片状偏钨极电弧特性的数值模拟

Numerical simulation of arc in sheet slanting electrode tungsten insert gas welding

基于流体力学和麦克斯韦方程组,建立片状偏钨极电弧三维数学模型,计算得到电弧温度场、流场、电场及电流密度分布.结果表明,片状偏钨极厚度方向电弧温度场、流场、电场及电流密度呈对称分布;相同焊接工艺参数下,片状偏钨极电弧最高温度、最大流速及电流密度小于圆柱钨极电弧;电流密度受片状偏钨极前端斜边引导作用和电弧惯性后拖效应的共同影响,其分布范围沿钨极宽度方向扩展,且电弧等温线在该方向上扩张;片状偏钨极前端斜边倾角的改变,会引起电流密度在钨极前端局部集中,并导致阴极下方高温区和阴极射流沿斜边偏移.

The three-dimensional quasi-steady state mathematical model of arc in sheet slanting electrode tungsten insert gas welding is presented based on the fluid dynamic equations and Maxwell equations.The distributions of temperature field,velocity field,electrical field and current density about arc in sheet slanting tungsten electrode are obtained.The results show that the temperature field,velocity field,electric field and current density of arc are symmetric in the thickness direction of sheet slanting tungsten electrode.The maximum temperature,velocity and current density of arc in sheet slanting tungsten electrode are lower than those of arc in cylinder tungsten electrode under the similar parameters.The sheet slanting tungsten electrode can change the gap width of arc discharge to lead the current density concentrate on the location with smaller gap width,whereas the current density would also flow backward along the hypotenuse of sheet slanting tungsten electrode due to that the arc lags behind sheet slanting tungsten electrode's motion,consequently the distribution range of current density and temperature field expand in width direction of sheet slanting tungsten electrode.The local extensive distribution of current density would occur with variation of tilt angle of hypotenuse of sheet slanting tungsten electrode,and this causes the shift of cathode jet and region with higher temperature near cathode.