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 commerce computational fluid dynamjcs(CFD) software CFX adopting RNG k-ε turbulence model are presented in this paper.Firstly

the steady performance curve is obtained using steady calculations and compared with experimental results. Secondly

a plenum chamber model is added at the vaneless diffuser outlet to simulate the rotating stall flow phenomenon inside the centrifugal compressor.The paper gives the centrifugal compressor internal flow fields at different times during the stall cycle at the least mass flow rate and observes the stall flow phenomenon.The plenum chamber influence on the rotating stall is also investigated.The simulation indicates the more the plenum chamber volume

the lower the stall frequency.