Study on Tip Clearance Flow of Turbine
Blade-Endwall Secondary Flow Structure
Qi Mingxu,Feng Zhenping
(Institute of Turbomachinery, Xi'an Jiaotong University, Xi'an 710049, China)
Abstract: Numerical simulations on Aachen 1-1£¯2 axial-flow turbine stages with
different tip clearances were performed. Based on the distributions of secondary velocity
and averaged azimuthal flow angle, the form of mixing process of tip clearance vortex with
passage vortex and its influences on secondary flow structure were studied. The results
show that tip clearance vortex forms earlier under larger tip clearance, accompanied with
decreased intension and increased size during its development downstream-wise.
Moreover,under small tip clearance or in the location nearby leading edge, the passage
vortex is only shifted by tip clearance flow while integrity being preserved. However,
under larger tip clearance or in the high-loaded area, passage vortex is divided into two
independent vortices which are shifted towards pressure side and mid-span, while tip
vortex occupies a large tip area near endwall. In addition,two different endwall secondary
flow structures were presented.
Keywords: tip clearance flow; tip clearance vortex; passage vortex; secondary flow