The Aerothermal Performance of Tip Leakage Flow in High Pressure Turbines

Future aero engines are expected to achieve higher efficiencies and lower emissions, which brings new challenges for turbine designers. In a high-pressure turbine, tip clearances exist between the turbine rotor blade tip and the casing to prevent rubbing. The pressure difference between the blade pressure side and the suction side drives the gas across this tip clearance gap. The high-temperature gas results in excessively high metal temperatures on the blade tip, which lead to thermal erosion and oxidation. Obtaining good aerothermal performance is the key to maintain the performance of the high pressure turbines. The current talk will present a combined experimental and numerical study, which aims to understand the performance of the tip leakage flow and to develop new tip configurations for higher engine efficiency. First, the aerodynamic and heat transfer performance of squealer tips will be discussed. The effects of the squealer height and thickness will be investigated. Then, the tips with coolant injection are investigated to understand the effects of the cooling air on the loss mechanism and tip heat transfer. Finally, winglet configurations are used on blade tips to reduce the tip leakage loss. The results showed that by using the winglet tip developed in the current study, the turbine stage efficiency increases.