关于连铸传热数学模型中等效导热系数的讨论

讨论了连铸传热数学模型中等效导热系数对模拟结果的影响，结论表明，采用等效导热系数法可以较为准确的预测铸坯表面温度及凝固终点，但等效导热系数越大，凝固前期的铸坯坯壳厚度越薄；等效导热系数的取值对铸坯两相区将产生较大影响，等效导热系数越大，某一厚度处钢液越早进入两相区，相应地，两相区厚度越大、两相区内温度梯度越小，局部凝固时间越大；采用计算获得的二次枝晶间距与实测值强制拟合的方法可以获得对流等效因子[（m）]的合理取值；对于铸机，在液相穴中强制对流区取[m＝7、]强制对流与自然对流的过渡区取[m＝5、]自然对流区取[m＝3、]静滞区取[m＝1]计算，可以获得较为准确的模拟结果。

Discussion of effective thermal conductivity in heat transfer models of continuous casting

Deals with the influence of effective thermal conductivity on the results of heat transfer models of continuous casting. Heat transfer models can predict the surface temperature and solidification end accurately， but shell thickness of the earlier stage of solidification becomes thinner when thermal conductivity is large. On the other hand， the value of thermal conductivity affects the prediction of mushy zone greatly. When the thermal conductivity is larger， the liquid steel turn into the mushy zone earlier. Hence， the thickness of mushy zone is thicker， temperature gradient in the mushy zone is smaller， and local solidification time is longer. Changing convection equivalent factor[（m）]to fit the calculated number and measured number is practicable method to determine the value of m. As to casting machine， while setting[m＝7]in the force convection area，[m＝5]in the transition region of force convection and natural convection， [m＝3]in the natural convection and[m＝1]in the stagnant region， an exact modeling result can be obtained.