矩形光斑是宽带激光熔覆的常用热源。根据矩形光斑扫描过的熔覆层呈现上厚下薄的“双椭圆”形状, 提出了椭圆热源模型, 在FLUENT软件平台上建立了基于椭圆热源的三维瞬态激光熔覆温度场和流场计算模型。模拟结果表明, 由于椭圆热源中间高、边缘低的热流分布特点和热量的累积效应, 温度场分布具有后拖现象, 熔池后端较宽, 中部较深。流体速度矢量在熔池中部主要分布在纵截面内, 越靠近边缘, 在横截面分量越多, 且纵截面内较大的涡流位于熔池后方。模拟的熔池整体上呈中间粗、两端细的狭长形貌, 与矩形光斑作用下的实际激光熔覆熔池形貌基本吻合。

The rectangle spot is a common heat source of broad-beam laser cladding. An ellipse heat source model is put forward according to the double elliptical coating shape with top thicker and bottom thinner. A three dimensional transient laser cladding temperaturefield and flowfield calculation model based on ellipse heat source model was established by FLUENT software. The simulation results show that the temperature field exhibits a typical dragged phenomenon with a wider end and deeper center molten pool, which was caused by the ellipse heat source and heat accumulation effects. The fluid velocity vector in the center pool was mainly distributed in longitudinal sections. The more close to the edge of the pool, the larger the velocity vector in cross sections. The larger eddy current in longitudinal sections was located at the back of the molten pool. The simulated molten pool shows an elongated morphology with a thick middle and thin ends, which was approximately agreed with the molten pool morphology of actual laser cladding by rectangle spot.