基于PIC/MCC方法的TIG焊接电弧氩气击穿仿真研究

Simulation of Argon Breakdown by TIG Welding Arc Based on PIC/MCC Method

基于粒子云网格算法(PIC法)与Monte Carlo碰撞模型(MCC法),从微观粒子角度建立TIG焊接电弧等离子体氩气击穿过程的三维空间仿真模型,研究击穿过程中的粒子动态分布、电势场以及稳态温度场变化规律。模拟结果表明,电子与氩粒子、铁粒子的碰撞电离过程分别维持着击穿初态和终态时期的稳定性,氩离子聚合在弧心区域,阳极板表面以铁离子为主。空间电势场随时间推进不断增大,在定常时刻,径向电势由弧心向外不断升高,轴向电势由阳极板表面向上不断减小,直至弧心区鞘层界面达到最小值,随后逐渐上升直至焊头表面,电势升至焊接电压。在电弧稳定态时,温度场呈钟罩型,弧心温度可达到22948 K,由弧心区向外,温度逐级降低。

Based on the particle cloud grid algorithm(PIC method) and Monte Carlo collision model(MCC method), a three-dimensional space simulation model of TIG welding arc plasma argon breakdown process was established from the view of micro particle point. The particle dynamic distribution, potential field and steady temperature field change rule in the breakdown process were studied. The simulation results show that the collision ionization process between electrons and argon particles, iron particles maintains the stability of the initial state and the final state of breakdown respectively.The argon ions polymerize in the arc center region, and the surface of anode plate is dominated by iron ions. The spatial potential field increases with time. At a certain time, the radial potential increases from the arc center to outward, and the axial potential decreases from the anode plate surface upward until the sheath interface in the arc center, it reaches the minimum value, then gradually rises until the surface of the welding head to the welding voltage. When the arc is stable,the temperature field presents the shape of a bell jar, and the arc core temperature can reach 22948 K. The temperature decreases gradually from the arc center area to the outside.