Stability Analysis of Open-Cycle Supersonic Disk MHD Generator

Abstract

Stability of an open-cycle supersonic disk MHD generator is studied, and effects of load conditions on stabilizing the generator are investigated. The growth rate of inlet disturbances during the propagation to the exit is evaluated by means of a sensitivity analysis. The analysis shows that the growth rate (sensitivity) is greatly affected by load conditions, and that constant load current operations bring very high sensitivity. A method of linear stability analysis is proposed for supersonic disk MHD generators considering their load conditions in order to analyze insta-bility induced by load current disturbances. Whether the disturbances grow or decay is judged in a way similar to the Nyqu fist's method. The sensitivity analysis, the linear stability analysis and tine-dependent calculations show that constant load voltage operations with multiple-loading schemes axe effective to suppress instability and high sensitivity, and that series inductors do not always stabilize the generator.