在同轴送粉激光熔覆过程中，粉末流是影响熔覆质量的重要因素。为了提高粉末流的汇聚性，考察粉末性质对粉末流场的影响，建立了同轴送粉激光熔覆粉末流数值模型。模拟计算了NiCoCrAlY、ZrO2、W三种典型粉末的粉末流形貌，并进行了粉末流的验证实验，实验结果与计算结果趋势吻合，说明模型具备合理性与可靠性。基于该模型，深入研究了粉末粒径、形状、密度和碰撞弹性恢复系数对粉末流汇聚的影响规律，在特定送粉工艺参数下，在粉末粒径增大时，汇聚焦距减小，汇聚浓度在一定粒径范围内达到最大值；在粉末形状系数或者密度增大时，汇聚焦距减小、汇聚浓度增大；在粉末颗粒的恢复系数减小时，汇聚焦距与汇聚浓度都增大。

The powder stream has an important influence on the quality of coating in coaxial laser cladding. In order to improve the convergence of powder stream, a numerical model of powder stream in coaxial laser cladding is developed based on a given coaxial nozzle. Simulations of three kinds of powder stream, including NiCoCrAlY, ZrO2 ceramic powder and W powder, are calculated and validated by the experimental results. The effect of powder properties, including particle diameter, shape, density and restitution coefficient, on the convergence of powder stream is investigated. According to the calculated results with the same powder feeding parameters, as the particle diameter increases, the powder flow focal distance decreases, and the powder concentration reaches a maximum within some particle diameter scale. The powder concentration gets bigger and the powder flow focal distance becomes shorter with the powder shape factor or powder density increasing. As restitution coefficient decreases, both powder flow distance and powder concentration increase.