Effects of Tip Injection on Tip Clearance Flow in a Low-Pressure Turbine Stator Cascade

Abstract

Taking into account the tip leakage flow will cause the loss of a substantial increase, how to effectively control the tip clearance flow has become a current research focus. In this paper, the effects of tip injection in a low pressure turbine cascade with different injection locations, number of injection holes and mass flow rate are investigated in detail. The SST k-ω turbulence model on the basis of the Gamma-Re transition model is adopted to compute the three-dimensional flow in the cascade of a turbine cascade with tip clearance. The feasibility of a commercial computational fluid dynamic code was validated and the computed data showed a good agreement with experimental data. The effect of the tip injection locations at camber line is better than that of close to the suction side or the pressure side. The total pressure loss decreased significantly by about 22% by increasing the injection flow rate to 6g/s. The main purpose of tip injection for the control of tip clearance flow is not simple to decrease the mass flow rate of leakage flow. There needs to be a more reasonable tip injection scheme which must consider the unfavorable effects of flow blockage in the clearance, and the losses due to the mixing of injection flow with tip clearance flow and leakage flow with main flow are reduced in order to achieve the optimal effect of clearance flow control.