter model. The comparative lack of streamwise vorticity in the afterbody flow has led to a wake which is wider at the top and narrower at the bottom than for the undistorted hull. In fact the predicted wake is not too unrealistic for the foreshortened model as can be seen from fig. 22: the measurements shown there were made in the course of the experiments described in the next section.

86

Wind

tunnel

experiments

For the present whether

realistic

results,

tunnel,

it was

this model

intended

should

comparison

and error

experimentation

much

more

was

tested

insert

time,

tunnel

working

seetion

in the two faeilities. established

tunnel.

For future

applieations

especially

where

not be neccssary may weIl

be sufficient

significantly

the wind

it would

simply

A wind

model

be tested

flow

tunnel

tunnel,

is

the model sleeve

approximately thus

the ensur-

be assumed that any

therefore

be duplicated

would

model

to be obtained

naked

There

hull wake,

it

which

then be no necd

in the octogonal

in the normal

it may

Instead,

arrangements would

in the

technique,

quickly,

pressures.

effeetive

this wake.

tunnel

it

the necessary

an octogonal

to find deflector

improve

to test

with

cavitation

a realistic

However

Aecordingly

simulated

tunnel

have

to measure

establishing

tunnel.

of the foreshortened

results

arrangements,

at the same blockage ratio

operate

It could

cavitation

after

fitted

in the wind

pressure

to find the apprcpriate

of the cavitation

would

give

that

results.

to perform

for such a purpose.

in a wind

ing that the model

wake

cQnsuming

as in fig. 23. The sleeve

cireular

flow deflector

in the cavitation

eonvenient

could

fluctuation

the full scale

trial

devices

enable

with

very

to

in the cavitation

various

have been

model

from the outset

with

would

correcting

it was desired

be tested

18. This would

to be measured

for direct

where

model

or not the foreshortened

as in fig.

levels

foreshortened

investigation,

establish ultimately

with

wind

sleeve tunnel

insert

working

seetion. The first

part

of the present

eonsisted

in attempt

it beeame

elose

the right

hand

to modify

to the assumed side of fig.

fitting

aperforated

in fig.

18 for the final

made

experiments

plate

the flow steadier

in the wind

the bare model

wake

so that

full scale

ship wake,

21. The first

improvement

to the aft model

cavitation

and slightly

tunnel reduced

tunnel

support,

shown

involved as shown

configuration. the wake

on

This

intensity,

87

perhaps due to an alleviation of the adverse effects of tunnel blockage in the rather constricted working section. The measured wake shown in fig. 22 was with this plate fitted, but it was clearly still far from the required one of fig. 21. The closest approach to this that could be obtained, after many trials of alternative arrangements, was with a pair of vortex generators, similar to but larger than the scaled flow deflectors, at station 11/2 near the 3 m waterline, as in figure 18. These produced longitudinal vortices inducing an artificial cross-flow in the boundary layer to simulate more closely the required flow. The vortices were very concentrated for a short distance downstream of the generator tips, where they could be visualized by tufts which rapidly spun round. However vortex bursting then seemed to occur, with the vorticity becoming more widely diffused. This took piace upstream of the flow deflector position. Thus it could be assumed that if the propeller plane wake was realistic, the boundary layer flow at the flow deflector plane would also be sufficiently similar to that on the full scale ship. This would mean that the flow deflectors could be expected to behave in a similar way on the model as on the ship. The final

effective

as can be seen it was

certainly

generators. proceed

naked

hull wake

from a comparison far better

It was considered

to the investigation

of the wake

induced

achieved

was not perfect,

of fig. 24a with

than without

fig.

the upstream

to be sufficiently of the additional

21, but vortex

realistic

to

modifications

by the flow deflectors.

As mentioned above, two deflector arrangements were tried on the ship, one with the two lower pairs of deflectors sketched in figure 18, and the other, more successfully, with the additional upper pair as weil. It was conjectured however that the two upper pairs of flow deflectors, or conceivably even the top pair alone, would also have been effective. Therefore it was decided to investigate these arrangements as weil as the ones actually used on the ship.

