简介：Thispapermainlysummarizestherecentprogressesforthecavitationstudyinthehydraulicmachineryincludingturbopumps,hydroturbines,etc..Especially,thenewlydevelopednumericalmethodsforsimulatingcavitatingturbulentflowsandtheachievementswithregardtothecomplicatedflowfeaturesrevealedbyusingadvancedopticaltechniquesaswellascavitationsimulationareintroducedsoastomakeabetterunderstandingofthecavitatingflowmechanismforhydraulicmachinery.Sincecavitationinstabilitiesarealsovitalissueandratherharmfulfortheoperationsafetyofhydromachines,wepresentthe1-Danalysismethod,whichisidentifiedtobeveryusefulforengineeringapplicationsregardingthecavitatingflowsininducers,turbinedrafttubes,etc.Thoughbothcavitationandhydraulicmachineryareextensivelydiscussedinliteratures,oneshouldbeawarethatafewproblemsstillremainsandareopenforsolution,suchasthecomprehensiveunderstandingofcavitatingturbulentflowsespeciallyinsidehydroturbines,theunneglectablediscrepanciesbetweenthenumericalandexperimentaldata,etc..Tofurtherpromotethestudyofcavitationinhydraulicmachinery,someadvancedtopicssuchasaDensity-Basedsolversuitableforhighlycompressiblecavitatingturbulentflows,avirtualcavitationtunnel,etc.areaddressedforthefutureworks.

简介：Thispaperreviewsnumericalandexperimentalinvestigationsofsheet/cloudcavitationcarriedoutattheSt.AnthonyFallsLaboratoryandattwocollaboratingfacilities(VersuchsanstaltFürWasserbau,Obernach,GermanyandOsakaUniversity,Japan)formorethanadecade.Althoughsignificantadvanceshavebeenmadeintheanalysisofthisflowseveralissuesarestillunresolved.Thepurposeofthispaperistoexaminetheoverallfeaturesoftheproblem,reviewtheprogressmadetodateandsuggestavenuesfornewinvestigation.

简介：Inthispapersomediscussionsshownwhatshouldbetheconsiderablereasonsfordifficultyincomparisonbetweenresultsofcavitationtestsinvacuumtankandsomesuggestionsaregivenhowtoimprovethecavitationtestsunderaconditionofvacuumpressure.

简介：Basedontheanalysisoftheaveragedaxisymmetricturbulentflowandthemotionandgrowthofgasnucleiintheflow,thispaperpresentsamethodforpredictingcavitationin-ceptioninpipelines.MathematicmodelisproposedandthefluctuatingpressureintheflowandotherrandomfactorswithrespecttogasnucleiaretreatedusingtheMonte-Carlomethod.Sothatthebridgebetweenmacroscopicaspectofcavitationintheflowandthemicroscopiceventofindividualnucleuscavitationissetup.Numericalinvestigationandexperimnentaltestarecarriedoutfortheflowpastanorificeinauniformpipewithcircularsection.

简介：Employingtheavailabletheory,theanaloguesimulationcriterionofthecavitationisintroducedtoprovidethebastsfortheanaloguesimulationofthecavitation.

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简介：Asimulationiscarriedoutforthepressurefluctuationdrivenbythewaterhammer,basedonajointuseoftheonedimensionalmethodofcharacteristics(MOC)andthethree-dimensionalfinitevolumemethod(FVM).Thethree-dimensionalvisualizationofthecavitationinducedbythewaterhammerisimplemented,andthetemporalandspatialanalysesofextremeregionsaremade.Apracticalcaseofthewaterhammer,withtheminimumboundarypressurehigherthanthesaturatedvaporpressurecondition,issimulated.Thesimulationpredictionthatthecavitationwouldoccurinthefrontofthegasketcouldservesomeguidelinefortheoptimizationofindustrialdesigns.

简介：Theacousticperformanceofthestructureformeasuringcavitationnoiseistheoreticallyanalysed,andtwojudgingcriteriaoftheacousticperformanceofSTW（soundtransmissionwindow）arepresentedinthispaper.OneisofimpedancematchingbetweenworkingliquidandSTW:ρ1C1=ρ2C2.Theotherisofmaximumfrequency（orminimumwavelength）ofcavitationnoisespectrum:fmax≤c/60D(orλmin/D≥60).Ifeitherofthecriteriaismetreliablemeasuredresultsofcavitationnoisewillbeobtained.Thetheoreticalresultsareverifiedthroughexperi-ments.Accordingtothecriteria,thepaperanalysestheacousticperformanceofroutinelyusedplexiglassSTW.Theresultsshowthatintheresearchofclearwatercavitationtheimpedanceratio,2.18,doesnotsatisfyρ1C1=ρ2C2,andfmax≤C/60Dhardlyholdsforactualcavitationnoisespectrum.Therefore,plexiglassSTWisnotgoodenoughforsoundtransmission.Fromthispointofview,polyethyleneisbettersoundtransmissionmaterialthanplexi-glass.

