双TIG电弧中氧传质行为的数值分析

Numerical Analysis of Oxygen Mass Transfer in Two-TIG Arc

建立氧在双钨极惰性气体(Tungsten inert gas,TIG)电弧中传质过程的三维稳态数学模型,研究总电流相同时,两钨极不同的电流分配条件下氧质量分数的分布。结果表明,氧在双TIG电弧中呈现不均匀分布,不同的电流分配对氧分布有显著影响。当两钨极电流不同时,从小电流钨极侧混入的氧更多的向这一侧的电弧区域外围扩散;当两钨极电流相同时,氧向电弧中心区域的扩散更加明显,浓度也更高;但在这两种情形下,氧整体上都明显的聚集于混入一侧的电弧区域。距离阳极上表面0.1mm位置处,氧的分布同样不均匀,两钨极电流不同时,氧质量分数和粒子数通量比两钨极电流相同时更低,预示着进入熔池的氧更少。

A three dimensional(3 D)mathematical model of oxygen transfer for two-tungsten inert gas(TIG)arc is developed and the oxygen mass fraction for different ratios of the electrode current is investigated.It is shown that the oxygen mass fraction distribution is quite heterogeneous,and the ratios of the two electrodes current for an equal total current has significant role on the oxygen distribution.The oxygen mixed from the torch with lower current is transported more to the periphery of the arc,provided that the electrode current is different;while the oxygen mixed from one torch is transported more to the central region of the arc,presenting higher oxygen concentration,if the electrode current is equal.As a whole,the oxygen is concentrated remarkably to the side of the arc from which it is introduced.At the position 0.1 mm above the anode,the distribution of the oxygen is non-uniform as well.As the current is different for each electrode,the oxygen mass fraction and number flux are lower than those for equal current of the electrode,predicting reduced oxygen dissolved into the weld pool in this case.