Structural Optimized Design of a Powder Mixer for Multi-Material Directed Energy Deposition Based on CFD-DPM

Directed energy deposition (DED) offers an unprecedentedly convenient and efficient additive manufacturing approach to novel alloy designs such as high entropy alloys. As a critical component of the novel DED system, a powder mixer to stably and uniformly mix different powders plays an important role in the DED process. In this paper, the computational fluid dynamics-discrete phase model (CFD-DPM) method was used to simulate the characteristics of the gas-solid coupled fluid inside the powder mixer. The influence of the structural details of the powder mixer on the motion characteristics of the gas-solid coupled fluid was investigated by numerical simulation. Based on the numerical simulation results, the range of parameters of critical structure such as the inlet angle, the diameter and height mixing chamber, and the height of the bottom was determined. The difference in powder mixing uniformity among different powder mixers was qualitatively analyzed through powder mixing experiments. The BSE-EDS results of mixed powder samples show that the mixer with reasonable structural parameters has better mixing uniformity. In summary, this work provides a powerful reference for the rapid optimization design of the powder mixer structure.