VAPORIZATION OF A LIQUID-DROP SUDDENLY EXPOSED TO A HIGH-SPEED AIRSTREAM

Many studies of fragmentation of liquid drops at supersonic Mach numbe rs report the appearance of large amounts of mist. Photographs from ot her studies, which do not mention mist at all, strongly suggest that c opious amounts of mist are formed at the earliest stages of fragmentat ion. Tn this paper, we present arguments and calculations which indica te that this mist is formed from condensed vapour arising from the fla sh vaporization of the hot and low-pressure liquid on the leeside of t he drop. Low leeside pressures are produced by the rarefaction of the gas, the acceleration of the drop, and the high tensions generated by rapid stretching of the stripped liquid. The droplet temperature may r ise because of heat transfer from the hot gas to thin drop filaments, and by viscous heating due to rapid deformation.