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1、等轴球晶凝固多相体系内热溶质对流、补缩流及晶粒运动的数值模拟I．三相流模型王同敏姚山张兴国金俊泽大连理工大学材料科学与工程学院摘要基于Eulerian-Eulerian方法和体积元平均技术，建立了模拟等轴球晶凝固过程的液、固、气三相流模型。液、固两相处理成相互分离、相互扩散的介质，气相与液、固两相只存在热量及动量的相互作用，三相（凝固前）作为自由流体共享一个统一的压力场。分别求解三相的质量、动量、溶质、热焓守恒方程；相间的热量交换和摩擦拖拽以及液、固界面上的溶质再分配和凝固潜热释放，通过定义对应守恒方程的源项和交换项而加以考虑；另外，单独求解一个晶粒密度守恒方程。晶粒的形核
2、生长（相变）也加以模型化并体现在对应的源项中，模型中所用的密度定义为溶质与温度的函数，因此可综合考虑热溶质对流、晶粒运动及凝固收缩所引起的补缩。凝固过程的体积收缩及补缩流动将体现在气/液自由表面的波动上。关键词热溶质对流，补缩流，晶粒运动，三相流，数值建模MWu,ALudwig(SimulationandModelingofMetalluricalProcesses,UniversityofLeoben,LeobenA-8700,Austria)BPustal,ABührig-PolaczekFoundryInstitute,RWTHAachenUniversityMODE
3、LLINGTHETHERMO-SOLUTALCONVECTION,SHRINKAGEFLOWANDGRAINMOVEMENTDURINGGLOBULAREQUIAXEDSOLIDIFICATIONINAMULTI-PHASESYSTEMI.THREE-PHASEMODELWANGTongmin,YAOShan,ZHANGXingguo,JINJunzeSchoolofMaterialsScienceandEngineering,LiaoningKeyLaboratoryofSpecialProcessingofRawMaterials,DalianUniversityofT
4、echnology,Dalian116024WuM,LudwigASimulationandModelingofMetalluricalProcesses,UniversityofLeoben,LeobenA-8700,AustriaPustalB,Bührig-PolaczekAFoundryInstitute,RWTHAachenUniversity,AachenD-52072,GermanyCorrespondent:WANGTongmin,Associateprofessor,Tel:(0411-84709458),E-mail:tmwang@dlut.edu.cn
5、SupportedbyCollaborativeProjectofGermanScienceFoundation(No.SFB370),andLiaoningNaturalScienceFoundation(No.20052176)ABSTRACTAthree-phaseflowmodelhasbeendevelopedtosimulateglobularequiaxedsolidificationbasedonthevolumeaveragingandEulerian-Eulerianmethods.Thethreephasesareliquid,solidandairr
6、espectivelysharingasinglepressure.Thebasicconservationequationsofmass,momentumandenthalpy,andauserdefinedconservationequationofgraindensityhavebeensolvedforeachphase.Thethermalandmechanical(dragforce)interactionsamongthephaseshavebeenconsidered.Grainnucleation,growthrate(massexchange),solu
7、tepartitioningattheliquid/solidinterfaceandsolutetransporthavealsobeenaccountedfor.Duetothelowdensity,theairphasefloatsalwaysatthetopregion,formingadefinableair/liquidmeltinterface,i.e.freesurface.Bytrackingthisfreesurface,theshrinkagecavityinanopencastingsyst
