Abstract
The present paper proposes a method of linear stability analysis for subsonic disk MHD generators considering boundary conditions and load conditions. The flow in the MHD channel is described by the quasi-one-dimensional equations, whose variational equations describe the behavior of perturbations of the flow. The growth rate of perturbations is determined so that the boundary conditions and the load condition will be satisfied. Whether the perturbations grow or decay is judged diagrammatically in a way similar to the Nyquist's method. The stability is analyzed of a coal-fired inflow subsonic disk MHD generator of commercial scale. The linear stability analysis and time-dependent calculations show that both the inlet condition and the load condition much affect the stability of the flow. While the flow tends to be unstable when the inlet swirl ratio is fixed, it is stable under the constant current load condition or under the ohmic load condition when the inlet azimuthal velocity is held constant.
