Numerical and experimental scientific investigation of combustion in a translating cowl dual-mode ramjet

Design of a wide range dual-mode ramjet To sustain high speed flight in the atmosphere, American, European and Russian institutes or companies have studied scramjet-powered hypersonic vehicles for over 40 years, and some other countries worldwide. Many applications can use such an airbreathing engine, theoretically from flight Mach number Mf= 2 (or less, in some extent) up to Mf=12 (or more, according to some studies and shock tunnel experiments). In a large part of the flight regime, the air-breathing mode appears to be a possible good solution for future Reusable Space Launchers (RSL). Achieving efficient supersonic combustion is not so challenging compared to be able to design a ramjet able to operate from subsonic to supersonic combustion in the same engine, for example on a flight envelope from 2 < Mf < 8 (or 10 or 12 with pure hydrogen): this engine is called dual-mode ramjet. Dual-mode ramjets have been studied to propel such TSTO (Two Stage To Orbit) or Single Stage To Orbit (SSTO) vehicles, or other kind of hypersonic vehicles. For example, in the scope of the French PREPHA program, the study of a generic SSTO vehicle led to conclusion that the best type of airbreathing engine could be the dual-mode ramjet (subsonic then supersonic combustion). Two main ways of approach are possible for the DMR: a fixed or a highly variable geometry. The propulsive performance (thrust, consumption) of the DMR have to be optimised, computed and at-best demonstrated. For a wide range, a variable geometry appears mandatory. The concept studied here is a good trade-off between complexity and performance.