Influence of transition on the flow downstream of normal shock wave–boundary layer interactions

This paper reports recent work undertaken to investigate the interaction between normal shocks and laminar/transitional boundary layers. Laminar flow is desirable for its low skin friction, but problems are expected with shock interactions as the boundary layer will be prone to separation. Experiments have been performed on a flat plate to explore the fundamental interaction without complex geometries and flow fields; and on a transonic aerofoil to research the influence of the imposed pressure field. The boundary layer state does not appear to significantly affect the downstream flow development, contrary to expectations, as the laminar separation is so small. On the aerofoil, a similar result is observed, with no change in the buffet onset Mach number and little change in the wake. This implies that normal shock wave–laminar boundary layer interactions are not as detrimental as feared, and are in fact quite benign