简介：Theeffectofmaterialanisotropyonthebifurcationforvoidtormationinanisotropiccompressiblehyperelasticmaterialsisexamined.Numericalsolutionsareobtainedinananisotropicsphere,whosematerialistransverselyisotropicintheradialdirection.Itisshownthatthebifurcationmayoccureithertotherightortotheleft,dependingonthedegreeofmaterialanisotropy.Thedeformationandstresscontributioninthespherebeforecavitationaredifferentfromthoseaftercavitation.Thestabilityofsolutionsisdiscussedthroughacomparisonofenergy.

简介：ＶＩＳＣＯＵＳ　ＳＣＡＬＥ　ＥＦＦＥＣＴＳ　ＯＮ　ＰＲＯＰＥＬＬＥＲ　ＴＩＰ　ＶＯＲＴＥＸ　ＣＡＶＩＴＡＴＩＯＮＶＩＳＣＯＵＳＳＣＡＬＥＥＦＦＥＣＴＳＯＮＰＲＯＰＥＬＬＥＲＴＩＰＶＯＲＴＥＸＣＡＶＩＴＡＴＩＯＮ￥ＹｅＹｕａｎ－ｐｅｉ；ＬｕＦａｎｇ；Ｓ...

简介：Thepaperconcernswiththedesignphilosophy,feasibilitystudy,aswellassomepeculiarfeaturesofIWHRwatertunnelforcavitationresearch.Thehighlightsworth-mentioningarethemaximumvelocityof35m/sandReynoldsnumberof1×10~7aswellastheprovisionofaspeciallydesignedairresorber.

简介：Amulti-functionsamplingsystemhasbeensetupinShanghaiShip&ShippingResearchInstitute(SSSRI)whereatestonthefluctuatingpressureoftwopropellermodelswerecarriedout.Thispaperdealswithastudyonthetechnicalproblemsconcerningthemeasurementandanalysistechniquesinvolvedinthetest.Thesamplingandprocessingprocedureofsignalisoneofthemajorfactorsaffectingtheac-curacyandstabilityofthepredictionoffluctuatingpressureinducedbypropeller.Integral-peri-odsampling,highenoughsamplingfrequencyandsuitableresolutionmustbekeptinsamplingandprocessing.Theprocedureofsamplingandprocessingshouldbevalidatedbystandardsignalcorrespondingtothebladefrequencyofdifferentordersincomparativetests.

简介：Theinceptionoftipvortexcavitationisverysensitivetowaterquality.Inordertoquantifytheeffectofwaterqualityontheinceptionoftipvortexcavitation,wedevelopamotionmodeltodescribethemigrationandgrowthofnucleiinwater.Ananalyticalsolutionofmigrationofnucleiinavortexflowisobtainedsothatthecapturetimesofvariousnucleicanbegivenoutdirectly.Acriterionisbuilttodeterminethecriticalnucleusinacertainnucleispectradistribution.Tensilestrengthofthecriticalnucleusisusedtoquantifytheeffectofwaterqualityandcorrectthetipvortexcavitationinceptionnumber.Finallythischangeofcavitationinceptionnumberiscomparedwithexperimentalresultstovalidateourmodel.

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简介：1.INTRODUCTIONInconnectionwithexperimentalmodelinvestigationsofcavitationphenomenaatsubmergedbodiessocalledscaleeffectscanoccur.Inordertobeabletopredictthecavitationbehaviourofaprototypefrommodeltests,thesescaleeffectsmustbeknownandbetakenintoaccountbysimu-larityrelations.Inpreviousinvestigationstestbodyfamiliesofdifferentshapesandsizewereinvestigatedinwaterofdifferenttensilestrengthforcavitationinception.

