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激光金属沉积成形过程中,送粉喷嘴结构参数一定时,载气式同轴送粉喷嘴的粉末流场主要受送粉参数影响如载气速度、送粉量。为了进一步改善现有送粉喷嘴的汇聚性和提高粉末利用率,基于固气两相流数值计算模型,应用FLUENT软件模拟两种因素对同轴送粉喷嘴粉末流场的影响。结果表明:载气流速过小则会导致粉末流汇聚焦点浓度较低;载气速度过大则焦点形状不规则,降低成形表面质量;载气流速过小或者过大都会导致粉末利用率降低。送粉量主要影响粉末流焦点中心的汇聚浓度和粉末流速度以及速度波动。数值计算结果对同轴送粉喷嘴设计和优化激光加工工艺参数具有一定的参考价值。
Laser metal deposition forming process, powder feeding nozzle structure parameters for a certain time, carrier gas coaxial powder feeding nozzle powder flow field is mainly affected by the powder feeding parameters such as carrier gas velocity, powder feeding. In order to further improve the convergence of the existing powder delivery nozzle and improve the powder utilization rate, FLUENT software was used to simulate the influence of two factors on the powder flow field of the coaxial powder delivery nozzle based on the solid-gas two-phase flow numerical model. The results show that if the carrier gas velocity is too low, the focus concentration of the powder flow will be lower; if the carrier gas velocity is too high, the shape of the focal spot will be irregular and the quality of the forming surface will be reduced; if the carrier gas velocity is too small or too large, the utilization ratio of the powder will decrease. The amount of powder feeding mainly affects the convergence concentration and the powder flow velocity as well as the velocity fluctuation in the focal point of the powder flow. Numerical results of the coaxial powder feeding nozzle design and optimization of laser processing parameters have some reference value.