中文摘要：

为了得到同轴送粉激光熔覆中激光束穿过粉末流后的能量变化，研究了粉末浓度分布对激光能量的衰减作用。模拟了稳态、存在基底和熔池的情况下粉末流的空间分布，通过粉末浓度与激光能量衰减的关系，得到了任意粉末分布及激光能量分布下的衰减率。研究了基底对气流场的作用以及基底对粉末的反弹作用两种因素对粉末浓度分布的影响，并比较了平顶形光束在不同熔池尺寸和送粉率下的衰减率。结果表明，存在基底时粉末流对激光的衰减率比无基底作用时一般高2倍以上，与送粉率成正比，在熔池尺寸较小时与其大小成反比。

英文摘要：

The laser power attenuation by powder flow in coaxial laser cladding is investigated numerically and experimentally. A steady model of powder concentration distribution is developed, considering the effect of substrate on gas-flow and rebound of powder particles. The relationship between powder concentration and attenuation of laser power is analyzed. The effects of melt pool size and powder flow rate on a top hat laser beam attenuation are investigated. Results indicate that power attenuation by powder flow with the effect of substrate can be twice more than that without substrate. The attenuation is proportional to the powder flow rate and decreases with the increase of melt pool size when the pool size is small.