Effects of Injection Angle on Atomization of Liquid Jets in Transverse Airflow

Abstract

An experimental investigation was conducted to study and characterize the effects of injection angle on the breakup processes of turbulent liquid jets in a subsonic crosse ow of air. With water as the test liquid, the injection angle, freestream Mach number, and injection velocity were varied over a wide range to provide an extensive databaseofexperimentalresults.Pulsedshadowgraphphotographywasemployedtoascertaincolumntrajectories, column fracturelocations,and near-e eld spray characteristics.Resultsindicatethat column breakup behavior can be divided into two distinct regimes: aerodynamic and nonaerodynamic. Liquid column fracture locations were found to be governed by length scales, which depend on the corresponding breakup regime. For aerodynamic breakup, the column length scale was derived from thetimescale fortheanalogous process oftheaerodynamic secondary breakup ofadroplet.Fornonaerodynamicbreakup,thecolumnlengthscalewasderivedfromthetimescale for the breakup of a turbulent liquid jet issuing into a quiescent gas. A breakup regime parameter was dee ned to determine, based on jet operating conditions, the prevalent breakup regime and, therefore, the appropriate column length scale. Liquid column trajectories were correlated with an effective jet-to-freestream momentum e ux ratio and transverse injection angle by applying a force balance and momentum analysis. Comparisons between experimental data and analytical predictions are presented and show excellent agreement in most cases.