Interaction between high-velocity gas and liquid in gas atomization revealed by a new coupled simulation model

Due to the high efficiency and low cost, gas atomization (GA) has been widely applied to produce metal powders. In this paper, the GA process is first modeled by combining the volume of fluid (VOF) model with dynamic adaptive mesh and the discrete phase model (DPM) to simulate the formation of the powders and the evolution of the defects. Simulation results show that the Kelvin-Helmholtz instability in the primary atomization and the membranous droplet breakup and closure in secondary atomization can form the hollow powder. While the presence of the satellite powder is caused by the collisions between the large and small droplets with different velocities. Moreover, the irregular powder is produced when the drag force is not enough to separate the droplets but deforms them. The estimated morphology and size distribution of the particles have a good agreement with the experimental ones. Finally, the possible measures to reduce the defects of the powders have been put forward based on the revealed mechanism of defect evolution. This work provides a deep simulation insight into the GA process, towards producing high-quality metal powders for additive manufacturing on a large scale.