Sprays formed by flashing liquid jets

Abstract

Liquids forced from a high-pressure zone into a low-pressure zone often cross the equilibrium pressure for the liquid temperature and disintegrate into a spray by partial evolution of vapor. The ordinary aerosol dispenser is a common example of this operation, and flash boiling is another. This paper reports on a study of the sprays formed by such a process and of the mechanism of spray formation. Sprays from water and Freon-11 jets were analyzed for drop sizes, drop velocities, and spray patterns. The breakup mechanism was analyzed and data presented to show some of the controlling factors. A critical superheat was found, above which the jet of liquid is shattered by rapid bubble growth within it. The bubble-growth rate was correlated with the Weber number, and a critical value of the Weber number was found to be 12.5 for low-viscosity liquids. The mean drop size was also correlated with Weber number and degree of superheat. The spray from rough orifices and sharp-edged orifices was compared with sprays produced from cold liquids by other techniques and was found to be comparable in all respects except temperature.