Analysis of magnetohydrodynamic control of scramjet inlets

Magnetohydrodynamic (MHD) control of forebody flow compression and air mass capture in scramjet inlets is analyzed for flight at Mach 5-10. Because of the low static temperature, nonequilibrium electrical conductivity is created by electron beams injected into the gas along magnetic field lines. Two-dimensional inviscid steady-state flow equations are solved jointly with equations describing electron-beam-induced ionization profiles, plasma kinetics, and MHD effects. Among several scenarios considered, the scenario with an MHD accelerator has only disadvantages. A modest increase in mass capture can in principle be accomplished with a Faraday MHD generator, if the magnetic field has components both parallel and orthogonal to the flow. The principal focus is on MHD inlet control at flight Mach numbers higher than the design value. The shocks that would otherwise enter the inlet can be moved back to the cowl lip by placing an MHD generator at one of the compression ramps. Analysis shows that the best performance of such a device is achieved with a very short MHD region placed as far upstream (close to the vehicle nose) as possible, in conjunction with a high-current ionizing electron beam. An MHD energy bypass scenario with on-ramp MHD generator for inlet control is briefly discussed.