Pressure-sensitive paint measurements of the pressure field about a sonic jet injected transversely into a Mach 1.6 freestream

This paper presents the results of an experimental investigation of the pressure field resulting from the interaction of a gaseous jet injected transversely into a supersonic freestream. A relatively new measurement technique. pressure-sensitive paint. was used to determine the continuous surface pressure. field around a sonic jet injected into a supersonic freestream of Mach 1.6. Three experimental conditions, with jet-to-crossflow momentum flux ratios of approximately 1.2. 1.7. and 2.2. were examined. The maximum static pressure upstream of the jet injection site was observed to increase with increasing momentum flux ratio, as did the size and extent of the low pressure region downstream of the injector. About the circumference of the injector, the pressure was observed to increase with increasing momentum flux ratio at the upstream edge of the jet, but was essentially independent of this ratio about the rest of the jet periphery. As a result of these pressure measurements about the jet injector, the effective back pressure, which is analogous to the pressure about a jet issuing into quiescent air, was observed to increase approximately linearly with increasing jet-to-crossflow momentum flux ratio.