Direct numerical simulation of melt–gas hydrodynamic interactions during the early stage of atomisation of liquid intermetallic

Abstract

The dynamic interactions between Raney Ni–Al intermetallic melt and argon gas at the start of atomisation , near the nozzle of close-coupled gas atomiser, for the first time, are numerically investigated using a front-tracking formulation. Some key geometric parameters of a real device are used in the model in order to simulate the real atomiser. In the model predictions of gas/melt movement, the gas jets cause melt stream pinch off and force the melt stream to wet the melt nozzle tip . Meanwhile, the melt flow has a strong influence on the evolution of gas recirculation via significant feedback. The simulated evolution of the melt stream topology up to disconnection is positively supported by related experimental results. The mechanism of the stagnation point formation proves to be very different from that predicted in conventional gas-only case studies. The peak pressure along the vertical centre line significantly varies once the melt stream becomes disconnected. The pressure gradient within the melt stream in the vertical direction contributes to the aspiration pressure, which is over-ambient with the specific parameters of this paper. This is the first time that direct numerical simulation has been used to investigate the melt–gas two-fluid flow in a real gas atomiser. Besides delivering a deep insight into the physical process involved, this new model has the potential to supply industrially applicable predictions.