Energy Deposition Applied to a Transverse Jet in a Supersonic Crossflow

Abstract

An experimental investigation of a sonic underexpanded jet injected normally into a Mach 2.25 crossflow is reported. The jet exit geometry was circular and was operated at a jet-to-crossflow momentum flux ratio of 1.7. The unperturbed flowfield was analyzed with schlieren imaging, particle image velocimetry velocity data, surface oil flow visualizations, and pressure-sensitive paint measurements. As a means of excitation to the flowfield, an energy pulse from a Q-switched neodymium-doped-yttrium-aluminum-garnet laser was focused in the center of the jet exit at three different vertical locations. The focused laser pulse resulted in the induced optical breakdown of air, creating a plasma to perturb the flowfield. The perturbed resulting flowfield was analyzed with schlieren photography and particle image velocimetry. Analysis of phase-averaged schlieren images suggested that the resulting blast wave from the laser pulse disrupted the structure of the barrel shock and Mach disk. The two-component velocity field data revealed that the excitation pulse also caused a perturbation to the jet-shear layer and induced the formation of vortices that convect downstream.