88

The resulting wakes are shown in fig. 24. It ean be seen that the biggest improvement over the wake with no flow defleetors is produeed by the 3 pair eonfiguration, as aetually used on the ship, but the two upper pairs of defleetors give nearly as good a result. The two lower pairs give a signifieant, but more modest, improvement, and there is also some improvement with the upper pair alone. Thus

on the basis

expeeted

that

the 3 pair

defleetors

would

and noise,

that

benefieial, produee

of the wind be very

a small

or upper pair

the upper

experiments

2 pair

benefieial

the two lower

and that

tunnel

it would

arrangements

for alleviating arrangement

of flow vibration

would

pair of defleetors

be

be quite

alone

would

improvement.

Com arison with towin

tank ex eriments on undistorted model

Different eonelusions would however have been reaehed from tests on exaetly sealed defleetors on anormal towing tank model. Fig. 25 shows that although the three defleetor arrange~ ment produees a signifieant, though less marked, improvement than that shown in fig. 24, the arrangement with the two lower pairs of defleetors aetually makes the wake slightly worse. Thus it would be expeeted to be of no benefit at all on the ship.

Cavitation Pressure tunnel

tunnel

experiments

fluetuation

levels

at the refleetion

eorresponding

to ballast

123 rpm. Fig.

26 shows

withforeshortened were measured

plane

above

eonditions the harmonie

dimensional

pressure

fluetuation

the various

flow defleetor

model

in the eavitation

the serew

at eonditions

on the ship at 115 and eomponents

levels

arrangements.

K

p

=

of the nonp/p n2D2

for

89

The results broadly confirm the expectations of section: Wind tunnel experiments ..., page 5, as inferred from the measured wake flows of fig. 24, though the upper pair of deflectors alone appears in the pressure measurements to be about as good as the two lower pairs, whereas the latter arrangement would have been expected to be better than the upper pair alone, according to fig. 24.

Comparison

with

ship results

Results are available for the ship in ballast condition with no flow deflectors, with the two lower pairs, and with all three pairs, and in load condition with all three pairs of deflectors only. Qualitatively pairs ment

gave

the finding

some

is borne

gland

improvement

shows

the results

big improvement speed

is reduced

pair

configuration

hull

configuration.

figures

on the other measured fig.

29.

those

refer

and the three

pairs

a big improve-

levels

measured

fluctuation

pairs

levels

more

the stern

is a considerable

pressure measured there

on the model

levels

is good

seem

things

speeds

however

to make

a

at 123 rpm, at that

the three

over the naked

28 are considerably

tests

in fig.

26. These

In the load condition,

agreement

and on the ship,

28

level

improvement

in fig.

as fig.

worse

vibration

condition.

also measured

confusing,

in the model

to the ballast hand,

gland

at the stern were

of deflectors

(fig. 27). At both

The non dimensional than

the two lower

at 115 rpm but to make

the fact that

larger

draft

are somewhat

that the two lower

despite

in ballast

out by vibration

(fig. 27). Pressure

and here

that

between

the levels

as can be seen

from

90

Possible

causes

One obvious figs.

of differences

possible

explanation

model

does

the ship.

Certainly

than

not simulate

that

aimed

peak

at, shown

in fig.

in fig.

fig. 28, and for the apparently

deflectors quite

in fig.

similar, the main

that

the model

26. However

cause

are much

The scale

are for a level

the ballast

case,

An alternative

explanation

of air bubbles then.

and may

are not

These

ment

was considered

ship

cavitation

tunnel

the effects

of such entrained pressure

bow, which along

in

levels

under

similar

causes

to

entrainof the

to simulate

and this may well

at ballast

the

condition.

do not attempt

bubbles,

breaks

and bubbles

air bubble

in the ballast

tests

quan-

pressures.

is closely

in /8/, where

experienced

a great

immersed

to be one of the primary

The present

scale

from

between

the cavitation

is fully

The bow for this

for the ship discussed

why the model

that this

from those

may be carried

affect

the bulb

fluctuations

indicate

and the model

condition

at the bulbous

bubbles

that

pressure

also

is different

different

in the ballast

significantly

formed.

here

be expected

29 shows

for the discrepancies

is formed

In the load condition

would

are

26.

26 and 28 is that

the surface hull

fig.

of

the wake

it would

be noted,

not much

reduc-

and load wakes

in modelling

of plotting

in fig. 26

excessive

too low. Fig.

