大气等离子喷涂流场与粒子特性分析

Analysis of flow field and particle characteristics of atmospheric plasma spraying

实验在考虑了等离子喷涂过程中颗粒所受热泳力和压力梯度力的基础上,对大气等离子喷涂过程中的流场分布以及粒子特性进行研究,得到如下结论:在纯氩工况下,大气等离子喷涂流场最高温度为14 000 K,最高速度为470 m/s。氩氢混合工况下,流场最高温度比纯氩工况下提高了30%。温度场分布并不是沿Z轴对称,而是呈驼峰分布。载气流量在5 L/min时,颗粒能够被送入等离子体射流中心,获得流场充分的动能和热能。随着载气流量增加,颗粒穿过流场。载气流量为3 L/min时,颗粒在等离子射流体上方飞行,不利于加热加速。纯氩工况下,粒子的最大速度达到271 m/s,最大温度为4 000 K。实验工况下的最佳喷涂距离为80 mm。

The thermal swimming force and pressure gradient force of particles in the process of plasma spraying were considered,and the flow field distribution and particle characteristics in the process of atmospheric plasma spraying were studied.The results show that in pure argon,the maximum temperature of atmospheric plasma spray-ing flow field is 14000 K,and the maximum velocity is 470 m/s.The maximum temperature of flow field under argon-hydrogen mixing condition is 30%higher than that under pure argon condition.The temperature field is not symmetrical along the Z axis,but humped.When the carrier gas flow rate is 5 L/min,the particles can be sent into the center of the plasma jet to obtain sufficient kinetic energy and thermal energy of the flow field.With the increase of carrier gas flow,particles pass through the flow field.When the carrier gas flow rate is 3 L/min,the particles fly above the plasma fluid,which is not conducive to heating acceleration.In pure argon,the maximum velocity of the particles reaches 271 m/s and the maximum temperature is 4000 K.In this paper,the optimal spraying distance is 80mm.