Influence of cross-sectional shape on the performance of supersonic magnetohydrodynamic generator

Three-dimensional numerical simulations were performed to study the thermal and electromagnetic fluid characteristics of supersonic magnetohydrodynamic (MHD) generator under the influence of inlet cross-sectional shape, which tends to be applied to improv the performance of propulsion system of scramjet. A joint numerical procedure, composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations and an successioe over relaxation (SOR) method for solving the elliptic equation governing the electrical potential, was used in this paper. Numerical results indicate that the electromagnetic parameters, such as electric field, electric current density and Lorentz force etc., vary periodically along the electrode wall. The extreme values of the electromagnetic parameters are located at the edges of the electrodes. Due to the influence of width between the electrode pair, the subsequent current eddies and secondary flow on the cross-section substantially affect the performance of MHD generator. In case of small cross-sectional shape parameter, severe Joule heating and weak secondary flow are induced in the MHD generator, and vice versa in case of high shape parameter. Consequently, when the cross-sectional shape parameter α is 0.8, the enthalpy extraction ratio and electric efficiency of MHD generator are considerable.