遠心圧縮機の羽根付きディフューザにおける失速領域の拡大機構に関する数値解析

抄録

In a centrifugal compressor with a vane diffuser, unsteady behavior indicating the precursor phenomena of impeller and diffuser stall in the flow range where the performance curve shows a local maximum value takes place. Within the diffuser passages, five non-swirling stall regions are formed, and they slowly begin to rotate as the compressor flow rate decreases. With a further decrease in compressor flow rate, the five cells grow into one large stall cell rotating at higher speed, but the mechanism of this growth has remained largely unclear until now. In this study, therefore, a detailed numerical analysis using DES (Detached Eddy Simulation) was employed to understand the internal flow field, identify the low-speed regions occurring in the impeller and diffuser passages, and elucidate the growth and merging mechanisms of the rotating stall cells.