抄録
A local linear perturbation analysis and a channel-length scale linear stability analysis are carried out for coalfired subsonic diagonal type MHD generators of commercial scale. Disturbances in subsonic flow propagate with downstream traveling waves and upstream traveling waves, and those waves reflect at inlet and exit boundaries. The local linear perturbation analysis examines the local growth rate of traveling waves which is determined by a dispersion equation. The channel-length scale linear stability analysis, which is based on the characteristic equation derived from the inlet and exit boundary conditions, judges whether the waves grow or decay during their propagation and reflection. The local linear perturbation analysis shows that a conventionally designed channel with near-sonic velocity has a large wave-growth rate and tends to be unstable. A newly designed channel with relatively low velocity has small wave-growth rates. The channel-length scale linear stability analysis indicates that disturbances in the conventionally designed channel grow during their propagation and reflection. The channel-length scale analysis also shows that the newly designed channel can be stably operated. Time-dependent calculations are carried out to verify the results obtained from the linear stability analyses.
