Experimental Study of Characteristics of Boundary Layer Flows With Pressure Shielding

Abstract

In this study, boundary layer flows over a flat plate with a canopy of an array of rods are experimentally investigated with particle image velocimetry (PIV) measurements. The experiments were carried out in a liquid tunnel, where the refractive index of the transparent liquid is matched with that of transparent rods in the array. The statistics of the velocity data at multiple planes show the change of the flow patterns produced by the rod array. The pressure field was calculated from the velocity data through solving the pressure Poisson equation. The power spectral density of the pressure fluctuations, quantifying the sound pressure level, shows that the rod array causes the attenuation of the pressure fluctuations both below and above the rod array. The characteristic flow patterns altered by the rod array were examined by the dynamic mode decomposition. The uncertainty of the measurements was discussed.