关键词: 离心叶轮；叶顶间隙；泄漏流；量化分析

Abstract: In order to quantitatively investigate the main influence factors on the tip leakage flow of centrifugal impellers，11 unshroud impellers whose relative values of the tip clearance range from 0 to 10 percent are generated from the typical shrouded Eckardt impeller by equivalent cutting. Numerical simulation and quantitative analysis method are used to investigate the flow field around different tip clearances in the design condition，and then the factors related to the leakage flow，namely，the leakage intensity，scrapping pressure and tip load are quantified along the spanwise direction. After the calculation and discussion of "Scrapping Ratio" R，the quantified results are analyzed by the Partial least square (PLS) method. Finally，the quantitative formulas describing the relationship between the leakage flow and its main influence factors are established. The study shows that: (1)The value of R falls from 2.3 to about 0.25，which indicates that the effects of shroud scrapping on leakage flow increase along the spanwise direction. (2)The variable importance projection value of tip load (interval ［1，2］)is a little bigger than the variable importance projection value of scrapping pressure (interval ［0.7，1］)，and the regression coefficient value of tip load (interval ［0.7，1］) is a little bigger than the regression coefficient value of scrapping pressure (interval ［0.6，0.8］)，which indicates that tip load plays a much more important role in promoting the leakage flow than scrapping pressure，but the influence of scrapping pressure on leakage flow can not be ignored.

Key words: Centrifugal impeller；Tip clearance；Leakage flow；Quantitative analysis