Abstract

The aerodynamics of modern transport aircraft wings are characterised by the appearance of weak normal (or near-normal) shock waves, which lead to an additional drag component (wave drag) and the possibility of buffet – oscillatory shock motion caused by the interaction of regions of shock-induced and trailing-edge boundary layer separation. Both of these phenomena effectively limit the operational speed of the aircraft, and controlling them is therefore desirable. One method that has shown considerable promise is the ‘shock control bump’ (SCB). Although there have been extensive studies on SCB performance conducted in previous years, the details of the flow physics still require research to enable improved designs that are more robust to off-design conditions. The present work examines flow features of shock bumps through a combination of experimental and computational investigations, highlighting the connection between bump geometry and flow properties. The SCB is also shown to produce streamwise vortices capable of exerting a degree of direct boundary layer control, and the origin of this flow feature is investigated. This suggests the potential of the SCB of acting as a new class of ‘smart’ vortex generator that offsets the viscous penalty of vortex generation by reduction of other shock-related drag components.