冷喷涂粒子速度影响因素的数值模拟与分析

Numerical analysis of effect of particle velocity in cold spraying

冷喷涂过程中,粒子速度直接影响冷喷涂材料改性效果。由于射流流场为超音速气固两相冲击射流,用实验方法研究粒子速度的影响因素很困难,为此通过数值模拟方法再现流场中粒子速度的变化情况。用Fluent软件以冷喷涂技术中超音速气固两相射流流场为研究对象,对于气固两相流的模拟,则采用颗粒轨道模型(欧拉-拉格朗日模型)获得粒子在射流流场的速度变化情况;分析粒径、材料、喷涂距离以及载气等因素对粒子速度的影响。进一步优化冷喷涂工艺方案,得到了粒子特性与粒子到达基板前最大速度之间的优化关系。

In cold spraying, the particle velocity makes a strong impact on the coating quality. It is difficult to observe the influence of particle velocity in experiment because the flow is a gas-particle two-phase supersonic impinging jet. Therefore, the numerical method can be used to analyze the varia- tion in particle velocity. The software Fluent was used to simulate the gas-solid two-phase flow field in cold spraying. The acceleration was computed by using the discrete phase modeling （DPM）. From the numerical results, the particle in-flight velocity was obtained. The effect of the particle diameter, the material property, the standoff distance and the gas condition on the particle impact velocity was analyzed to obtain the optimized relationship between the particle property and the highest speed of the particle which reaches the basilar plate. The technical project of the cold spray technology was further optimized.