Theoretical Performance of Frictionless Magnetohydrodynamic-Bypass Scramjets

Abstract

Theoretical performance calculation is made of a scramjet propulsion system incorporating a magnetohydrodynamic (MHD)-energy-bypass scheme. The MHD generator upstream of the combustion chamber slows down the e ow so that the Mach number at the entrance of the combustion chamber is kept below a specie ed value. The MHD accelerator downstream of the combustion chamber accelerates the e ow, expending the electrical power produced by the generator. The e ow is seeded with potassium or cesium, and theMHD devices operate as Faraday machines. Friction is neglected, and chemical equilibrium isassumed everywhere except in the nozzle downstream of the freezing point. The calculation shows that the MHD-bypass scheme can improve specie c impulse over that of a conventional scramjet at e ight speeds over 3.5 km/s. At speeds below about 6 km/s, the calculated specie c impulse can be higher than that of a typical rocket engine. Consequently, the MHD-bypass scheme can extend the operational range or improve the performance of a conventional scramjet engine.