Experimental investigation of an under-expanded single stream jet interacting with a tangential flat plate: Flow visualizations and wall pressure statistics

This paper is devoted to the experimental study of a circular converging nozzle in under-expanded conditions interacting with a tangential flat plate. Measurements were carried out in the semi-anechoic chamber of the Fluid Dynamic laboratory at the University Roma Tre. Wall pressure fluctuations are acquired by means of flush mounted Kulite sensors displaced at several streamwise positions. Qualitative flow visualizations are obtained as well, through the Background Oriented Schlieren technique that provides density gradient fields integrated along the optical path. A parametric study is carried out in terms of jet/plate distance and nozzle pressure ratio. The investigation provides, for the first time, a detailed characterization of the wall pressure statistics also correlating the achieved statistics with the shock cell structure.