Analysis of the tip clearance flow structure in a centrifugal compressor

In this paper, the krain impeller with a pressure ration of 4.7 is choose as the study object. The blade tip clearance flow structures at different operating conditions and the effects of the radial distortion at impeller inlet on the tip clearance flow are investigated by CFD. The results show that, the losses induced by tip clearance flow enhance and the interface between tip clearance vortex trajectory and main flow moves forward as the mass flow rate decrease, and the interface spills out the leading edge of adjacent blade at stall condition. The losses induced by tip clearance flow enhance and the angle between tip clearance vortex trajectory and main flow decreases as the tip clearance increases. Increasing the fluid momentum in the blade tip region is an effective method to delay the spilling out the blade leading edge of tip clearance flow, and conversely, it will promote the spilling out.