等离子割炬中的电极冷却流场分析

Analysis on cooling flow field of electrode in plasma arc cutting torch

利用Fluent流体数值模拟软件建立了等离子割炬电极冷却流道的二维模型、对其进行仿真分析,研究电极的冷却介质流场与电极结构几何形状的关系,获得4种不同电极结构对冷却介质流场分布的影响.A型电极冷却介质存在滞止区,B型和C型电极冷却介质的流动存在回水区和死水区,D型带圆弧过渡的圆台型电极流场分布有利于电极的冷却.同时模拟了毛细管插入深度对冷却流速的影响,当毛细管插入深度与毛细管直径之比大于0.5时存在死水区,当毛细管插入深度与毛细管直径之比在0.2左右时,流场的分布有利于对电极的冷却,为等离子割炬的设计提供了依据.

Two-dimensional numerical model for the cooling channel and electrode in plasma cutting torch was established with FLUENT commercial software,the relationship between the coolant flow field and geometry structure of the electrode was analyzed and the effects of four different electrode structures on the distribution of cooling flow field were investigated.For A-type electrode,there existed a zone where the flowing speed of the coolant was zero.For B-type electrode and C-type electrode,there was a back-flowing zone and zero-speed zone.For D-type electrode,the arc transition in the cone-shaped electrode was beneficial to cooling of the electrode.Meanwhile,the effect of inserting depth of capillary tube on the cooling flow was simulated.When the ratio of inserting depth of capillary tube to the diameter of capillary tube was larger than 0.5,there existed a zero-speed zone,however,when the ratio was around 0.2,the distribution of fluid flow field was beneficial to cooling of the electrode.