Analysis of pressure pulsations on the wall in a flat diffuser channel in unseparated and separated flow regimes

The paper presents the results of experimental studies of pressure pulsations on the wall of a flat diffuser channel in unseparated and separated flow regimes. The dependences of the root-mean-square values of pressure pulsation amplitudes along the wall and the frequency responses for different flow regimes in the channel are given. It is shown that the maximum of the pulsation motion near the wall takes place in the beginning of the diffuser section and corresponds to the preseparation regime. The enhancement of the pulsating motion in the near-wall zone is related to the response of the flow to the pressure gradient, which is determined by the channel geometry, and is aimed at maintaining the initial unseparated flow in the boundary layer.