Investigations on Active Drag Control on a Bluff Body with Cross-Wind

Active Drag Control using periodic compressed-air jets at the rear end of bluff bodies is one possible measure to reduce the total drag of these models. The dominating drag component of these configurations is the pressure drag resulting from the pressure loss due to the large wake. This study presents an experimental approach on Active Drag Control on an Ahmed body with a slant angle of 90 degrees. The stable periodic vortex structures induced by the slot actuators at the base influence the large recirculation region via a direct (momentum contained in the jet) and an indirect momentum transfer (from the outer flow into the wake). The effectiveness of the actuation strongly depends on the forcing intensity, the forcing frequency and the position of the actuator. For the asymmetric actuation with a cross-wind angle of 15 degrees, the optimal forcing parameters change, e. g. higher frequencies are necessary. Time-resolved PIV measurements prove the amplification of turbulent momentum exchange through the actuation.