TiAl基合金排气阀立式离心铸造充型及凝固过程数值模拟

以N-S方程、连续性方程及Fourier导热方程为基础，结合离心力、重力及Coriolis力，在实验的基础上建立了立式离心铸造充型过程及凝固过程数学模型．并且依据此模型对TiAl基合金排气阀立式离心铸造过程温度场、流场及压力场进行了数值模拟．数值模拟结果表明，离心铸造的充型过程存在正向和反向两个充填过程，在入口处易出现卷气缺陷．凝固过程也存在正向和反向两个凝固顺序，在靠近先充填一侧易于形成偏轴线缩松缺陷．

Numerical Simulation of Mold Filling and Solidification of TiAl Base Alloy Exhaust Valve in Vertical Centrifugal Casting Process

Based on N-S function, continuity function, function of Fourier heat conduction and experiments, a mathematical model of mold filling and solidification in vertical centrifugal casting is presented by taking centrifugal force, gravity and Coriolis force into consideration. This model is further applied to numerical simulation of temperature field, flow field and pressure field of vertical centrifugal casting process of exhaust valve made of TiAl base alloy. The result of numerical simulation shows that the mold filling of vertical centrifugal casting consists of forward-direction filling and back-direction filling. Gas-holes defect easily appears at the entrance of valve. The two orders also exist in solidification proces and are major reason for formation of off-axis shrinkage nearby the side of filling first.