离心叶轮叶顶间隙泄漏流影响因素的量化分析研究

Quantitative Analysis of Influence Factors on Leakage Flow of Tip Clearance in Centrifugal Impellers

关键词:  离心叶轮  叶顶间隙  泄漏流  量化分析

Key words:  Centrifugal impeller  Tip clearance  Leakage flow  Quantitative analysis

摘要:

为了定量研究离心叶轮叶顶泄漏流的影响因素，在经典闭式Eckardt叶轮基础上等值切削得到了11个相对间隙值在0～10%区间的半开式叶轮。采用数值计算分析和量化分析相结合的方法研究了叶轮设计工况下的顶隙流场，量化得到与间隙泄漏有关的叶顶载荷、刮削压头和泄漏强度沿流向的分布值。在完成“刮削率”R的计算讨论后，对量化的结果进行了偏最小二乘法(PLS)分析，建立了泄漏强度与泄漏流主要影响因素的定量关系式。研究结果表明，R值沿叶片流向从2.3下降到0.25左右，说明轮盖刮削对间隙泄漏流的作用沿流向增强；叶顶载荷的变量投影重要性值(［1，2］)略大于刮削压头的变量投影重要性值(［0.7，1］)，且叶顶载荷的回归系数值(［0.6，0.8］)略大于刮削压头的回归系数值(［0.4，0.6］)，说明叶顶载荷对间隙泄漏流的促进作用大于刮削压头，但刮削压头对间隙泄漏流的影响不可忽略。

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.