目的 激光熔覆头与工作面和水平面均垂直是现有激光熔覆粉末输送的主要研究工况，研究垂直激光熔覆粉末流场可以弥补具有倾斜复杂表面特征、不可移动、不可转动的金属零部件修复的理论空缺，拓展增材制造金属零部件修复应用领域。方法 首先构建垂直激光熔覆四路同轴送粉三维气粉耦合模型，基于粉末汇聚焦点和气体流场分布确定基板工作高度和载气流量，然后探究最大粉末浓度、粉斑直径和模拟偏移量随送粉量变化的规律，最后采用单道激光熔覆实验验证模型的准确性，并实现熔覆形貌的预测。结果 在垂直激光熔覆下，随着送粉量的增大，粉末汇聚焦点变化不明显，均在距离喷嘴16 mm处;最大粉末浓度由9.8 kg/m³逐渐提升至19.2 kg/m³;模拟偏移量由0.23 mm逐渐提高至0.62 mm;粉斑直径在送粉电压为12~16 V时从2.8 mm缓慢增至3.2 mm，在16~20 V时从3.2急剧增至4.3 mm;最大粉末浓度、粉斑直径、模拟偏移量与单道激光熔覆层高、层宽、偏移量线性呈正相关，数值模拟预测值与熔覆实验测量值之间的平均相对误差分别为2.15%、1.67%、3.05%。结论 在垂直激光熔覆时，送粉量对粉末流场的影响显著，最大粉末浓度、模拟偏移量和粉斑直径均随着送粉量的增大而增大;垂直激光熔覆粉末流场模型准确可靠，可对熔覆形貌进行准确预测。该研究成果可为垂直激光熔覆工艺参数的选取及优化提供理论指导。

Laser cladding technology, as an advanced surface modification technology, is characterized by a small heat-affected zone, low dilution rate, and fast repair speed, which has become the main way of repairing and remanufacturing important metal parts. The main research condition for the existing laser cladding powder conveying reveals that the laser cladding head is perpendicular to both the working surface and the horizontal plane. The research on the powder flow field of vertical laser cladding can make up the theoretical gap in the repair of immovable and non-rotatable metal components with tilted and complex surface features and expand the application of metal component repair in additive manufacturing.