Effects of injection angle on atomization of liquid jets in transverse airflow

An experimental investigation was conducted to study and characterize the e ffects of injection angle on the breakup processes of turbulent liquid jets in a subsonic crossflow of air. With water as the test liquid, the injecti on angle, freestream Mach number, and injection velocity were varied over a wide range to provide an extensive database of experimental results. Pulse d shadowgraph photography was employed to ascertain column trajectories, co lumn fracture locations, and near-field spray characteristics, Results indi cate that column breakup behavior can be divided into two distinct regimes: aerodynamic and nonaerodynamic, Liquid column fracture locations were foun d to he governed by length scales, which depend on the corresponding breaku p regime. For aerodynamic breakup, the column length scale was derived from the timescale for the analogous process of the aerodynamic secondary break up of a droplet. For nonaerodynamic breakup, the column length scale was de rived from the timescale for the breakup of a turbulent liquid jet issuing into a quiescent gas. A breakup regime parameter was defined to determine, based on jet operating conditions, the prevalent breakup regime and, theref ore, the appropriate column length scale. Liquid column trajectories were c orrelated with an effective jet-to-freestream momentum flux ratio and trans verse injection angle by applying a force balance and momentum analysis. Co mparisons between experimental data and analytical predictions are presente d and show excellent agreement in most cases.