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简介：Ourobjectiveisabetterunderstandingoftheroleofphysicalpropertiesofrealfluidsinthethermodynamicsofcavitationinimpurewater.Anextensiontotheclassicalhomogenousnucleationtheorysuitableformixturesispresentedinattempttoaddressthediscrepancybetweenthetheoreticalpredictionsandpracticalobservationsofcavitationratesinwateratnormaltemperatures.Theextensiontakesintoaccoutthenon-equilibrium(dissipative)effectsinvolvedinnucleiformationthroughasubstancedependentcorrectioncoefficienttobedeterminedexperimentally.Thetheoryofthermodynamicfluctuationsisappliedtoderivetheworkofformationofabubblenucleus.Thevalueofthecorrectioncoefficientisestimatedusingpreliminaryexperimentaldatafromaconvergent-divergentnozzle.Anapplicationoftheresultstothenumericalpredictionofthecavitationzonesinaradial-flowwaterpumpisshown.

简介：稳固的墙上的表成穴的开始的预言被认出了很困难，自从它被边界层流动显著地影响特征，免费原子核的人口，原子核控制了墙粗糙，在液体的溶解空气的数量等等。开始怎么被水质量和背景流动的条件影响，足够地没被弄明白特征。在这研究，高从免费原子核加速表洞的开始的观察被进行为一二维会聚--分叉的嘴流动，表洞在此就嘴喉咙下游地形成。表成穴的开始进程上的溶解空气和免费的流速度的数量的效果被检验。另外，水泡原子核密度，众所周知是为成穴开始的重要因素，被在隧道安装的过滤器消极地控制。从观察，原子核数字密度显著地影响表洞而非另外的二个参数的形成，这被证实。在与大原子核数字调节密度，表洞不形成，并且冒泡的成穴相反出现。在有小原子核数字密度的情况中，表洞从一个单个流动原子核形成并且streamwisely并且spanwisely发展。处于有中等原子核数字密度的条件，表洞也形成，但是是shorter/更狭窄的streamwisely/spanwisely，由于流动在形成的表洞附近的另外的原子核的相互作用。

简介：Themotionofaspark-inducedcavitationbubbleandanairbubbleneararigidboundaryisexperimentallystudiedbyusinghigh-speedphotography.Severaldimensionlessparametersareusedtodescribethegeometricalconfigurationofthebubble-bubble-boundaryinteraction.Thebubble-bubbleinteractioncanbeconsideredintwodifferentconditions.Thecavitationbubblewillcollapsetowardstheairbubbleiftheairbubbleisrelativelysmall,andawayfromtheairbubbleiftheairbubbleisrelativelylarge.Thetwozonesareidentifiedinthebubble-boundaryinteraction,andtheyarethedangerzoneandthesafetyzone.Therelativeposition,thebubble-boundarydistanceandthebubble-bubbledistanceplayimportantrolesinthebubble-bubble-boundaryinteraction,whichcanbeconsideredinseveralconditionsaccordingtotheresponsesofthebubbles.Airjetsarefoundtopenetrateintothecavitationbubbles.Thecavitationbubbleandtheairbubble(airjet)moveintheirownwaywithoutmixing.Themotionofacavitationbubblemaybeinfluencedbyanairbubbleand/orarigidboundary.Theinfluenceoftheairbubbleandtheinfluenceoftheboundarymaybecombined,likesomethingofavector.

简介：Forventilatedcavitatingflowsinaclosedwatertunnel,thewalleffectmayexertanimportantinfluenceoncavityshapeandhydrodynamics.AnisotropicmixturemultiphasemodelwasestablishedtostudythewalleffectbasedontheRANSequations,coupledwithanaturalcavitationmodelandtheRNGk-εturbulentmodel.ThegoverningequationswerediscretizedusingthefinitevolumemethodandsolvedbytheGauss-Seidellinearequationsolveronthebasisofasegregationalgorithm.Thealgebraicmultigridapproachwascarriedthroughtoacceleratetheconvergenceofsolution.Thesteadyventilatedcavitatingflowsinwatertunnelsofdifferentdiameterweresimulatedforaconceptualunderwatervehiclemodelwhichhadadiskcavitator.Itisfoundthatthechokedcavitationnumberderivedisclosetotheapproximatesolutionofnaturalcavitatingflowfora3-Ddisk.Thecriticalventilationratefallswithdecreasingdiameterofthewatertunnel.However,thecavitysizeanddragcoefficientarerisingwiththedecreaseintunneldiameterforthesameventilationrate,andthecavitysizewillbemuchdifferentinwatertunnelsofdifferentdiameterevenforthesameventilatedcavitationnumber.