Numerical simulation of the thermal history of droplets during multi-stage atomization

Analyses are made on the characteristics of cooling and undercooled solidification of multi-stage atomized aluminum droplets. Models are established for Newtonian cooling, highly undercooled heterogeneous nucleation and steady-state continuous growth. They are used for numerical simulation of the thermal history of the droplets and the effects of the main atomization process parameters such as the extent of superheat and the speed of the rotating disk. Results show that large undercooling occurs mainly in the later stage of multi-stage atomization while recalescence and rapid quenching take place mainly in the forced cooling stage. The undercooling and cooling rates of the droplets are primarily dependent on the droplet diameter, and the main atomization parameters have little effect on the nucleation and solidification behavior of the droplets.