26 and 28, it should

predictions

tity

the ballast

less

account

by the 3 pairs

for the load condition

which

is not the case.

figs.

about

of the discrepancies,

tests

levels

that of figs.

brought

flow deflectors

so if such a deficiency

were

pressure

levels

that on

21. This might

compared

in the pressure

on

24a is a little

pressure

tion

without

between

accurately

for the lower with

levels

results

flow deflectors

sufficiently

the wake

and shi

of the differences

26 and 28 is that the wake without

the model sharp

between

draft

be

are lower

than on the ship.

Be that as it may, even if quantitatively

the results from the

foreshortened model are judged to be in error, they give a qualitative picture of the effects of the various deflector ---...--

91

arrangements which is substantially correct. It is felt, therefore, that such a technique is a useful one to use in any future tests of flow deflectors for curing vibration problems, and as suggested, wind tunnel tests alone, with assessment of the resulting wakes, would probably be sufficient for this purposes.

Concluding remarks The experiments described in the foregoing are examples of how useful the wind tunnel can be as an adjunct to the investigation of what at first sight my seem to be purely hydrodynamic problems.

Acknowledgements This work was supported by the Ship and Marine Technology Requirements Board of the Department of Industry, HM Government, UK. Acknowledgement is also due to the industry sponsors of the recently completed PHIVE programme.

References

/1/

Gadd, G.E.:

"A Simple Calculation Method for Assessing

the Quality of the Viscous Flow over a Ship's Stern". Paper presented at the International Symposium on Ship Viscous Resistance, SSPA, Göteborg, Sweden, 1978.

/2/

Klebanoff, P.S.:

/3/

Bradshaw, P.:

NACA Report 1110, 1952

"Conditions for the existence of an inert-

ial subrange in turbulent flow". search Council R&M 3603, 1969.

Aeronautical

Re-

/4/

Townsend, A.A.: "The structure of turbulent shear flow". 2nd edition, Cambridge University Press, 1976.

/5/

Odabasi, A.Y. and o. Saylan: "GEMAK-a method for calculating the flow around the aft-end of ships". 13th Symposium on Naval Hydrodynamics Tokyo, 1980.

92

/6/

Kline, S.J. and A. McClintock: "Describing uncertainty in single-sample experiments". Mechanical Engineering Dept Standorf University, Jan. 1953.

/7/

Gadd,

/8/

Takekuma, K.: "Effect of air bubbles entrained from bow on propeller induced pressure fluctuation". Mitsubishi Technical Bulletin No 140, June 1980.

G.E.: "Flow deflectors - a curve for vibration". The Naval Architect, No 6, 1980, P 238.

-

Fi g

.

13

93 -

SKETCH

OF

BE I NG

FITTED

FLOW TO

DEFLECTORS 51-11 P

7m

7m

Sm

I

I I

3m

O.7m

FRO

HULL

~\

07m

FROM

HULL

-i

J I J

\ \ \

\ \ \ MODEL

SCALE

Fig.

14

FULL

PREDICTED

WAKE

CONTOURS

AT

PLANE

OF

SCALE

FLOW

DEFLECTORS

3m

-

._HULL.

94

_--

SURFACE

,

3,,,

Sm 7m

-

EOGE OF

80UNOARY

LAYER

"2

-

---

--

--

-

3m

--

--- ---Fig.

15

CALCULATED AND MEASURED FLOW DIRECTIONS MODEL IN BALLAST CONDITION

7m

HUL.L. SURFACE

-

3/"

_ _-

EOGE

OF

FOR

BOUNOARY L.AYER

-

Sm

3m

-

,.,---

Fig.

16

CALCULATED CONDITION

--

---

FLOW DIRECTIONS

FOR SHIP

IN

BALLAST

95

o

120

\00 Z, mm 4'3Sm

W...TEAL.INE

80

(;)

60 .

o

40

20

0-8 u / Uo

'-0

60 Z. mm 40

'-45m

W...TERL.IN!: (;) (;)

20

o

Fig. 17

CA!..CUI."TEO aOUNOARY

PEAFOR"'TED

e 0.6

0.2

0., U/Uo

\'0

CURVES COMPARED WITH MEASUREO POINTS FOR L"VER ON '130 SCALE MODEL AT STATION 3/4

PL TE TOP OF TUNNEL. ;,---PERFOIIATED I I I

PLATE

I I

VORTEX GENERAT 3

;;

,l4 , I '2

I

2

SHIP

,

'y

l

5

,~AAAL.L.EL. SECTICN I I

Fig.

