Surface pressure measurements in supersonic transverse injection flowfields

Pressure sensitive paint (PSP) was used to examine the surface pressures in flow fields created by the transverse injection of air through circular an d elliptic nozzles into a supersonic freestream. Four Jet-to-freestream mom entum Aux ratios J were investigated for each nozzle. A comparison of the P SP 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 d ownstream of the injector. Injector geometry strongly affects the upstream extent of the the separation region and the bow shock, and the character of the wake region downstream of the the Jet. Also, the effective back pressu res computed from the PSP data for the elliptic injector cases are signific antly higher than for the circular injector cases, presenting a possible ex planation for recently observed differences in transverse penetration.