THE UNSTEADY PRESSURE SIGNATURE OF TRANSONIC SHOCK WAVE/BOUNDARY LAYER INTERACTION

摘要

The statistics of wall pressure fluctuations beneath a turbulent boundary layer interacting with a normal shock wave are investigated exploiting a direct numerical simulation (DNS) database. In the zero-pressure-gradient region upstream of the interaction pressure statistics well compare with canonical boundary layers in terms of fluctuation intensities and frequency spectra. Pressure fluctuations attain large values across the interaction zone, with an increase of about 7 dB from the upstream level. The main effect of the interaction on the frequency spectra is to promote the low-frequency Fourier modes, and to inhibit the high-frequency ones. Excellent collapse of frequency spectra is observed past the interaction zone when data are scaled with the local boundary layer units. In this region an extended w?7/3 power-law behavior is observed, associated with the suppression of mean shear caused by the imposed adverse pressure gradient.