Modeling of the transport phenomena in GMAW using argon–helium mixtures. Part I – The arc

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1、InternationalJournalofHeatandMassTransfer53(2010)5707–5721ContentslistsavailableatScienceDirectInternationalJournalofHeatandMassTransferjournalhomepage:www.elsevier.com/locate/ijhmtModelingofthetransportphenomenainGMAWusingargon–heliummixtures.PartI–The

2、arca,bcab,⇑Z.H.Rao,J.Hu,S.M.Liao,H.L.TsaiaSchoolofEnergyScienceandEngineering,CentralSouthUniversity,Changsha410083,ChinabDepartmentofMechanicalandAerospaceEngineering,MissouriUniversityofScienceandTechnology,Rolla,MO65409,USAcDepartmentofMechanicalEngi

3、neering,UniversityofBridgeport,Bridgeport,CT06604,USAarticleinfoabstractArticlehistory:ThisarticlepresentsanumericalinvestigationonthetransienttransportphenomenainthearcwhichAvailableonline16September2010includethearcplasmagenerationandinteractionswithm

4、ovingdropletsandworkpieceforpureargonandthreeargon–heliummixtures(75%Ar+25%He,50%Ar+50%He,and25%Ar+75%He)duringthegasKeywords:metalarcwelding(GMAW)process.TheresultsindicatethatthearcsinvariousshieldinggasesbehaveGMAWverydifferentlyduetothesignificantdif

5、ferencesinthermophysicalproperties,includingtheionizationShieldinggaspotentialandtheelectricalconductivity,thermalconductivity,specificheat,andviscosityathightem-Plasmaarcperatures.Forthesameweldingpowerinput,itwasfoundtheincreaseofheliumcontentinthemixt

6、uresMetaltransferresultsin(1)thechangeofplasmaarcshapefrombell-liketocone-likeand(2)thechangeofarcpressuredistributionalongtheworkpiecesurfacefromGaussian-liketoflat-topwithdecreasingpeakvalue.Detailedexplanationstothephysicsoftheverycomplexbutinterestin

7、gtransportphenomenaaregiven.Ó2010ElsevierLtd.Allrightsreserved.1.Introductionhigherarcpowerdensityatthesamecurrentlevel.Incontrast,argonrequiresalowerarcvoltageforionization,whichfacilitatesabetterTheshieldinggascompositionisacriticalparameterinthearcst

8、artingandarcstability.HeliumisagoodconductorofthermalGMAWprocess.TheprimaryfunctionofshieldinggasinGMAWenergywithhigherthermalconductivitythanargon.However,istoprovideaprotectiveenvironmentforthemoltenmetalfromheliumismoreexpensi