Numerical simulation of compressible viscous MHD flows with a bi-temperature model for reducing supersonic drag of blunt bodies and scramjet inlets

The possibility of reducing supersonic drag of blunt bodies and scramjet inlets by application of a strong magnetic field on a weakly ionized flowfield is studied in this paper. Recent interest in this concept of drag reduction has been sparked by the plasma flow control studies reported in the Russian literature wherein the shock structure in a weakly ionized plasma has been shown to be weaker than that in nonionized gases at the same temperature. This concept and others for shock wave modification/dissipation in supersonic flow are currently being investigated by the U.S. Air Force under the AJAX program. In addition, MHD by-pass concepts are being evaluated to improve the efficiency and extend the range of conventional scramjet engine. The MHD by-pass scramjet includes a MHD generator to extract power from the air entering the engine, a neutron beam to control the conductivity of the flow entering the engine, a MHD accelerator in series with the MHD generator to bypass energy around the engine combustor and return the energy into the exhaust of the engine. The goal of this project is to evaluate this concept by numerical simulation. In this paper, the effect of magnetic field on a weakly ionized plasma is studied for a blunt body and a scramjet inlet moving at hypersonic speeds using the compressible viscous elctroMHD equations with a bi-temperature model. Two-dimensional elctroMHD equations in generalized coordinates with a bi-temperature model and a variable electrical conductivity model are solved using a modified Runge-Kutta time integration scheme with second-order accurate spatial discretization. A symmetric Davis-Yee Total Variation Diminishing (TVD) flux-limiter is employed to dampen the oscillations in theshock regions. Numerical simulations are performed for a 2-D scramjet inlet and compared with the 1 -D theoretical analysis of Chul Park. Numerical results show reasonably good agreement with the 1-D theoretical analysis. They also indicate the feasibility of supersonic drag reduction by application of a strong magnetic field on the surface of a body moving at supersonic speed in a weakly ionized gas.