矩形冷坩埚定向凝固过程中钛铝熔体的流场数值计算

摘要

Numerical investigations on the flow field in Ti-A1 melt during rectangular cold crucible directional solidification were carried out.Combined with the experimental results,3-D finite element models for calculating flow field inside melting pool were established,the characteristics of the flow under different power parameters were further studied.Numerical calculation results show that there is a complex circular flow in the melt,a rapid horizontal flow exists on the solid/liquid interface and those flows confluence in the center of the melting pool.The flow velocity v increases with the increase of current intensity,but the flow patterns remain unchanged.When the current is 1000 A,the vmax reaches 4 mm/s and the flow on the interface achieves 3 mm/s.Flow patterns are quite different when the frequency changes from 10 kHz to 100 kHz,the mechanism of the frequency influence on the flow pattern is analyzed,and there is an optimum frequency for cold crucible directional solidification.%对矩形冷坩埚定向凝固钛铝合金熔体流场开展数值模拟研究.结合实验结果,建立熔体流场的3-D有限元模型,研究不同电源参数下熔池内流动特性.计算结果表明:熔池内存在着复杂的循环流动,在固液界面前端存在着较为强烈的径向对流,并在中部合流.熔体流动随着电流强度的增强而增强,但是宏观流动形貌并没有改变.当电流为1000A时,熔池内最大流速为4mm/s,固-液界面前端达到3mm/s.当频率从10kHz变化到100 kHz时,熔池流动形貌发生明显改变,分析其影响机制.对于冷坩埚定向凝固,存在着一个最佳频率.