切割用等离子弧的数值分析

以转移型直流电弧等离子体切割炬为研究对象,根据局部热力学平衡假设和磁流体动力学理论构建了电弧数学模型,采用数值模拟方法分析了等离子体炬内等离子体的传热和流动特性,阴极形状、锥角、内缩量和喷嘴形状对切割气流的速度和等离子温度分布的影响.并对五种常用形状阴极和两种不同内缩量的割炬内等离子流体速度场和温度场进行了比较.从数值分析的角度验证了阴极斑点较小的阴极能产生较大的焰流速度和热量,以及内缩量的增加对电弧的压缩具有显著作用.

Numerical analysis for cutting plasma arc

The transferred arc direct current plasma cutting torch was chosen as the studied object.According to the assumption of partial thermodynamic equilibrium and the theory of magnetic fluid dynamics, a mathematic model was developed.The plasma heattransferring and fluid properties were numerically simulated based on this model.The effect, which is induced by the cathode configuration and taper, the length of inside shrink and the spray nozzle, on the cutting current and the plasma temperature was demonstrated. The arc current density distribution was calculated based on the built model.The velocity field and temperature field of five sorts of shape of cathode and two sorts of length of inside-shrink were studied. Conclusion is drawn that cathode which have langer cathode spot area can produce higher velocity and temperature of plasma, and a significant effect of increasing of cathode inside shrink on the compression of arc has been proved.