Control of Subsonic Separated Flow Using Low-Frequency Flow Oscillations

Incompressible gas flow past a two-dimensional backward-facing step on the surface of a flat plate is studied experimentally under conditions of controlled low-frequency forcing of the separated flow. It is found that flow oscillations whose frequency is an order of magnitude lower than the characteristic frequency of convective instability of the separated boundary layer cause significant changes in the time-averaged and fluctuating characteristics of the flow in the separation region.