简介:Thestudyofcylindricalparticulateflowshaswideindustrialapplicabilityandhencereceivedmuchattention.Thepurposeofthepresentpaperistoprovideareviewonthemotionofcylindricalparticlesinshearlayer,convergingchannelandjetflows,thedynamicofcylindricalparticlessedimentationinaNewtonianfluid,thecharacterizationofturbulentcylindricalparticulateflows,thepropertyofinteractionbetweentheparticles,thestructuralfeatureandrheologyofsuspensions,theanalysisofhydrodynamicinstabilityofcylindricalparticlesuspensions.Finally,theconcludingremarksaregiven.
简介:SHIPHYDRODYNAMICSBASICRESEARCHINTHEUNITEDSTATES¥EdwinP.Rood(MechanicsandEngergyConversion(333),OfficeofNavalResearchArlington...
简介:Thispapergivesemphasisontheresearchoftheproblemoflocalheadlossofcrossfractureflowbyalotofmodelexperiments,andatheoreticalmodeloflocalheadlossofcrossfractureflowisfoundedbyuseofthemomentumlawofwaterflow.Throughthecorrelationanalysisbetweenmodelexperimentalresultsandtheoreticalmodel,thecorrectioncoefficientoftheoreticalmodelisdefinite.Theproposedcalculationformulaoflocalheadlossofcrossfractureflowcanbeusedtoanalyzetheproblemofnetworkfractureseepage.
简介:Thepaperconcernswiththedesignphilosophy,feasibilitystudy,aswellassomepeculiarfeaturesofIWHRwatertunnelforcavitationresearch.Thehighlightsworth-mentioningarethemaximumvelocityof35m/sandReynoldsnumberof1×10~7aswellastheprovisionofaspeciallydesignedairresorber.
简介:Aseriesofprojectileandwater-tunnelexperimentswereconductedtoinvestigatetheshapecharactersofnaturalandventilatedsupercavitation.Itwasfoundthattheshapeanddimensionsofboththenaturalsupercavitationandtheventilatedsupercavitationaresimilarthroughthecomparisonofthemwhenthecavitationnumberissmallandequal,andthecontourofboththenaturalsupercavitationandtheventilatedsupercavitationcanbecalculatedeffectivelywiththeSavchenkoformula.Thegravityeffectcaninducetheasymmetryofventilatedsupercavitation,andtheasymmetryismoreapparentastheFroudenumberissmaller.Theempiricalformulaforcalculatingtheaxialdeformationofventilatedsupercavitationwascorrectedandexpandedbasedonexperimentdata.Theevolutionrulesofboththenaturalsupercavitationandtheventilatedsupercavitationweredescribed,andthevortexfrequencyofnaturalcavitationwasobtained.Inaddition,thehystereticaspectwasobservedbetweenthedevelopmentandthefallprocessofventilatedcavitation.
简介:Duringthedesignandconstructionofthedeepwateroffshorebasin,itscurrentgenerationsystemisconsideredtobeoneofthekeytechnologies.Inthisarticle,thestate-of-the-artdeepwateroffshorebasinatShanghaiJiaotongUniversitywasexaminedasacasestudy.Different3-Dnumericalmodelsofthecurrentgenerationsystemweredevelopedandcalculated.Theuniformityofflowfieldinthebasin,suchashorizontalandverticalcurrentvelocityprofiles,werecalculatedindetail.Besides,a1:10scaledmodeltestwasalsocarriedout.Thecurrentvelocitiesatdifferentlocationsinthebasinweremeasuredandcomparedwiththecalculatedresults.Itisconcludedthatsatisfactoryagreementcanberesultedbetweenthenumericalsimulationandmodeltest.Inaddition,itissuggestedthattransitionsectionsandturningvanesneedtobesetininflowandoutflowculvertstoimprovetheuniformityofflowfieldinthebasin.Andthehydraulicperformanceofthedeepwatercurrentgenerationsystemcanmeettherequirementsofmodeltestsindeepwater.
