Separated shock-boundary-layer interaction control using streamwise slots

Experiments have been performed to assess the potential of discretely placed arrays of streamwise slots to control a separated normal shock wave-turbulent boundary-layer interaction. The supersonic blowdown wind tunnel was operated at a Mach number of 1.5 and a freestream Reynolds number of 26 x 10(6) m(-1). At M = 1.5 slot control bifurcated the shock to give a lambda shock structure that was significantly larger than that seen without control. The effect on the shock Was fairly two-dimensional and persisted in the region between control devices, showing that three-dimensional control devices can have a global effect on the shock structure. In addition, slot control altered the nature of the separated boundary layer from a two-dimensional separation bubble to give highly three-dimensional regions of attached and separated flow. There is evidence that slot control also introduced streamwise vortices, which may help delay or prevent downstream separation.