Transient Analysis and Control of Scramjet Isolator Flowfields

Improving isolator performance and operability requires the development of a detailed understanding of the flow features in the isolator and combustor over a range of flow conditions, with the objective of identifying possible design modifications. The management of boundary-layer behavior, including growth, transition, separation, and reattachment, is essential for isolator performance. Modification of boundary-layer behavior and the shock system can be accomplished by incorporating either active or passive flow control. Passive methods of controlling the shock system in an isolator with a rectangular flowpath include mass removal, mass injection, and devices to energize the boundary-layer to prevent separation. While implementation of active control in a scramjet system will certainly be complex, active control of the boundary-layer does offer alternatives to broaden the operability limits of the inlet and the isolator in a fixed-geometry system.