Control of penetration and mixing of an excited supersonic jet into a supersonic cross stream

Abstract

Rayleigh/Mie scattering (from flow-field ice crystals) was used to study mixing and penetration of a forced supersonic jet in a supersonic Mach (M)-2 cross stream. Instantaneous images—using image planes along (side-view) and normal (end-view) to the flow axis—were used to study the dynamical structures in the jet whereas ensemble images provide information regarding the jet trajectory. Standard deviation images reveal information about the large-scale mixing/entrainment. Probability density functions were used to evaluate the mixing along the time-average jet interface. Forced cases indicate the presence of periodic formation of large-scale eddies in the jet/free stream interface. The eddies were bigger in size and more convoluted in the forced cases as compared to the baseline. These provided high penetration of the jet into the free stream. Forced cases also show a larger region involved in small scale and/or bulk mixing in both the side—and end-views. Different metrics such as total area contained in the jet (A90), total area involved in fluctuations of ⩾30% within the jet boundary (Aσ,30) and the interfacial contact at the jet free stream interface (S) were used to quantify the mixing of the forced cases. Analysis of averaged and standard deviation of end-view images indicates that these parameters were higher for the forced cases as compared to the baseline case.