Swept shock/boundary-layer interaction control using micro-vortex generators

Abstract

Passive flow control devices, such as vortex generators (VGs), have shown to be successful in controlling flows associated with shock-wave/boundary-layer interactions. In the present work, we investigate the effectiveness of micro-VGs in controlling the interactions of the boundary layer with a swept shock wave generated by a semi-infinite fin placed in a Mach 2 freestream generated in a wind tunnel with a rectangular cross section. The strength of the interaction is varied by changing the angle of attack of the fin in the range \(\alpha = 3^\circ \)–\(15^\circ \). Arrays of micro-VGs are placed upstream of the interaction zone in two different configurations: (I) along a line perpendicular to the freestream and (II) along a line inclined to the freestream following the conical topology of the interaction zone. A parametric analysis is done for the rectangular, ramp, and Anderson-type micro-VGs for three different heights. Unsteady and time-averaged pressure measurements are done using arrays of ports spanned radially across the interaction zone. Surface flow patterns are obtained using the oil-flow visualisation technique. It is observed that VGs offer significantly better control effectiveness when placed inclined to the freestream along the interaction region. The rectangular VGs demonstrate a maximum shift (as much as \(8^\circ \)) in the upstream influence line azimuthally towards the fin resulting in a decrease in the size of the separation region. Footprints obtained from the oil-flow experiments give important signatures of the vortices that are shed from the VGs and are responsible for the flowfield distortion in the interaction zone.