Numerical simulation of plasma–fluid flow and performance in a disc MHD generator with contoured walls

Abstract

Two-dimensional large eddy simulations have been carried out in order to investigate the performance of two disc MHD generators with different disc walls cross-sectional profiles. The first disc MHD generator has been designed with a ‘typically-used’ straight disc walls profile; the second, on the other hand, presents a contoured disc walls profile. The numerical results, obtained for a set of realistic working conditions and very fine grid meshes, show that the generator with contoured walls achieves the highest generator performance, measured in terms of enthalpy extraction and isentropic efficiency, because of improvements in flow behaviour and plasma conditions. In particular, under optimum generator performance conditions, a high Mach number–low static pressure MHD flow is realized in the generator with contoured disc walls. Here, the Lorentz force is not able to significantly drag the supersonic MHD flow even if a high magnetic flux density (4–8 T) is applied. As a consequence, MHD generators with contoured disc walls could achieve the generator performance target for commercialization of MHD power generation.