电磁铸造大板坯半连铸过程温度场的数值模拟

NUMERICAL SIMULATION OF TEMPERATURE FIELD OF SEMI-CONTINUOUS CASTING OF SLAB IN EMC

Al的电磁铸造为半连续铸造过程，它的数学模型是空间非稳态非齐次热传输方程,提出并证明了以t时刻板坯占有的空间作为计算域，采用三维非稳态热传导方程，计算下一时刻（t＋△t）的温度场，并将温度场的位置随拉坯速度v的方向移动v△t，然后．将顶部空缺的v△t空间由浇注的金属熔液充满，此时的温度场即t＋△t时刻板坯行进位置的温度场.由于三维非稳态热传导方程具有稳定收敛的计算格式，所编制的软件可通用于三维非稳态热传输过程.模拟了1860mm×510mmAl合金大板坯，与文献已有的实测结果相比较，基本吻合.模拟结果表明，在板坯表面液柱高度相同的情况下．拉坯速度越大。

Electromagnetic casting (EMC) of aluminum alloys is a semi-continuous process accompanying mass-transfer. The mathematical model is the spatial non-stead non-homogeneous heat-transfer equation. In this paper, a method to simulate the actual EMC process has been proposed and verified as follows: firstly, based on the calculation space occupied by the slab at the time of t, a temperature field at the time of t + △t is calculated by use of three-dimensional non-steady heat conductivity equations; then,the position of the temperature field just calculated above shifts the distance of v△t along the direction of casting speed; lastly, a new temperature field of the slab can be obtained through filling the v△t space on the top of the slab with pouring metal. The new temperature field is just one of the slab at the time of t + △t. Due to use of a steady convergence type in the calculation of three-dimensional non-steady heat conductivity equations, the software developed on the basis of ideas aforementioned is universal to all processes of spatial non-steady mass-transfer. The calculations have been performed with the software to simulate an actual temperature field of 1860 mm× 510 mm aluminum alloy slab, and the calculated results have an agreement with the measurement results mentioned in reference. It also can be found from the calculated results that under the condition of same height of liquid metal column , the greater the casting speed is, the deeper the liquid concave is.