电磁搅拌法制备半固态浆料过程电磁场、流场和温度场的数值模拟

Numerical simulation of electromagnetic field,flow field and temperature field in semi-solid slurry preparation by electromagnetic stirring

建立了铝合金半固态浆料电磁搅拌过程宏观传输物理量耦合的数学模型,采用有限元和有限差分相结合的方法实现电磁搅拌条件下电磁场、流场和温度场的耦合模拟分析,研究电磁搅拌工艺参数对流场和温度场的影响规律,并进行实验验证。结果表明:水平旋转的电磁力场在铝合金熔体内均匀分布,其方向与交变电磁场的旋转方向一致,大小则因集肤效应从边部到中心递减;熔体内速度场分布与电磁力相似,但随着搅拌时间的延长,熔体温度降低,速度不断降低;电磁搅拌条件下熔体凝固速度加快,熔体心部和边部的温度梯度变小;搅拌电流强度和频率对电磁场、速度场和温度场分布的影响非常明显。

A two-dimensional computational model coupling a macroscopic heat and fluid flow analysis with electromagnetic stirring（EMS） in semisolid slurry preparation was developed.The method combining finite element and finite difference was used to deal with coupling electromagnetic field with flow field and temperature field.The characteristics of electromagnetic field,flow field and temperature field under electromagnetic stirring were analyzed,considering the influences of the stirring current and frequency.The dynamic evolution of transport phenomena during solidification under electromagnetic stirring was presented successfully.The simulated results show that a horizontal rotational electromagnetic force with the same rotating direction with the magnetic flux density is uniformly distributed in the stirred melt,but its magnitude decreases from edge to center due to the skin effect of the induced current.The velocity field distribution is similar to the electromagnetic field,but the velocity quickly decreases with the stirring time increasing when the temperature decreases in the melt.The electromagnetic stirring accelerates the solidification rate,and the temperature difference between the melt edge and the melt center becomes small.The altering stirring current and frequency markedly influence the distribution of electromagnetic field,flow field and temperature field.