SAE International Research on Transonic Centrifugal Compressor Blades Tip Clearance Distribution of Vehicle Turbocharger 2008-01-1701

Flow induced by blades tip clearance is important for centrifugal compressor, especially for the high charging ratio transonic centrifugal compressor of vehicle. Based on three-dimensional CFD method, the flow fields of two opposite impeller blades tip clearance distribution compressor stages with vaneless diffuser are analyzed. The law and action mechanism of tip clearance distribution effect on the high charging ratio transonic centrifugal compressor impeller and vaneless diffuser performance are researched. It is verified that the pressure ratio and efficiency of compressor stage whose aft axial clearance height is smaller than fore radial clearance height is higher than that of compressor stage whose aft axial clearance height is larger than fore radial clearance height. The smaller aft axial clearance height weakens the flow in aft half of impeller passage, improves impeller aft passage power input and obtains higher impeller pressure ratio and compressor stage pressure ratio. The smaller aft axial clearance height gets higher efficiency because it reduces impeller aft blades tip clearance leakage vortices intensity and imposes the vortices breakdown and dissipation loss less in impeller passage exit and vaneless diffuser passage. The research of the impeller blades tip clearance distribution effect on vehicle transonic centrifugal compressor performance and flow structure lays a foundation for transonic centrifugal compressor flow control.