Three-dimensional computation of magnetohydrodynamics in a weakly ionized plasma with strong MHD interaction

A large-scale pulsed MHD generator with an MHD channel of 4.5 m, having demonstrated the maximum electric power output of 510 MW, is studied numerically with a time-dependent three-dimensional analysis. It is shown that strong oblique shock waves are generated at a connection between the nozzle and insulating walls, traveling to the channel exit. The strong oblique shock waves cause fluctuations of gasdynamic quantities along the x-direction, resulting in a slight decrease of the Faraday current density. As a result, the strong oblique shock waves deteriorate slightly the generator performance. It is also shown that a strong pseudo-shock wave with a large boundary-layer separation is induced by the strong MHD interaction under the condition of a low channel voltage. The boundary-layer separation becomes large near the anode because of the strong Lorentz force in the y-direction attributed to the large Hall current. It is also shown that the cross-sectional secondary flow attributed to the Hall current on the y–z plane is not induced under the present conditions.