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建立了激光熔覆中由粉嘴输出的保护气体-金属粉末两相流场计算模型,应用FLUENT软件进行计算。该模型中考虑了两相流中动量和质量的传输。分析了金属粉末流场的水平方向和中心线上的速度分布规律,以及粉嘴内外粉末流的速度矢量分布规律。计算结果表明,中心线处粉末流速度分布先呈现微小的增大减小过程,而后单调递增,大约从粉嘴下方100 mm后呈线性递增;速度水平分布先在中心线附近达到最大而后在径向距离6~11 mm区间内线性递减至零。在相同的工艺参数下,应用数字粒子图像测速(DPIV)技术对同一流场进行检测,计算值和测量值吻合较好。结果表明,所建立的保护气体-金属粉末流速度场模型是可靠的,该模型对掌握流场参数分布和进一步指导粉嘴尺寸设计有一定的参考作用。
The calculation model of the two-phase flow field of the protective gas-metal powder output from the nozzle in the laser cladding was established, and the FLUENT software was used to calculate the flow field. The model considers the transmission of momentum and mass in a two-phase flow. The distribution rule of the velocity in the horizontal direction and the center line of the metal powder flow field and the velocity vector distribution rule of the powder flow inside and outside the nozzle are analyzed. The calculation results show that the velocity distribution of the powder flow presents a slight increase and decrease at the center line, and then monotonically increases, which increases linearly from about 100 mm below the nozzle. The velocity distribution firstly reaches the maximum near the center line and then decreases gradually Decrease linearly to zero over a range of 6 to 11 mm. Under the same process parameters, DPIV technique was used to detect the same flow field, and the calculated and measured values agree well with each other. The results show that the established model of the velocity field of the protective gas-metal powder flow is reliable. The model has certain reference function for grasping the distribution of flow parameters and further guiding the design of the nozzle size.