焊接电流影响GMAW双丝焊电弧等离子体的数值模拟研究

Numerical Analysis for Effect of Welding Current on Arc Plasma in Double-Wire GMAW

基于电磁学理论和流体力学理论,建立熔化极气体保护焊(Gas metal arc welding,GMAW)双丝焊焊接电弧等离子体三维数学模型,利用流体力学软件Fluent对其进行求解。重点研究焊接电流对GMAW双丝焊电弧等离子体行为的影响规律,获得了电弧温度、电流密度、热通量、磁场分布等结果。研究发现,随着焊接电流的变化,电弧等离子体形状变化显著。随着焊接电流的增大,电弧最高温度和电弧偏转角随之增大,电流密度和工件表面热通量由双峰分布转变为单峰分布,并且热通量峰值随焊接电流的增大而增大。此外,随着焊接电流的增大,磁感应强度和磁场力随之最大,磁场分布由独立两个磁场向耦合磁场转变。为有效、定量地证明模拟结果准确性,开展焊接试验,利用高速摄像监测电弧行为,利用光谱测温测量电弧温度。结果表明模拟结果同试验结果吻合良好,研究结果为合理选择GMAW双丝焊焊接电流参数提供理论依据。

Based on fluid dynamics theory and electromagnetic theory, a three-dimensional mathematical model is developed describing arc plasma behavior in double-wire gas metal arc welding（GMAW）. With fluid dynamic software Fluent, the model is solved. The effect of welding current on arc plasma behavior is studied and the distribution of some physical quantities are completely investigated including arc temperature, current density, heat flux, magnetic flux density. The results show that the arc plasma shape changed significantly, depending on welding current. It is found that with welding current increasing, the arc inclined degree, the maximum arc temperature, peak of heat flux and magnetic flux density on base metal surface increase, and the distribution of current density and heat flux changes from double-peak to one-peak. In addition, as welding current increases, the distribution of magnetic field changes from isolated double magnetic fields to a coupling magnetic field. To validate the accuracy of simulated results, welding experiments are carried out. Arc plasma behavior is monitored by high-speed photography and arc plasma temperature is obtained by spectral measurement. Simulated results are compared with experimental ones and there is a good agreement. The research lays a theoretical foundation for properly selecting welding current in double-wire GMAW.