简介:Onthehypothesisthattheturbulentflowispracticallynotaffectedincharacterbypulsationoftheflow,theformulaforsoundpressurelevelofpulsedjetnoiseisobtainedin90°directionand1meterawayfromthenozzle.Thesteadyjetnoiseis,then,aspecialcasewhenthepulsatingfrequencyiszero.Theresultsagreewellwithexperiments.
简介:Thecharacteristicsofalaminarwalljetsubmittedtodifferentconfigurationshavebeenexperimentallyexploredinordertoobtainabetterknowledgeoftransitionmodifications,Infactdifferentparameterscanaccelerateordelaythetransitionusingasmoothorroughsurface,heatedornot,submittedtovibrationsornot.Inthisstudy,significanteffectscanbenoticed.Ithasbeenpossibletomeasurethebeginningofgrowthratesofdisturbanceamplitudeusingawindtunnelandcomparingtheresultswiththelinearstabilitytheory.
简介:Experimentswerecarriedouttoeliminatethescreechtonegeneratedfromasupersonicjet.Compressedairwaspassedthroughacircularconvergentnozzleprecededbyastraighttubeofsamediameter.Inordertoreducethejetscreechasphericalreflectorwasusedandplacedatthenozzleexit.Theplacementofthesphericalreflectoratthenozzleexitcontrolledthelocationoftheimagesourceaswellasminimizedthesoundpressureatthenozzleexit.Theweaksoundpressuredidnotexcitetheunstabledisturbanceattheexit.Thustheloopofthefeedbackmechanismcouldnotbeaccomplishedandthejetscreechwaseliminated.Thetechniqueofscreechreductionwithaflatplatewasalsoexaminedandcomparedwiththepresentmethod.Agoodandeffectiveperformanceincancelingthescreechcomponentbythenewmethodwasfoundbytheinvestigation.Experimentalresultsindicatethatthenewsystemsuppressesnotonlythescreechtonesbutalsothebroadbandnoisecomponentsandreducestheoverallnoiseofthejetflow.Thesphericalreflectorwasfoundveryeffectiveinreducingoverallsoundpressurelevelintheupstreamregionofthenozziecomparedtoaflatplate.Thepropsedsphericalreflectorcan.accordingly,protecttheupstreamnoisepropagation.
简介:Thevolumeexpansionofthestuff(e.g.tobaccostem)isofgreatimportancetoanincreaseintheproductqualityandadecreaseintheproductioncost.Thispaterputsforwardthebasicconfigurationandtheexpansionmechanismofanewtypeofjetpressurizationevaporationexpansionapparatur.Bythethermodynamiccalculationoftheapparatus,wegivevariationsinsteampressureonvariouscrosssectionsoftheflowsystemfortheapparatus,manufactureasamplemachine,andfinishruntestsofthemachine.Thetestresultsshowthattheapparatusmaymaketherelativeincreaseinfillvalueoftobaccostemhigherthan75%,andmaycausethesteamconsumptionrequiredintheexpansionprocessofeachkilogramstemtoreducedabout40%comparedwithconventionalexpansionapparatus.Additionally,theconfigurationoftheapparatusissimpleandsmall,itscostofmanufactureisverylow,andbothitsoperationandmaintenanceareextremelyconvenient.
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简介:Thetotalefficiencyofpowerplantsdependsontheenergyconversioninacombustorandaturbine.Considerablyhigherenergytransferratescanbeobtainedfromapulsedcombustion.butunsteadyflowofasinglejetcombustorreducestheturbineefficiency.Therefore.twopulsecombustorsweresetinparallelandconnectedtoasettlingchamberthatsuppliesaflowwithconstantpressuretotheturbine.Theaimofinvestigationspresentedhereisademonstrationoftechnicalfeasibilityforindustrialapplicationsandtoshowthebenefitsobtainedfromthepulsecombustors.
简介:Theeffectofnozzlegeometryonsoniclineandcharacteristicsofsupersonicairjetwasstudied.Computationalfluiddynamicswasappliedinthisstudy.Theaxisymmetricnozzlegeometriesinvestigatedweretwodifferentcontourconvergingnozzles,twodifferentconicallyconvergingsharp-edgednozzlesandasharp-edgedorifice.Theresultsshowthatthesupersonicjetstructure,soniclineandstreamlinesinsupersonicjetarestronglyinfluencedbythenozzlegeometry,andthetotalpressurelossincreaseswiththeincreaseofMachdiskdiameter.Thepresentnumericalsimulationisaneffectivetooltoevaluatecompressibleflowsinsupersonicairjet.
