Thermal Effect of Sliding Electrical Contact in Electromagnetic Railgun
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摘要: 为了更准确地反映滑动电接触面的温升过程，建立了电磁轨道炮高速滑动条件下非理想电接触的计算模型，采用有限差分法，对接触电阻热效应进行了计算。计算结果表明：非理想电接触的表面温升明显高于理想接触，接触电阻层的厚度越大，电接触面的温升越快；由于速度趋肤效应的影响，接触电阻热的作用范围主要集中在接触面尾部区域；材料的热导率及输入电流的波形均对接触面温度峰值有重要的影响。研究结果为预测接触表面的材料状态，进而预测接触转捩的发生提供了理论依据。Abstract: In order to reflect the temperature rise process on the sliding electrical contact interface exactly, a numerical model of imperfect electrical contact (ImPEC) during hypervelocity sliding in electromagnetic railgun is developed.The model is implemented with finite difference method, and the thermal effect of contact resistance is simulated.The results show that more heat is generated on the contact interface due to the ImPEC.With the increasing of the thickness of the contact layer, the temperature rise on the contact interface becomes higher.Due to the velocity skin effect, the heat generated by the contact resistance is mainly concentrated at the trailing region of the interface.Furthermore, the calculated temperature is significantly influenced by the thermal conductivity and the shape of the input current.The results provide a theoretical basis for estimating the material state of sliding interface and predicting the contact transition.
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图 5 电接触面的温度峰值变化曲线
Figure 5. Maximum temperature on the electrical contact interface versus time
图 6 1.0 ms时电接触表面温度沿x方向的变化曲线
Figure 6. Variation of temperature on the electrical contact interface along x direction at 1.0 ms
图 8 不同热导率条件下电接触面的温度峰值曲线
Figure 8. Variation of maximum temperature on the electrical contact interface for different thermal conductivities
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