简介：Inthispaperalumpedparametermodelofatwo-passgas-to-gascrossflowheatexchangerwithhighspeedairflowhasbeenpresentedfortheinvestigationofitstransientbehaviours.Theeffectsofboththechangesofinlettemperatureandflowrateonoutlettemperaturecanbepredictedwiththismodel.Thecalcuationresultsundertypicalconditionsarecomparedwithexperimentalresultsandgoodagreementsareobtained.

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简介：Inordertoidentifyheavierelements,wehavedevelopedanewlongitudinalfieldgasionizationchamber(IC)withanangleof30°ofplate(asshowninFig.1).TheICisoperatedinflowingiso-butanegasatapressureof10kPa.Aftertestingbyusinga3-componentαparticlesourceandcomparingwiththeoldlongitudinalfield

简介：Thispapergivesfourpairsofentropies(η_i,q_i)(i=1,2,3,4)totheisentropicgasdynamicsequationsρ_t+(ρu)_x=0(ρu)_t+(ρu~2+p(ρ))_x=0p(ρ)=k~2ρ~γ,1<γ<3。whenallthefunctionequationsaresatisfied

简介：Basedonthelinearanalysisofstability,adispersionequationisdeducedwhichdelineatestheevolutionofageneral3-dimensionaldisturbanceonthefreesurfaceofanincompressibleviscousliquidjetinjectedintoagaswithswirl.Here,thedimensionlessparameterJ_eisagainintroduced,inthemeantime,anotherdimensionlessparameterEcalledascirculationisalsointroducedtorepresenttherelativeswirlingintensity.Withrespecttothespatialgrowingdisturbancemode,thenumericalresultsobtainedfromsolvingthedispersionequationrevealthefollowingfacts.First,atthesamevalueofE,inpacewiththechangingofJ_e,thevariationofdisturbanceandthecriticaldisturbancemodestillkeepthesamecharacters.Second,thepresentresultsarethesameasthatofS.P.LinwhenJ_e>1;butintherangeofJ_e<1,it’snomorethecase,theswirldecreasestheaxisymmetricdisturbance,yetincreasestheasymmetricdisturbance,furthermoretheswirlmaymakethecharacterofthemostunstabledisturbancemodechanged(axisymmetricorasymmetric);theaboveactionoftheswirlbecomesmuchstrongerwhenJ_e《1.

简介：AnewlatticeBoltzmannmodelforcompressibleperfectgasispro-posed.Thenumericalexampleshowsthatitcanbeusedtosimulateshockwaveandcontactdiscontinuity.Theresultsarecomparablewiththoseobtainedbytraditionalmethods.Theratioofspecificheatsγmaybechosenaccordingtotherequirementofproblems.

简介：Highspeedexpansionflowsofpurevaporsorgas/vapormixturesareimportanttomanytechnichlapplications,e.g.tosteamturbines,jetengines,andforsafetycontrolofpressurizedpowerplants.Thesuddencoolingofthefluidflowleadstocondensationandnonequilibriumtwo-phaseflowwithinstabilitiesandperiodicshockformationatmeanfrequenciesofabout1kHz.Modellingandcontrolofthisdynamicalproblemisnotonlyimportantwithrespecttoerosion,italsomaycauseflutterexcitationandseriousdemolitionoftechnicalfacilities.Innumericalsimulations,thetimedependent2-DEulerequationscoupledtofourequationsdescribingtheprocessofhomogeneousnucleationanddropletgrowtharesolvedbyaMUSCL-typefinitevolumemethod.Theresultsarecomparedwithexperimentscarriedoutinanatmosphe\ricsupersonicwindtunnel.Byapplicationofthisnumericalmethodtoinernaltlows(nozzles)wefounddifferentmodesofinstabilitiesincludingbifurcations.Atthestabilitylimitasharpfrequencyminimumwasfoundforsymmetricoscillationsinslendernozzles.Itseparatesoscillationmodeswheretheoncomingsubsonicflowremainsunchangedfromtheoscillatorystatewhereashockmonotonicallymovesupstreamintotheoncomingflow.Fordifferentnozzleswedetectedanewunsymmetricoscillationmodewithacomplexsystemofupstreammovingobliqueshocks.Herethefrequencycurveshowsthetypicalstructureofabifurcationproblem,whichisdefinitelynotcontrolledbyviscouseffectsbutbyinstabilitiesoftheinteractionofflowandphasetransitionprocess.

简介：Afugacitymodelwasdevelopedforpredictionofmixedrefrigerantgashydratesformationconditionsbasedonthemoleculecongregationandsolutiontheories.Inthismodel,gashydrateswereregardedasnon-idealsolidsolutioncomposedofwatergroupsandguestmolecules,andtheexpressionsoffugacityofguestmoleculesinhydratephasewasproposedaccordingly.Ithasbeenshownthatthedevelopedmodelcanindicatesuccessfullytheeffectofguest-guestmoleculeinteraction.Theresultsshowedthatthemodelcandescribebetterthecharacteristicsofphaseequilibriumofmixedrefrigerantgashydratesandpredictionsareingoodagreementwithexperimentaldata.

