Pre-breakup mechanism of free-fall nozzle in electrode induction melting gas atomization

Abstract

Based on the preparation of TC4 powder under electrode induction melting gas atomization in this study, the concept of pre-breakup in the free-fall nozzle channel is innovatively proposed. The computational fluid dynamics method was used to simulate the pre-breakup process, and the effect of initial droplet size on the pre-breakup process was investigated. The pre-breakup process of TC4 discontinuous droplets was simulated using a Eulerian-Eulerian volume of fluid multiphase model and the Reynolds stress model. In addition, the Eulerian-Lagrangian discrete phase model and the unstable breakup model were employed to simulate the entire atomization process of the discontinuous droplets and predict the size of the powder particles. Some simulation results were verified based on experimental measurements. The results exhibit that the pre-breakup process of discontinuous droplets can be mainly divided into the formation of ellipsoidal droplets, the formation of annular disk-shaped stacked droplets, the formation of disk-shaped liquid films, and the breakage of the disk-shaped liquid film. In addition, the pre-breakup of small droplets or droplets with appropriately increased size can effectively prevent the broken droplets from hitting and adhering to the inner wall surface of the nozzle channel. Finally, with the increase of initial droplet size, the atomized powder particle size becomes gradually coarse, and the powder particle size distribution becomes gradually concentrated.