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流动．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．
A three-phase flow model has been developed to simulate the solidification process of globular equiaxed grains based on the volume averaging and Eulerian-Eulerian methods. The three phases, liquid, solid and air, share a single pressure field. The basic conservation equations of mass, momentum and enthalpy, and a user defined conservation equation of grain density have been solved for each phase. The thermal and mechanical （drag force） interactions among the phases have been considered. Grain nucleation, growth rate （mass exchange）, solute partitioning at the liquid/solid interface and solute transport have also been accounted for. Due to the low density, the air phase floats always at the top region, forming a definable air/liquid melt interface, i.e. free surface. By tracking this free surface, the shrinkage cavity in an open casting system can be modeled. As the temperature and concentration dependent density and solidification shrinkage are explicitly included, the thermo-solutal convection, together with feeding flow and grain movement can be taken into account.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第6期584-590,共7页
Acta Metallurgica Sinica
基金
国家自然科学基金项目50474055
德国自然科学基金(DFG)重大项目SFB 370
辽宁省自然科学基金项目20052176资助
关键词
热溶质对流
补缩流
晶粒运动
三相流
数值建模
thermo-solutal convection, feeding flow, grain movement, three-phase flow, numerical modeling
