Wall pressure analysis and Background Oriented Schlieren visualization on jet-flat plate interaction

The interaction between a jet close to the sonic condition and a tangential flat plate was investigated. Measurements have been carried out in the semi-anechoic chamber of the Fluid Dynamic laboratory at the University Roma Tre. The converging nozzle has a conical shape and an outlet diameter of about D=12 mm Wall pressure fluctuations are acquired at axial distances ranging between 1 < x/D < 6. Measurements are repeated for two different radial positions of the flat plate(H/D = 2 and H/D = 0.75) and they are performed at M-j = 0.9 and M-j = 1 in slightly under-expanded conditions until NPR = 1.94. Fluctuating pressure data are analyzed in time and frequency domain and compared with the flow visualization images obtained through a Background Oriented Schlieren technique. The investigation leaded to deepen the phenomena underlying the interaction between the planar surface and the high-speed jet, clarifying the influence on the shock cell structure.