Transient Characteristics of Constant Velocity Faraday-Type MHD Generator

Abstract

Transient characteristics of an open-cycle constant velocity Faraday-type MHD generator comparable to the size of Russian U·25 (MHD Experimental Generator at the Institute for High Temperatures, Moscow) are presented. Transient responses to start-up, shutdown and load changes of a subsonic MHD generator are numerically calculated solving unsteady magnetohydrodynamic equations. Results show that the MHD generator can attain another steady state within ten times the gas residence time for most of load changes. When loads locally change, shock waves occur to cause considerable fluid property change. The most dangerous transient characteristics are due to very large transient Hall fields at the start-up, which leads to breakdown between adjacent electrodes, particularly, the down-stream region of the generator. For local short-circuiting or load changes throughout the generator, no serious problems arise except for those associated with current density increase.