Large eddy simulation of surge inception and active surge control in a high speed centrifugal compressor with a vaned diffuser

In this study, we present a numerical investigation of active surge control and performance improvement for an aero engine centrifugal compressor (NASA CC3) using self-recirculating bleed slots with different bleeding positions. This investigation considers an unsteady three-dimensional numerical simulation based on large eddy simulation. Three bleeding slots positions are studied and compared with a compressor without surge control. The aim of the recirculating bleed slots is to remove some of the reversed flow during surge inception from the impeller inducer, which influences the stable operating range and compressor pressure ratio. The effects of the three bleeding slot positions on the internal flow and performance of the compressor are highlighted by a detailed analysis of the impeller flow field. The surge event stages are detected well inside the impeller and diffuser. The results show that an effective flow bleeding system can increase the surge limit compared with a classical compressor without a bleeding system. A comparison of the cases investigated in this study indicates that the surge limit increases by 8% for the bleeding slots located closer to the main blade leading edge, with lower increase in the surge limit for slots near the split blade's leading edge.