教学课件伊斯坦布尔技术大学：高级推进系统13 Supercavitating Propellers.pdf

AdvancedPropulsionSystem

GEM423E

Week13:SupercavitatingPropellers

Dr.AliCanTakinacı

AssosciateProfessor

in

TheFacultyofNavalArchitectureandOceanEngineering

34469

Maslak–Istanbul–Turkey

1

Contents

•Cavitation

•SomeHistoricalAspects

•Supercavitation

•FeaturesofSupercavitatingFlows

•SupercavitationFlowProblems

•SupercavitationModelling

•CavitatorHydrodynamics

•DesignofSupercavitatingPropeller

•TheStoryofSupercavitatingScrewPropeller

WhatisCAVITATION?

Theappearanceofvapour

bubblesandpocketsinsidean

initiallyhomogeneousliquid

medium,occursinverydifferent

situations.

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AnotherDefinitionforCavitation

•“Cavitationisthebreakingofaliquid

mediumunderexcessivestresses.”

•Thatdefinitionmakescavitation

relevanttothefieldandmethodsof

continuummechanics.

•Itisconvenientforcasesinwhichthe

liquidiseitherstillofflowing.

AnexampleforStillLiquids

•Asolidbodywithsharpedgesadisk,for

exampleissuddenlyacceleratedbya

shockinstillwater.

•Bubblescanappearattheveryfirst

instantsintheregionneighbouringthe

edges,whenthevelocityoftheliquid

particulatesarestillnegligible.

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AnexampleofFlowingLiquids

-Flowinventurisorinnarrow

passagesvalvesforhydraulic

control.

-Flowneartheupper-sideofa

wingorap