Evolution of Large-Scale Structures Generated by a Strut Injector in a Mach 2.5 Flow

Abstract

This work aimed to investigate the evolution of a counter-rotating vortex pair (CVP) in a flow-mixing configuration designed to explore the interaction of selected vortical structures. A CVP is shed from an expansion ramp mounted on a strut injector in a Mach 2.5 flow. Shear flow at the plume’s edges is due to sonic, parallel injection throughout the thin port located at the base of the ramp. The investigation was conducted in the supersonic wind tunnel at the Aerodynamics Research Center of the University of Texas at Arlington. Stereoscopic particle image velocimetry was the technique adopted to probe the resulting flowfields. A mixture of air and tracer particles (TiO2, nominal diameter 20nm) was injected at a nominal jet-to-freestream momentum flux ratio of 0.27, corresponding to a total pressure of 1atm in the injector’s plenum. Mean flowfield data were obtained at three different cross-planes (10, 16 and 32 ramp’s heights downstream of the injection point) and, at two selected streamwise planes. The dominant effect of the generated CVP (one order of magnitude stronger than the spanwise rollers) profoundly impacted the plume morphology.