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简介：Atheoryofnonfluidizedgas-solidsflow,whichcombinesthetheoryofmultiphaseflowwiththemechanicsofparticulatemedia,wasproposedonthebasisofunderstandingthattheparticlescontacteachother,solidsandgasareinmovement,andthedragforceontheparticlescausedbyinterstitialgasflowissimilartogravityforcehavingthepropertyofmassforce.Thenthistheorywasverifiedbyexperimentsonverticalandinclinedmovingbeds,andwasappliedtocalculationanddesignofequipmentanddeviceswithmovingbeds,suchaspneumaticmovingbedtransport,dipleg,V-value,L-valve,orificeflow,andarchingprevention.Itcanbeusedtoguidethedesignandoperationofmovingbedsandfixedbeds.

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

简介：He,CO2,O2,N2,CH4,C3H8,andt-C4H10gaspermeabilitycoefficientsanddiffusioncoefficientsofpoly（4-methylpentene-1）（PMP）withvariousdegreesofcrystallizationwereplottedagainstthedegreeofcrystallization.Theplotdemonstratedalinearrelationship.ThegaspermeabilitycoefficientanddiffusioncoefficientofpureamorphousandpurecrystallinePMPswereevaluatedbyalinearextrapolationtozeroand100%crystallinity,respectively.TherelationshipbetweenthediffusioncoefficientofcrystallinepartsofPMPandthekineticdiameterofpenetrantgaseswasdiscussed.Syndiotacticpolystyrene（SPS）couldexistasδformcrystalscomplexedwithorganicsolventssuchasbenzene,toluene,xylene,andethylbenzene.ThemesophaseofSPSispreparedbyannealingtheδformofcrystallinecomplexesatacertaintemperaturefor1h.Thedesorptionofsolventduringannealingalmostdoesnotresultinchangesofboththeconformationofbackbonechainsandthecrystallattice.Wecouldpreparethemesophasecontainingmolecularcavitieswiththesizeandshapeoftheorganicsolventmolecules.ThemesophasecouldsorbthesamesolventafterthemannerofLangmuirsorptionatlowvaporpressurerangewhilethiswouldnotbethecaseforsolventsofdifferentsizeandshape.Thissuggestsamolecularrecognitionoforganicsolvent,andmesophaseSPSmightbeusefulforseparationmembraneandadsorptivematerial.

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简介：Inthispaper,propagationofsoundinpipesundertheinfluenceofagasflowofhightemperatureisinvestigated.Theanalysisinthepa-perisbasedonthefundamentalequationsoffluidmechanics.Approxi-mateformulasofthevariationofparameters,suchasthestatictempera-ture,thelocalvelocityofsound,theflowspeedandtheMachnumber,withdistanceareobtained.Thefourparameterstransmisionmatixwhichdeterminestheacousticalcharacterofthepipeisderivedanddiscussed.Theacousticalcharacterofapulsatinggasheaterisinvestigatedexperim-entallyandtheoretically.Thetheoreticalvaluesoftheresonantfrequenciesofthedeviceareingoodagreementwiththeexperimentalresults.

简介：Antheoreticalinvestigationwasconductedtodetectthegas-solidinterfaceeffectonlaminarflowcharacteristicsforgasflowingthroughmicropassages.Inthewall-adjacentregion,thechangeinviscosityoffluidvsthedistancefromthewallsurface,asderivedfromthedkinetictheoryofgasesresultinsignificantinfluenceontheflowcharacteristicsinmicropassages.Amodelwasproposedtoaccountforthewalleffect.Analyticalexpressionsforvelocityprofilesandpressuredropwerederived,respectively,forlaminarflowofgasesinmicrotubesandinextremelynarrowparallelplaes.TheKnudsennumber,Kn,asacriterion,thattheflowcanbetreatedreasonablyasflowinmacrochannels,isdiscussed.

简介：Ageneralnumericalmethodispresentedforcalculatingsteadythree-dimensionalandtwo-phaseturbulentreactiveflowswithanonstaggeredbody-fittedcoordinatesysteminanannulargasturbinecombustorwiththedumpdiffuser.Themodifiedtwo-equationmodelandtheEDCturbulentcombustionmodelareusedforthegasphase.TheliquidphaseequationsaresolvedinaLagrangianframeofreferencebyPSICalgorithm.Theeffectofdifferentvelocityprofilesattheentryoftheprediffuseroncombustorflowcharacteristicsiscalculated.

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简介：Theneutralgaspressureindivertorchamberisaverybasicandimportantphysicsparameterbecauseitdeterminesthetemperatureofchargedparticles,thethermalfluxdensityontodivertorplates,theerosionofdivertorplates,impurityretainingandexhausting,particletransportationandconfinementperformanceofplasmaintokamaks.Therefore,thepressuremeasurementindivertorchamberistakenintoaccountinmanylargetokamaks.