Numerical simulation of active control on tip leakage flow in axial turbine

A 3-D Reynolds-averaged Navier-Stokes equations computational fluid dynamics(CFD) code,together with pressure-correction based Reynolds stress model and wall function was used to simulate the effects of tip clearance injection active control on the tip leakage flow in a turbine rotor.The results show that the injection can have a beneficial effect on turbine rotor efficiency by selecting properly the injection hole location.The efficiency can increase nearly by 0.35 percent with the jet of combined injection hole in loose tip clearance,so does the efficiency by 0.3 percent in tight tip clearance.The number of saddle is equal to that of node in the region of injection hole in tip platform,which satisfies the singularity point total number.