保护气流量和弧长变化对电弧温度场与流场的影响

在建立了二维稳态自由燃烧的钨极氩弧焊电弧的轴对称模型的前提下,对不同弧长的电弧和改变保护气流量的电弧模型的温度场和流场进行计算比较.弧长增大,电弧的温度值、电弧电压和电弧轴向速度增加,弧长在8～10mm时轴向速度趋于稳定,气流质量得到了改善.适中的弧长可使阳极试板表面的热输入最大.保护气对电弧有压缩作用,使电弧温度升高.加大流量后对流散热的作用更明显,电极侧面的顺时针漩涡流被抵消和压缩,轴向速度的极大值区向着电极的方向运动,流线也变得相对整齐,但减缓了电弧在熔池表面的流速.

Effect of flow rate and arc length changes on velocity and temperature field of TIG arc

A steady two-dimensional (2D) axisymmetric model was developed in order to investigate the temperature and flow fields in a free burning TIG arc.A series of arc models were founded.The different flow and temperature fields of the arc in different flow rates and different arc lengths were calculated and compared.With the increase of arc length,the temperature of arc,the arc voltage and the flow velocity are increased.But the velocity stabilized in a certain value when the arc length is 8-10 mm.The moderate arc length can assure the arc with optimal heat input and better protection.The increased flow rate of shiel-ding gas compresses the arc and causes the energy emission to be much closer to the axis center,and the highest temperature is al-so increased.With the flow rate further increases,the energy e-mission and heat transfer increase,the highest temperature de-clines.The anticlockwise swirl streamtraces become larger as the flow rate increases and govern the arc region,thus the quality of flow protection is improved.The area of higher velocity in the arc column has left the original position and moved to the electrode.But the higher flow rate will delay the radial velocities on the an-ode.