Numerical simulation of powder-gas flow field of inside-beam powder feeding nozzle with changing attitude

Inside-beam powder feeding nozzle is a new laser cladding coaxial powder feeding nozzle, which has the advantages of hollow beam, good directivity, no interference and co-axis of light, powder and gas. In order to analyze the influence of nozzle's inclination angle and outer collimating gas velocity on the focusing characteristics of powder, FLUENT software was used for numerical simulation. The focusing characteristics of powder out of a single nozzle with changing attitude were analyzed in theory and verified in experiments. The results show that mass concentration distribution of powder nozzle is consistent with Gaussian distribution along the x direction and it remains constant firstly and then decreases to zero gradually along the -y direction of the symmetry axis. When the inclination angle of the head increases, the powder focusing length h decreases in the range of 11mm~17mm and the deviation Δx increases in the range of 0.0mm~0.4mm substantially. When the outer collimating gas velocity increases, the powder focusing length h increases slightly in the range of 1mm~2mm and the deviation Δx presents different trend in the range of 0.05mm~0.15mm. The experimental data and simulation results are basically consistent. The built model and the simulation results have reference value for the selection and optimization of experimental parameters.