Modeling of coaxial powder flow for the laser direct deposition process

The supplying powder jet conditions in a direct deposition process greatly influence the quality and property of deposition products. Coaxial powder flow provides the means of precise deposition due to its omnidirectional nature in a direct deposition process. In this paper, a comprehensive numerical model is presented to predict the whole process of coaxial powder flow. including the particle stream flow in and after the nozzle and laser-particle interaction process. By solving the coupled momentum transfer equations between the particle and gas phase while incorporating particle temperature evolution, the dynamic and thermal behavior of multi-particles in the stream is completely modeled. Calculated and measured results are well matched. The model is capable of predicting the powder stream structure and multi-particle phase change process with liquid fraction evolution throughout the entire process while considering the particle morphology and size distribution in real powder samples. (C) 2009 Elsevier Ltd. All rights reserved.