阴极边界条件对双射流电弧等离子体特性影响的二维数值模拟

Two-dimensional Modeling Concerning the Effects of the Boundary Conditions Along the Cathode Sheath-arc Column Interface on the Characteristics of the Dual-jet Arc Plasmas

在电弧等离子体的数值模拟研究中,阴极表面的温度及电流密度等参数的分布会直接影响到电弧弧柱区的等离子体特性。为了研究不同边界条件对电弧弧柱区等离子体特性的影响规律,采用双温度流体模型,通过给定阴极鞘层外缘不同的电流密度、电子及重粒子温度分布,对双射流直流电弧等离子体弧柱区的特性进行了二维数值模拟研究,并通过与实验测量结果的比较,讨论了不同边界条件的合理性。研究结果表明,在电弧弧电流及发生器几何参数不变的情况下,阴极鞘层外缘重粒子温度边界条件对计算得到的电弧弧柱区等离子体特性的影响可以忽略不计,电流密度对弧柱区等离子体流动特性有显著影响,而电子温度边界条件则对弧柱区电弧形貌及传热与流动特性均有显著的影响。

The distributions of the temperatures and the current densityies along the cathode surface can affect the characteristics of the arc column in the numerical modeling of the arc plasmas.In order to study the influences of different boundary conditions on the arc column characteristics of the plasmas,a two-dimensional modeling on the features of the dual-jet arc plasmas with different boundary conditions for the current density,electron and heavy-particle temperatures along the cathode sheath-arc column interface are conducted based on a two-temperature hydrodynamic model.The modeling results are also compared with the experimental measurements to discuss the feasibility of the different boundary conditions.The calculationed results show that,with the constant arc current and constant geometrical dimensions of the plasma generator,the influence of the heavy-particle temperature distributions along the outer edge of the cathode sheath layer on the plasma characteristics in the arc column region is negligible;the boundary condition of the current density along the outer edge of the cathode sheath has an obvious effect on the flow patterns in the arc column region;meanwhile,the electron temperature distributions along the cathode sheath-arc column interface would influence the arc shapes,and the heat transfer and the plasma flow patterns in the arc column region significantly.