MODELLING OF THE KELVIN-HELMHOLTZ INSTABILITY IN LIQUID METAL ATOMISATION USING A FRONT TRACKING FORMULATION

摘要

The Kelvin-Helmholtz instability occurring at the interface of a two-fluid flow is the dominant mechanism coincident with the breakup of melt fluids during two-fluid atomisation. In this paper, the Kelvin-Helmholtz instability is modelled using a front tracking method. The complicated topology of the interface is explicitly tracked. Different material parameters, such as surface tension coefficient and density, have been altered in the simulations to reveal the nature of the breakup among different materials. The effects of the velocity difference on the characteristics of the liquid breakup is also under investigation. This research gives an insight into the fragmentation of the liquid stream undergoing a shear and can be used to give some theoretical guidance to industrial two-fluid atomisation processing. For the production of fine powders from the melt, initial predictions for successful production of a long interpenetrating finger-like wave to precede primary break-up show that the best conditions are a large surface tension coefficient, a large difference in velocity between the two fluids, and a large density difference.