Redesign of a turbocharger compressor based on multi-component full-passage optimization

Abstract

Self-recirculation casing treatment (SRCT) is often used to improve the flow stability of turbocharger compressors. However, it usually introduces penalties of the peak efficiency or the choke margin of compressors though assisted by auto-optimizations. For this, a multi-component optimization of SRCT and diffuser for a turbocharger compressor is implemented based on the full-passage computational model with a volute. As a result, the aerodynamic performances of the compressor are improved over the whole speed line. Specifically, the efficiency and pressure ratio at the design condition are increased by 1.23% and 1.31% respectively, those at the near-stall condition are improved by 1.84% and 3.13% respectively. The choke flow rate is improved by 1.44%, and the stable flow range is expanded by 2.7 percentage points. The flow mechanisms are as follows. Firstly, the bleed slot width is increased, then the recirculation flow rates in different impeller passages are improved and the low-energy fluids in corresponding passages are removed. The blockages and the circumferential asymmetry in impeller passages are reduced, hence, the flow stability is improved. Secondly, the flow area of diffuser passages is enlarged due to the reduced solidity of vaned diffuser, and then the swallowing capacity of the compressor is improved. Also, the mismatching effect introduced by the SRCT is compensated by the reduced solidity of vaned diffuser. Finally, the injection slot angle and height are decreased, then the distortions and mixing losses in impeller inlet are reduced. Also, the aerodynamic losses in impeller inducer are reduced by removing more stagnation fluids near inducer shroud due to the increased bleed slot width.