简介:BasedonGreen’stheorem,atimedomainnumericalmodelwasconstructedtosimulatewavemakingphenomenoncausedbyamovingship.Inthisarticle,theRankinesourcesanddipoleswereplacedonboundarysurfaces(i.e.,theshipsurfaceandfreesurface),andatime-steppingschemewasemployed.Itsuniquecharacteristicisthatsteadystatecanberealizedfrominitialvaluebyemployingthetime-steppingschemeandunsteadyfreesurfaceconditions.Intimedomain,iftheresultsofunsteadyflowproblemtendtodatastabilizationaftermanytimestepsofcomputation,theycouldberegardedasthedataofsteadyones.Thismodelcouldbeemployedtosteadyorunsteadyproblems.Theoreticalreasoningandcomputationalprocessofthismethodwasdescribedindetail.Thelinearandnonlinearboundaryconditionsonbodysurfacewerestudied,andtherelativemeanstorealizetheseboundaryconditionsiniterativecomputationwerealsodiscussed.SomeproperparametersaboutthemodeloftheWigleyhullweredeterminedbymanynumericaltests,andtheirinfluencesonwavemakingresistanceandwavepatternwerediscussed.Accordingtothecomparisonbetweennumericalresultsanddataavailableinrelativereferences,themethodusedinthisworkisproventobeareliablemethodintimedomain.Andthelatticereorganizationineverytimestepcomputationisafeasiblenumericalapproach.
简介:Inthispaper,astudyofthehigh-speedgasjetofarocketnozzleunderwaterwascarriedoutusingcommerciallyavailableCFDsoftwareFLUENTwithit'suser-defined-function.Thevolumeoffluidtechniquebasedonfinitevolumemethodwasadoptedtosolvethetime-dependentmultiphaseflowincludingacompressiblephase,andthePISOalgorithmwasincluded.Thecomputedresultsshowthatthisproblemwascalculatedsuccessfully.Thegasbubblebehindthenozzle,andthewavestructureexistinginhighlycompressedgasinwaterwerecapturedaccurately.
简介:Atime-domainKelvinsourcehigh-orderpanelmethodbasedonNURBSisdevelopedandappliedtosolvetheunsteadywave-makingproblems.Numericalresultsofinstantwaveresistanceandfreesurfaceelevationarepresentedandcomparedwiththeavailabyresultsbyotherauthors,forsubmergedspheroidandspherebeneaththefreesurfaceandforsurfaceshipofWigleymodelsmovingwithunsteadyspeed.Theagreementissatisfying.
简介:Thecut-offnegativepressuremethodisoneofeffectiveapproachestosolvetheseepageflowwithfreesurface.Accordingtothecharacteristicsofthismethod,however,ithasbeenfoundoutthatthedeficiencyofthealgorithmsistoeasilycauseinaccuratesimulationinthevicinityoffreesurfaceowingtothepenaltyfunctionwithonlyonecontrollingpenaltyparameter.Therefore,animprovedcut-offpressuremethodwaspresentedbyconstructingpenaltyfunctionwithtwocontrollingpenaltyparameters.Theimprovedalgorithmswereillustratedtobeabletoimprovethesimulationaccuracyandraisetheconvergencespeedthroughconsideringtheeffectsofthepartiallysaturatedorunsaturatedelementsmorereasonablyandcalculatingthenodalexternalforcesmoreaccurately.Finally,theimprovedcut-offnegativepressuremethodwasappliedtothesimulationofunsteadyseepageflowwithfreesurface,andthecorrespondingprogramcodesweredevelopedwithvalidationofsomecases.
简介:Thispaperstudieswaterandsolutetransportinsoil.ItmainlydealswiththeadsorptionbehaviorofheavymetalCd++insoilatdifferentPHvaluesandthedynamiccharac-tersofadsorptionprocessinunsaturatedstate.Throughtheoreticalanalysisandexperimentalre-search,theadsorptionisothermandtheequationsofdynamicadsorptioninsaturatedandunsatu-ratedstatesareproposed.
简介:Inthisarticle,thelowpressureaxialflowfanwithcircumferentialskewedrotorblade,includingtheradialblade,theforward-skewedbladeandthebackward-skewedblade,wasstudiedwithexperimentalmethods.Theaerodynamicperformanceoftherotorswasmeasured.Atthedesignconditionatoutletoftherotors,detailedflowmeasurementswereperformedwithafive-holeprobeandaHot-WireAnemometer(HWA).Theresultsshowthatcomparedtotheradialrotor,theforward-skewedrotordemonstratesawiderStableOperatingRange(SOR),isabletoreducethetotalpressurelossinthehubregionandmakemainloadingofbladeaccumulatinginthemid-spanregion.Thereisawiderwakeintheuppermid-spanregionoftheforward-skewedrotor.Comparedtotheradialrotor,inthebackward-skewedrotorthereishighertotalpressurelossnearthehubandshroudregionsandlowerlossinthemid-spanregion.Inaddition,thevelocitydeficitinthewakeisloweratmid-spanofthebackward-skewedrotorthantheforward-skewedrotor.