WALL-PRESSURE MEASUREMENTS FOR A SONIC JET INJECTED TRANSVERSELY INTOA SUPERSONIC CROSS-FLOW

The pressure-sensitive-paint technique was used to determine the conti nuous surface-pressure held around a sonic jet injected transversely i nto 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 n u ratio, as did the size and streamwise extent of the low-pressure reg ion downstream of the injector. About the circumference of the orifice , 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 injector periphery. As a result o f these pressure measurements, the effective back pressure, which is d efined here as the circumferentially averaged wall pressure about the orifice periphery, was observed to increase weakly with increasing jet -to-crossflow momentum flux ratio over the range investigated.