Scramjet inlet control by off-body energy addition: A virtual cowl

The theory of energy addition to hypersonic airflow off the vehicle to increase air mass capture and reduce spillage in scramjet inlets at Mach numbers below the design value is explored. The heated region creates a virtual cowl and deflects flow streamlines into the inlet. Optimization studies are performed with a two-dimensional inviscid fluid code. The best location of the energy addition region is near the intersection of the nose shock of the vehicle with the continuation of the cowl line, and slightly below that line. In that case, the shock generated by the heating is close to the shock that is a reflection of the vehicle nose shock off the imaginary solid surface-extension of the cowl. Effects of the size and shape of the energy addition region on inlet performance are also studied.