Water atomisation of molten metals: a mathematical model for a water spray

In water atomization, a molten metal stream is fragmented by high-pressure water sprays by means of momentum transfer. In this work, a flat fan water spray is considered as a two-phase flow: water and a surrounding gas. An existing mathematical model for predicting the velocities of water droplets and entrained gas in a flat fan spray is improved. The total momentum flux of a spray is calculated for different spray travel distances, spray pressures and spray spreading angles, addressing the dependence of spray momentum flux on these parameters. A new quantity, the 'effective momentum flux', is introduced which also accounts for the effect of apex angle. Finally, based on the results of lab-scale water atomization experiments, a correlation is proposed for the powder mass median size versus the effective momentum flux of the water spray, consolidating the influence of spray parameters including pressure, travel distance, spreading angle and apex angle.