Surface Properties During Primary Breakup of Turbulent Liquid Jets in Still Air

Abstract

The formation of ligaments and drops at the liquid surface during primary breakup of turbulent liquid jets in still air, that is, during turbulent primary breakup, was studied experimentally using pulsed shadowgraphy and holography. Experimental conditions included round and plane (the latter actually being annular with a large aspect ratio) turbulent liquid jets in still air at normal temperature and pressure for noncavitating water and ethanol flows, long length/hydraulic-diameter (greater than 40:1) injector passages to provide fully developed turbulent pipe flow at the jet exit, jet exit Reynolds numbers of 6 x 10 3 -4.24 × 10 5 , jet exit Weber numbers of 200-300,000, and liquid/gas density ratios of 690 and 860 at conditions where direct effects of liquid viscosity were small (for example, jet exit Ohnesorge numbers were smaller than 0.0053). Measured properties included liquid surface velocities, conditions at the onset of ligament and drop formation, ligament and drop sizes along the surface, and ligament and drop velocities along the surface and rates of drop formation along the surface. Simplified phenomenological theories were used to help interpret and correlate the measurements