In order to study the mixing and combustion performances of magnetohydrodynamic(MHD)-bypass scramjet(AJAX)

the three-dimensional numerical methods were used for the MHD generator flow and the chemical reaction flow

respectly.The combustion entrance conditions were varied by altering the MHD conditions

the mixing efficiencies and combustion efficiencies were got.The results show that as the magnetic field strength increases or load factor decreases

the mixing efficiency is increase

the improved maximum value of mixing efficiency is 11.6%.In the front part of chamber where the thermal dissociation is not sensible

the combustion efficiency is increase;in the latter part of the chamber

while the thermal dissociation is no present

the combustion efficiency are increase

the improved maximum value of combustion efficiency is 6.5%

the combustion chamber is shorten by 25%

reduce the geometric sizes and mass of the vehicle;while the thermal dissociation is present

the combustion efficiency are reduced even lower than the no-MHD case

so it should try to avoid larger magnetic field strengths or smaller load factors to reduce the temperature of the combustion entrance

which cause the thermal dissociation reduce the combustion efficiency.