18

DOUBLE

HULL

FORESHORTENED

MODEL

IN WATER

TUNNEL

51. 2

-

-

96

HULl.

-

SURFACE

___

EOGE OF 8OUNOARY LAYER

---

7m

Sm

:!Im

--

.--

-Fig.

Fig.

19

20

CALCULATED FLOW DlRECTIONS FOR FORESHORTENED MODEL WITHOUT UPSTREAM VORTEX GENERATORS

PROPELLER PLANE WAKE CONTOURS AT MODEL SCALE: LEFT, PREDICTED: RIGHT, MEASURED

-

97

-

Fig.

21

PROPELLER PLANE WAKE CONTOURS AT FULL SCALE: LEFT, PREDICTED: RIGHT, INFERRED FROM MODEL SCALE MEASUREMENTS

Fig.

22

PROPELLER PLANE WAKE CONTOURS FOR FORESHORTENED MODEL: LEFT, PREDICTED : RIGHT, MEASURED

-

-

98

WATER

TUNNEL

SECTION

OCTACONAL SLEEVE INSERT

SUPPORTS FOR INSERT

MAIN WIND TUNNEL SECTION

Fig.

23

OCTAGONAL

INSERT

TO

WIND

TUNNEL

SIMULATING

CAVITATION

TUNNEL

180'

180.

180.

(0)

(bJ

(cJ

180'

WORKING

110'

Fig. 24 WAKE eONTOURS IN UPPER PART OF PROPELLER Dlse IN WIND TUNNEL c, LOWER 2: d. UPPER2: c. UPPER 1 '"'UMBER OF 'pAIRS OF FLOW DEFLECTORS: 0, NONE: b.3:

SECTION

- 99 -

(b)

(0 )

Fig.

25

WAKE CONTOURS IN UPPER PART OF PROPELLER DISC IN TOWING TANK NUM8ER OF PAIRS OF FLOW DEFLECTORS: 0, NONE: b,3: c, LOWER 2

-OJ

~p '01

0

~~I :/ 3 4-

:/ 3 4

0

b

-03 Itp -02

-01

0

(cj

:/ 3

10

1 :2 34

. .

115 rpm

1 :2 3 4-

Fig. 26 PRESS URE MEASUREMENTS ON MODEL NUMBER OF PAIRS OF FLOW DEFLECTORS: a, NONE

1 :2 3

c

:< 3

'-

FOR b. 3

J1L I :/ 3

10

d

10

xBR

C

1:/3rpm

JlJl

~-~

1 :< 3 4-

BALLAST CONDITION c. LOWER 2 : d. UPPER

I :/ 3 'I.

2:

I!:, UPPER

x BR

1

-

100

o

b

c

mm/s

o

Fig.

1 2 3

JL , 2 34

J"

I 2 3

J"

IC BR

27 PEAK VERTICAL VIBRATION VELOCITY AT STERN GLAND ON SRIP IN BALLAST CONDITION AT ]23 rpm. NUMBER OF PAIRS OF FLOW DEFLECTORS: a, NONE: b, 3: c, LOWER 2

O'r .0. '0

115 rpm

I

o'r

oJ

-J I 2 J .. 0

JL

..~ I

2 1 ..

1 :2 3 ..

MODEL.

SHIP

.008

JI SA

b

'0

'0.

'05 121 rpm

'0 '0.

o '03

Fig.

'02

'0,

0

Fig.

1 a 3 ..

1 :2 3 4.

,

2 J ... 11eR

28 PRESSURE MEASUREMENTS ON SRIP IN BALLAST CONDITION.NUMBER OF PAIRS OF FLOW DEFLECTORS:

a, NONE: b, 3: C, LOWER2

29 PRESSURE MEASUREMENTS FOR LOAD CONDITION WITR 3 PAIRS OF FLOW DEFLECTORS AT ]23 rpm

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