简介:Atheoreticalstudywasconductedtocharacterizehydraulicjumpoflaminarcircularliquidjets.Theobjectiveofthisresearchwastodeterminethejumplocationinasimpleexplicitform,Theeffectsofmanyfactorswereinvestigatedincludingnozzlediameter,jetexitpressure,nozzle-to-platespacing,jetvelocityandReynoldsnumber,ItwasfoundthatthetheoreticaldatacollapsedwellovertherangeofjetReynoldsnumber500≤Re≤1800withpreviousdata.
简介:Whenthehigh-pressuregasisexhaustedtothevacuumchamberfromthenozzle,theunderexpandedsupersonicjetcontainedwiththeMachdiskisgenerallyformed.Theeventualpurposeofthisstudyistoclarifytheunsteadyphenomenonoftheunderexpandedfreejetwhenthebackpressurecontinuouslychangeswithtime.ThecharacteristicoftheMachdiskhasbeenclarifiedinconsiderationofthediameterandpositionofitbythenumericalanalysisinthispaper.ThesonicjetoftheexitMachnumberMe=1isassumedandtheaxisymmetricconservationalequationissolvedbytheTVDmethodinthenumericalcalculation.ThediameterandpositionoftheMachdiskdifferswiththeresultsofasteadyjetandtheinfluenceonthecontinuouslychangingofthebackpressureisevidencedfromthecomparisonwiththecaseofsteadysupersonicjet.
简介:Numericalsimulationofgas-solidflowinatwo-dimensionalfluidizedbedwithaninclinedjetwasperformed.Thenumericalmodelisbasedonthetwo-fluidmodelofgasandsolidsphaseinwhichthesolidsconstitutiveequationsarebasedonthekinetictheoryofgranularflow.TheimprovedICEalgorithm,whichcanbeusedforbothlowandhigh-velocityfluidflow,wereusedtosolvethemodelequations.Themechanismofjetformationwasanalyzedusingbothnumericalsimulationsandexperiments.Theemergenceandmovementofgasbubbleswerecapturednumericallyandexperimentally.Theinfluencesofjetvelocity,nozzlediameter,nozzleinclinationandjetpositiononjetpenetrationlengthwereobtained.Asemi-empiricalexpressionwasderivedandtheparameterswerecorrelatedfromexperimentaldata.Thecorrelationequation,whichcanbeeasilyusedtoobtaintheinclinedjetpenetrationlength,wascomparedwithourexperimentaldataandpublishedcorrelationequations.
简介:Formulatedaresimplemodelsfortheflowinliquidfilm,formedbyimpingingjet,andatwo-phasedownwardflowinpipe.Themodelsarebasedonsimplifiedequationsofmass,momentumandenergy.thesolutionofsuchconservationequationsmayhaveregularpointsbelongingtooneintegralcurveonlyaswellasturningpointscanbefoundamongstthem.Whichrefertoextremevaluesintheappropriateco-ordinatesystem.Thesolutionscanalsohavesingularpointsbelongingtononeormorethanoneintegralcurve,Boththeturningandsingularpointshaveaclearphysicalmeaning.Theycouldbelinkedtocriticalflowconditionsinthepipeflowortotheso-calledhydraulicjump.Analogyexistingbetweencriticalconditionsinthepipeandtheflowofliquidfilmsformedbytheliquidjethavebeenshowninthepaper.
简介:Wepropose,inthispaper,touseseveralmultivariateanalysismethodeandanewkindofvariablestoseparatebetweenfourclassesofeventsproducedatLEP2:theeventswith2jets,3jets,4jetsandthosehavingamoreabundantjettopology(njets,n>4)Neuralnetworkhaveproventhemselvestobemoreefficientclassifierthantheothertechniques.Theefficienciesandpuritiesachievedwiththeoptimizedneuralnetworkareinaverage1to7%higherthanthoseobtaindwiththeothermethods.
简介:Inlostpaperofmagneto-hydrodynamicinstabilityanalysisofliquidmetalfreesurfacejetflow(PartⅠ),themagneto-hydrodynamicinstabilitywasanalyzedforthejetflowinatransversenon-uniformmagneticfield,BT.But,asallknown,fortherealconditionsofliquidmetallimiter-divertorplasma-facingcomponentsareintoroidalandpoloidalfields.So,wetrytoanalyzethemagneto-hydrodynamicinstabilityofthejetflow(herebyonlyforcircularshapecrosssectionjetflow)inthezoneofnon-uniformmagneticfields,