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激光同轴送粉喷嘴是激光直接制造系统中核心部件之一,喷嘴的保护气体流场对金属粉末的流动和零件材料的性能影响较大。研究应用粒子图像测速(PIV)技术测量激光同轴送粉喷嘴轴截面保护气体的流场,并对此进行了相应的计算与分析。结果表明,喷嘴三个喷口之间的壁厚对喷嘴附近的流场影响较大,促使喷嘴喷口处产生两对对称旋涡,不利于粉末的输送和聚焦。喷嘴的三个喷口的喷出气流速度一致时,速度界面的湍流扩散和动量交换较小,将产生一个有利于输送金属粉末的稳定流场。
The laser coaxial powder feeding nozzle is one of the core components in the laser direct manufacturing system. The protective gas flow field of the nozzle has a great influence on the flow of the metal powder and the performance of the part material. The flow field of shielding gas with axis cross section of laser coaxial powder feeding nozzle was measured by particle image velocimetry (PIV) technique and the corresponding calculation and analysis were carried out. The results show that the wall thickness between the three nozzles has a greater influence on the flow field near the nozzle, which causes two pairs of symmetrical vortices at the nozzle orifice, which is not conducive to the powder transportation and focusing. When the discharge velocities of the three nozzles of the nozzle are consistent, the turbulent diffusion and momentum exchange at the velocity interface are small, which will result in a stable flow field conducive to the transport of metal powder.