NUMERICAL SIMULATION OF COAX-IAL

POWDER FLOW WITH CARRYING

GAS IN LASER MANUFACTURING

JIN Xiaoshu  YANG Xichen  FENG Liwei  WANG Yunshan

(Institute of Laser Technology, Tianjin Polytechnic University, Tianjin 300160)

Abstract: Gas-solid two-phase flow theory is used to simulate the powder flow from coaxial nozzle in coaxial powder feeder system with carrying gas, which is the key technology in laser manufacturing. The concentration distributing of powder flow and powder parameters (focus distance to nozzle exit and focus radius of powder flow) varying is simulated and analyzed. The numerical simulation result is well consistent with the result of measurement by digital particle image velocimetry (DPIV). It is shown that the concentration of powder flow and powder parameters is also influenced by gas flux and feeding powder amount. It can be found that the gas flux mainly affects the powder velocity and the powder concentration or focus parameters hardly change with various gas fluxes and constant feeding powder amount. The powder concentration tends to increase with increasing powder feed amount. The focus distance and powder stream radius at the focus point also increase and focus depth decreases with increasing the feeding powder. The powder flow simple model is also presented. The conclusion will benefit for coaxial nozzle designing and performance improving.

Key words: Laser manufacturing Coaxial powder feeding Gas-solid two-phase flow Numerical simulation

CLC No: TN49 TG665

国家自然科学基金(60478004)和天津市科委重点攻关项目(033188011)资助项目. Received 20060628, received in revised form 20061226