Abstract: Numerical simulation results of rotating stall flow phenomenon inside a centrifugal compressor with vaneless diffuser by solving three-dimensional Reynolds averaged compressible N-S equations using commercial computational fluid dynamics (CFD) software CFX adopting RNG turbulence model are presented. For exactly simulating the rotating stall at small flow rate, the whole flow field mesh including volute is used. Firstly the steady performance curve is obtained using steady calculations and comparing with experimental results. Secondly, an air chamber model is added at the volute outlet to simulate the rotating stall flow phenomenon inside the centrifugal compressor. The centrifugal compressor internal flow fields at different times during the stall cycle at the small mass flow rate are given to observe the stall flow phenomenon. The air chamber influence on the rotating stall is also investigated. The simulation indicates the more the plenum chamber volume is, the lower the stall frequency will be.

Key words: Air chamber model, Centrifugal compressor, Rotating stall