Distortion Management in a Boundary Layer Ingestion Inlet Diffuser Using Hybrid Flow Control

Flow distortion in a 5% scale model of a blended-wing-body, boundary-layer-ingesting offset diffuser is mitigated at high subsonic speeds (up to M = 0.55) using integrated, hybrid actuators comprised of tandem configurations of passive (vanes) and active (synthetic jets) flow control elements. The inlet flow of the model diffuser is conditioned to simulate the inlet flow of an airborne blended-wing-body offset diffuser by implementation of a novel boundary layer fence. It is shown that flow distortion at the engine face is reduced by each of the passive and active elements, and the reduction is even more significant when both actuation approaches are implemented, concurrently, over the entire range of test Mach numbers. Hybrid actuation yields an overall distortion reduction of 35% at the design flow condition (M = 0.55) using a control system that is fail safe and does not require an external air supply.