铸件和铸型间界面传热系数的试验研究

Experimental research on heat transfer coefficient of interface between cast and mold

在铸造凝固过程的数值模拟中,铸件/铸型间的界面传热系数是非常关键的一个参数。为提高数值模拟精度,文中采用铝合金铸件设计了金属型铸造试验,考虑了铸型厚度对结果的影响,使用特制的热电偶采集了铸件内部不同位置的温度值。以此实测的温度场数据为基础,结合数值模拟技术和界面传热系数"反问题"的求法,得到界面传热系数与时间的函数关系。结果表明:铸型厚度不同会影响铸件铸型间的热流和界面传热系数的变化规律,且界面传热系数在铸件冷却中并非常数,随着凝固过程的继续而减小。最后将所得界面传热系数用于凝固过程的温度场模拟,与试验结果进行了对比分析,得到了合理的分布,说明此界面传热系数测定方法可行。

In the numerical simulation of casting solidification process,the casting/mold interfacial heat transfer coefficient is one of the most crucial parameters.In order to improve the accuracy of numerical simulation,the aluminum alloy metal mould casting experiments were designed.By taking into account the results of the thickness of the mold,a special thermocouple was used to collect temperatures at different locations during the casting.Based on the measured temperature field data,combined with numerical simulation technology and the method of inverse problem with the interfacial heat transfer coefficient to receive a function of the interfacial heat transfer coefficient with time.The results show that different thickness of mold will affect the law of the heat flux and the heat transfer coefficient at metal/mold interface,and the interfacial heat transfer coefficient which decreases with the solidification process continuing is not a constant during cooling.After that,the interfacial heat transfer coefficient is used to simulate the temperature field of solidification process.And the simulated results was compared with the tested comes to a reasonable distribution which also proves the feasibility of determination of the interfacial heat transfer coefficient.