洛伦兹力对自由燃烧弧和壁稳非转移弧流场的影响

通过耦合迭代求解流体力学方程和电磁场方程，数值模拟了转移式自由燃烧电弧和具有细长中间段及突扩阳极结构的壁稳式非转移直流电弧的流场，分析了洛伦兹力对这两种典型直流电弧流场的影响。结果显示:在自由燃烧电弧情况下，电流自感磁场的洛伦兹力对流场特性有显著影响，自磁压缩是约束电弧的主要机制；而在壁稳式非转移直流电弧情况下，相对于强壁面约束和气动力作用而言，洛伦兹力对流场的影响有限。特别在中间段出口以后，洛伦兹力与气动力的比值小于0.010，因此，当主要考虑壁稳式非转移直流电弧发生器出口参数时，为了提高数值模拟效率，可忽略洛伦兹力的作用。

Effects of Lorentz force on flow fields of free burning arc and wall stabilized non-transferred arc

The flow fields of two typical DC plasma arcs, namely the transferred free burning arc and the non-transferred arc were simulated by solving hydrodynamic equations and electromagnetic equations. The effects of the Lorentz force on the characteristics of the flow fields of these two typical DC plasma arcs were estimated. Results show that in the case of the free burning arc, the Lorentz force due to the current self-induced magnetic field has significant impact on the flow fields, as the self-induced magnetic compression is the main arc constraint mechanism. However, in the case of the non-transferred arc generated in a torch with long and narrow inter-electrode inserts and an abruptly expanded anode, the Lorentz force has limited impact on the flow fields of the plasma especially at the downstream of the inter-electrode inserts, compared with the strong wall constraints and relatively high aerodynamic force. This is because the ratio of the electromagnetic force to the aerodynamic force is only about 0.01 in this region. When the main consideration is outlet parameters of the wall stabilized non-transferred DC arc plasma generator, in order to improve the efficiency of the numerical simulation program, the Lorentz force could be neglected in the non-transferred arc in some cases.