Breakup, instabilities, and dynamics of high-speed droplet under transcritical conditions

Abstract

A droplet breakup model is developed for a single droplet introduced into transcritical and strong convective environments. The numerical model takes into account variable thermophysical properties, gas solubility in the liquid phase, and vapor–liquid interfacial thermodynamics. The influences of ambient conditions on droplet breakup characteristics are investigated. The results indicate that (1) the drag acceleration decreases slowly at first and then increases drastically with the initial droplet temperature increasing, but always increases at a constant rate with ambient pressure; (2) the pressure and the drop temperature have similar effects on the Kelvin–Helmholtz and Rayleigh–Taylor wave growth at high pressures (reduced pressure higher than 1.2) and high temperatures (reduced temperature higher than 0.7), but the impact of pressure on the wave growth is relatively stronger than that of droplet temperature at relatively low pressures (reduced pressure lower than 0.8) and low temperatures (reduced temperature lower than 0.63); (3) the temperature significantly affects the surface instability growth at high drop temperatures (reduced temperature higher than 0.7), but has no effect on the instability growth at low temperatures (reduced temperature lower than 0.63).