螺旋深小孔电解加工间隙多相流场特性及实验研究

摘要

For the difficult prediction and control of the forming size during electrochemical machining (ECM),the three-dimensional simulation and verification experiments of the gas-liquid two-phase turbulent flow in the inter-electrode gap are performed by using Fluent software with mixture model,extended SIMPLEC algorithm and standard k-ε turbulence model.A spiral deep small hole is used as the processing subject in ECM for simulation and experiment.The flow characteristic in the interelectrode gap is revealed.The results show that the velocity of the mixture in the inter-electrode gap has an important effect on the discharge of the dissolution products.Flow speed decreases and the machining stability becomes worse with the increase in hole depth.The gas volume fraction increases and the electrical conductivity decreases along the direction of the electrolyte flow,resulting in the non-uniform of the machining size of the workpiece.Furthermore,a back pressure on the outlet could reduce the nonuniform.The shape of cathode influences the flow-field characteristics.The ' dead zone',short circuit and spark could be avoided by properly designing the cathode shape.%针对电解加工(ECM)成形尺寸难以预测与控制问题,以螺旋深小孔ECM为研究对象,采用Mixture多相流模型、扩展的K-ε湍流模型与SIMPLEC算法,应用流体力学分析软件Fluent对ECM间隙两相流进行了数值模拟和验证性实验,揭示了ECM间隙流场的流动特性.研究结果表明:间隙流场的流速分布影响着间隙内产物的排出规律,随着孔深加大,流速沿流程逐渐减小,使得加工稳定性变差;沿电解液流程方向上间隙气泡率含量逐渐增加,致使电解液电导率逐渐降低,工件加工后尺寸前大后小,增加出口背压在一定程度上可以改善这一问题;阴极形状影响着间隙内流场的流动特性,合理的阴极形状可避免间隙流场“死水区”的形成及短路和烧伤现象发生.