Impact of Cooling Injection on the Transonic Over-Tip Leakage Flow and Squealer Aerothermal Design Optimization

In the present work, the effect of coolant injection on the over-tip-leakage (OTL) flow and squealer designs has been investigated in a transonic flow regime. After an experimental verification of the computational tool adopted for capturing transonic flow characteristics, a series of quasi-three-dimensional (3D) computational analyses were carried out to reveal and understand the cooling jet - OTL flow interaction at various hole locations and inclination angles. The results indicate that the performance rankings between flat tip and squealer tip designs might be altered by the addition of cooling injection. Full 3D conjugate heat transfer analyses demonstrate that partially replacing the squealer cavity with a simple flat shaped configuration in the rear transonic flow portion would offer a much improved coolability without paying extra aerodynamic penalty.