High-Speed Schlieren Analysis of Retropropulsion Jet in Mach 10 Flow

Abstract

High-speed schlieren imaging of a 5-in.-diam, 70° sphere-cone model with a single centerline 15° half-angle nozzle was performed in a Mach 10 flow. Image sequences captured at 100 kHz were obtained with the nozzle plugged (fully blunted model), no nozzle flow, and with nozzle flow over a range of supply pressures. The freestream unit Reynolds number was kept constant for all runs at . Time-average information pertaining to the location, width, and stand-off distance of the bow shock, interface, terminal shock, and triple point as a function of jet pressure ratio are presented based on analysis of covariance images from each run. Measurement of jet plume boundary shape as a function of jet pressure ratio is also presented. Analyses of frequency content associated with the jet structure are shown, as are results of the proper orthogonal decomposition of these data. For all runs with nozzle flow, a dominant fundamental frequency of 2 kHz was observed. Finally, a discussion of bow shock unsteadiness resulting from interaction with freestream disturbances for the blunted and no nozzle flow is provided, as is a discussion on the formation of weak waves emanating from the bow shock resulting from this interaction.