论文部分内容阅读
建立了远场来流条件下过冷熔体球晶生长的温度场和浓度场稳态模型,分析了对流对球晶周围温度场和浓度场的影响,并以Trivedi的纯扩散球晶稳定性判据为基础,推导出远场来流条件下过冷熔体球晶生长的临界稳定性判据.研究表明:远场来流条件下,迎流面的扰动振幅增加速率明显大于背流面的扰动振幅增加速率.振幅增加速率最大值对应的扰动阶次从迎流面到背流面逐渐减小,随着球晶半径增加而增大.对流使迎流面的稳定性降低,背流面的稳定性增大.随着流速的增加,球晶的临界稳定半径减小.
The steady-state model of temperature field and concentration field of spherulites grown under far-field flow was established. The influence of convection on the temperature field and concentration field around spherulites was analyzed. The pure spherulite stability of Trivedi Based on the criterion, the critical stability criterion for the spherulites growth under over-cooled melt is deduced.The results show that under far-field flow conditions, the rate of increase of disturbing amplitude of the flow surface is obviously larger than that of the back flow surface The perturbation amplitude corresponding to the maximum rate of amplitude increase gradually decreases from the flow surface to the back surface and increases with the increase of the spherulitic radius.The convection makes the stability of the flow surface lower and the backflow As the flow rate increases, the critical stability radius of spherulites decreases.