The Scramjet Engine: Basic and Combined Cycles

Abstract The supersonic‐combustion ramjet (scramjet) is a cycle similar to the basic ramjet with the exception that the airflow remains, at least in certain engine regions, supersonic. The short residence time of the order of milliseconds for a full size engine, imposes severe technological requirements for fuel injection, mixing, and combustion to efficiently release heat and produce thrust. The engine is suitable for flight in excess of Mach 6 when due to the low angle of the ensuing shock waves, the engine becomes highly integrated with the vehicle. The following broadly describes the operation of the scramjet engine and the differences between this and the subsonic ramjet device. Given the range of flight speeds travelled by a hypersonic vehicle, the scramjet will operate along other cycles in a closely couple fashion; several combined cycled concepts are also described.