Control of Transonic Buffet by Shock Control Bumps on Wing-Body Configuration

Abstract

The aerodynamic shock buffet phenomenon limits the flight envelope of typical transonic aircraft at high Mach number or incidence. For future aircraft design, its correct prediction by numerical methods and control strategies are of great interest. In the present paper, simplified industrial applicable design guidelines for shock control bumps are summarized and assessed based on numerical (unsteady) Reynolds-averaged Navier–Stokes simulations of a wing-body configuration. The design guidelines cover both design objectives, wave drag reduction at dash flight, and buffet delay/alleviation. Three different shock control bumps have been designed: a two-dimensional bump for wave drag reduction at dash flight, a two-dimensional bump for delay of buffet onset, and a three-dimensional bump array with the intention of combining both design objectives. The two-dimensional bumps mark the maximum potential for each design objective with a drag reduction of 9 drag counts at dash flight and a delay of buffet onset by 4 lift counts. Even though the three-dimensional bump array combines both design objectives, it does not perform as well as expected due to massive crest-flow separation and a (so far) minor role of the vortical wake of three-dimensional bumps in delaying buffet onset.