Three-dimensional simulation on performance of a nonequilibrium disk MHD generator under subsonic flow condition

The performance of a nonequilibrium disk magneto-hydrodynamic (MHD) generat or under subsonic flow condition is examined with time-dependent r-theta -z three-dimensional numerical simulation for the first time, The uniform pla sma structure and proper fluid flow are realized for the optimal working co ndition, For low-load resistance, however, the flow chokes at the throat, a nd shock waves and boundary layer separation are observed in the generator channel, For high-load resistance, on the other hand, the subsonic flow is maintained, although the boundary layer becomes considerably thick. When th e plasma with low electron temperature flows into the generator, ionization instability takes place, which markedly reduces the enthalpy extraction ra tio and isentropic efficiency. This suggests that some way to raise the ele ctron temperature in the upstream region, for example, a pre-ionization, is needed.