Qi Mingxu,Feng Zhenping
(Institute of Turbomachinery,Xi'an Jiaotong University,Xi'an 710049,China)
Abstract:Numerical simulations on tip clearance flow in Aachen 1.1／2 axial-flow turbine stages are performed.The formation and development of tip clearance flow and tip vortex and the influences on turbine performances are investigated.With the aid of 3D streamline and limited streamline,the differences of formation and development of tip clearance flow and vortex as well as the difference of total pressure loss region in individual tip clearance sizes,are analyzed.It is found that with the increasing of tip clearance,the isentropic efficiency of turbine decreases linearly,the location of tip vortex moves up,the vortex intensity and the loss gradually increase,and the location and area of high losses are changed as the passage vortex is broken down and high loss region is transferred to pressure surface．
Keywords:axial-flow turbine;tip clearance flow;tip clearance vortex