Spray Structure in Near-Injector Region of Aerated Jet in Subsonic Crossflow

Abstract

An experimental study of the breakup of an aerated liquid jet in subsonic crossflow was carried out. Digital double-pulsed holographic microscopy was used, employing a double exposure charge-coupled device sensor. The measurements include droplet locations, sizes and sphericity, and three-dimensional velocities. Droplet velocities in three dimensions were measured by tracking their displacements in the streamwise and cross-stream direction and by tracking the change in the plane of focus in the spanwise direction. The study demonstrated that digital holographic microscopy was suitable for probing the nonspherical droplets in the near-injector region. The droplet size distributions followed Simmons's universal root-normal distribution and thus could be fully described by the Sauter mean diameter alone. The distributions of the streamwise and cross-stream velocities were uniform in the near-injector region and could be characterized by the mass-average velocity except for very small and very large droplets.