Wall-pressure fluctuations induced by a compressible jet flow over a flat plate at different Mach numbers

Abstract: The wall-pressure fluctuations induced by a compressible subsonic jet over a flat plate are experimentally investigated. Measurements were performed in a semi-anechoic environment, where a compressible jet facility, whose nozzle diameter (D) was 12 mm, is installed. The position of the flat plate was fixed at H/D = 2, where H is the radial position of the flat plate from the jet axis. The study was carried out for several jet Mach numbers spanning the range from 0.5 to 0.9. An overall aerodynamic characterization of the plate effect on the jet plume is provided by means of Pitot tube measurements. The wall-pressure fluctuations acting on the flat plate were measured by a couple of cavity-mounted pressure transducers, providing pointwise pressure signals in the streamwise and in the spanwise directions. A statistical and spectral characterization of the wall-pressure fluctuation field is provided addressing the effect of the jet Mach number variation and of the spatial evolution along the streamwise and spanwise directions. Implications for wall-pressure fluctuations modelling are discussed by the application of the Corcos’ model. Scaling laws with respect to the different jet flow conditions for the wall-pressure spectra are finally presented.