减少透平叶栅中二次流损失方法的试验研究

RESEARCH ON METHODS FOR REDUCING THE SECONDARY FLOW LOSSES IN TURBINE CASCADES

在大容量汽轮机的高、中压级中,一般相对叶高比较小,尤其是调节级的相对叶高更小,通常都小于0.5(如国产125MW汽轮机的调节级相对叶高为0.22)。根据文献[1、2],在这类叶栅中,二次流损失占的比例相当高,达50％以上。因此,减少汽轮机调节级以及高、中压级的二次流损失,对提高级效率,将有很重要的经济意义。

This article deals with two methods of reducing secondary flow losses. One is meridional profiling, and another is protracting blade entering edge with simultaneous meridional profiling. Test results show that at lower aspect ratios (l = 0.22-0.35) the effects are substantial in case of simultaneous end wall profiling at both tip and hub. Tests with same blade heights also show that by reducing blade cord length to enlarge aspect ratio with simultaneous protraction of blade entering edge for strength's sake, the secondary flow losses are reduced as compared to the original large profile blades.