Space and time organisation of a shock wave/turbulent boundary layer interaction

The organisation of a shock wave boundary layer interaction is examined. Attention is focused on the range of frequencies and of space scales present in the flow, together with the onset of a three-dimensional structure of the separated flow. For this purpose, an oblique shock wave impinging on a turbulent boundary layer is investigated experimentally. The induced pressure gradient on the boundary layer is strong enough to make it locally separate, with an unsteady reflected shock. The space and time properties of the unsteadiness appearing in this flow have been investigated in the different zones of the flow, creating a problem with multiple time scales, and a three-dimensional separated zone. In particular, two vortices appear downstream of the reflected shock, with a time scale (time of rotation) of same order as the scale of the shock unsteadiness.