外文翻译关于二级液压节流锥阀的低汽蚀研究Word文档下载推荐.docx
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外文翻译关于二级液压节流锥阀的低汽蚀研究Word文档下载推荐.docx
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外文翻译
学生姓名
学院名称
机电工程学院
专业名称
指导教师
2011年
05月
27日
Researchonlowcavitationinwaterhydraulictwo-stagethrottlepoppetvalve
Abstract:
Cavitationhasimportanteffectsontheperformancesandlifespanofwaterhydrauliccontrolvalve,suchasdegradingefficiency,intensenoise,andseverevibration.Two-stagethrottlevalveisapracticableconfigurationtomitigatecavitation,whichisextensivelyusedinwaterhydraulicpressurereliefvalvesandthrottlevalves.Thepressuredistributioninsideamediumchamberlocatedbetweentwothrottlesofatwo-stagethrottlevalveisinvestigatedthroughnumericalsimulations.Theeffectsofthepassagearearatioofthetwothrottlesandtheinletandoutletpressuresonthepressureinsidethemediumchamberareexamined.Thesimulationresultsindicatethat(a)thepressureinsidethemediumchamberisnotconstant,(b)thelocationsofmaximumandminimumpressuresinsidethemediumchamberarebothfixed,whichwillnotvarywiththepassagearearatioortheinletandoutletpressures,and(c)theratioofthepressuredropacrossthefrontthrottletothetotalpressuredropacrossthetwo-stagethrottlevalveisnearlyconstant.Thecriticalcavitationindexofthetwo-stagethrottlevalveisthenestablished.Asemiempiricaldesigncriterionisobtainedforthewaterhydraulictwo-stagethrottlevalve.Thecorrelationbetweenthecriticalcavitationindexandthepassagearearatioofthetwothrottlesisinvestigated.Relevantvalidationexperimentsareconductedatacustom-manufacturedtestingapparatus.Theexperimentalresultsareconsistentwiththesimulatedones.Furtheranalysesindicatethat(a)thelargebackpressurecanimprovenotonlytheanti-cavitationcapabilitybutalsothetotalloadrigidityofthewaterhydraulictwo-stagethrottlevalve,(b)anappropriatepassagearearatiowillbebeneficialforimprovingtheanti-cavitationcapabilityofthewaterhydraulictwo-stagethrottlevalve,and(c)thewaterhydraulictwo-stagethrottlevalvewithapassagearearatioof0.6wouldhavethebestanti-cavitationperformancewiththelowestriskofcavitation.
Keywords:
computationalfluiddynamicssimulationcavitationloadrigiditypassagearearatiotwo-stagethrottlevalvewaterhydraulics
1INTRODUCTION
Waterhydraulicsystemsareoperatedwithrawwater(puretapwater)substitutingformineraloil.Theyhaveadvantagesintermsofdurability,reliability,safety,andcleanness.Suchsystemsarebecomingmoreandmorepopular,especiallyinfieldsofsteelandglassproduction,coalandgoldmining,foodandmedicineprocessing,nuclearpowergeneration,oceanexploration,andunderwaterrobotics[1–5].
Becausetheopeningofawaterhydrauliccontrolvalveisverysmallcomparedwiththatofoilvalve,thewaterflowvelocitythroughthewaterhydrauliccontrolvalveislargerunderthesamepressurecondition;
thuscavitationerosionmayoccurduetothehighvapourpressureofwater.Cavitationhasanimportanteffectontheperformanceandlifespanofwaterhydrauliccontrolvalve,suchasdegradingefficiency,intensenoise,andseverevibration.Previously,anumberofstudiesontherelationshipsbetweencavitationanddischargecoefficient,thrustforceandpressuredistributionsinthevalves,andmitigationofcavitationdamagewerecarriedoutthroughincreasingoutletpressureofvalves,modifyingshapesofthrottles,addingstagesofvalves,selectinganti-corrosionmaterialsforparts,andcontrollingmaximumfluidtemperatureandflowvelocity.Tsukijietal.[6]investigatedcavitationbyflowvisualizationinhydraulicpoppet-typeholdingvalvestoreducecavitation.Somemeasureswereemployedtodiminishnoiseandcavitationthroughcontrollingflowrate,upstreampressure,downstreampressure,andvalveliftincaseofconvergingflow.
Aoyamaetal.[7]studiedexperimentallytheunsteadycavitationperformanceinanoilhydraulicpoppetvalve.Itwasfoundthat,asabsolutevaluesofthevariationratesofinletandoutletpressureincreased,theincipientcavitationindexexhibitedatendencytodecrease,whereasthefinalcavitationindexatendencytoincreaseunderallgeometricalparameters.Astheabsolutevaluesofthevariationratesofinletandoutletpressurefurtherincreased,thehysteresisbetweentheincipientandfinalcavitationindiceswouldbecomelargerthaneverforeachcombinationofthevalveandvalveseat.
Ishiharaetal.[8]studiedoilflowunsteadinesseffectoncavitationphenomenaatsharp-edgedorifices.Therateofpressuredropacrosstheorificewaskeptconstant,andcavitationincipienceandfinalewererecordedbyusingscatteredlaserbeamsshowingthat(a)thereexistedtwotypesofcavitation,namely,gaseouscavitationandvapourouscavitation,and(b)cavitationincipienceandfinalevarie
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- 外文 翻译 关于 二级 液压 节流 汽蚀 研究
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