Surface pressure measurements in supersonic transverse injection flowfields

Pressure-sensitive paint (PSP) was used to examine the surface pressures in flowfields created by the transverse injection of air through circular and elliptic nozzles into a supersonic freestream. Four jet-to-freestream momentum flux ratios J were investigated for each nozzle. A comparison of the PSP results with conventional pressure measurements indicates good agreement between the two techniques. Results confirm that operating conditions and injector geometry significantly affect the surface pressure field around a transverse jet. Increases in J alter the wall pressure field upstream and downstream of the injector. Injector geometry strongly affects the upstream extent of the separation region and the bow shock, and the character of the wake region downstream of the jet. Also, the effective back pressures computed from the PSP data for the elliptic injector cases are significantly higher than for the circular injector cases, presenting a possible explanation for recently observed differences in transverse penetration. (Author)