Abstract
The CFD analysis was conducted to investigate the effect of impeller tip clearance on internal flow in a centrifugal compressor with vaned diffuser. In previous studies, the leading-edge vortex (LEV) was produced near the diffuser leading-edge and the growth of the LEV deteriorated compressor performance. In addition, the LEV was enlarged by the tip-leakage vortex. In case of using impeller without clearance, corner vortex produced on pressure side of the impeller plays a similar role to tip-leakage vortex. Furthermore, the LEV develops and forms a huge flow blockage within diffuser passages at off-design operation, considering impeller tip clearance. However, the flow fields in diffuser passages were stable because the LEV was stationary on the suction side of the diffuser leading-edge in analysis of using impeller without tip clearance. Therefore, the tip-leakage vortex was considered to be the cause of diffuser stall at off-design operation.
