中文摘要：

建立了脉冲电流下自由燃烧的TIG电弧的二维轴对称数学模型,利用FLUENT软件,通过选择合适的边界条件和强烈耦合控制方程组对脉冲TIG电弧进行了数值模拟,得到了在焊接电流周期性变化下电弧形态、电弧温度场、电弧轴线方向上的温度和速度及焊接工件表面电弧压力的变化情况;针对电弧压力,得到了不同峰值电流、占空比、脉冲频率作用下的分布情况,并分析了它们在脉冲电流作用下的周期性变化规律.分析结果表明：当脉冲电流发生突变时,它们的变化滞后于脉冲电流的变化,且从基值电流向峰值电流变化时的响应速度更快,并最终达到一个相对稳定的状态;在分析过程中电弧压力随峰值电流的增大而大幅度增大;随占空比的增大,有缓慢增大的趋势;随着脉冲频率的增加,电弧压力逐渐不能够达到稳定状态,且其最大电弧压力有减小的趋势.

英文摘要：

A two-dimensional axisymmetric model of free burning tangsten inert gas（TIG） arc under the action of pulsed current is developed.Using the FLUENT software and choosing appropriate boundary conditions and strongly coupling control equations,a pulsed TIG arc is simulated.The variations of arc form,temperature field,temperature and velocity on the arc axis and surface pressure distribution of the workpiece are obtained and analyzed in the periodic current process;under the action of different values of peak current,duty ratio and pulse frequency,the arc pressure distributions are obtained and analyzed.The results show that they lag behind the variation of pulse current,the variation from base current to peak current is faster,then eventually reaches a relativly stable state;with the increase of peak current,the arc pressure increase greatly;with the increase of duty ratio,the arc pressure increases slowly;with the increase of pulse frequency,the arc pressure cannot reach a stable state gradually,and the max arc pressure tends to decrease.