Influence of the pressure side injection slot on the cooling performance of endwall surface

ABSTRACT

In modern gas turbine engines, the first stage vane endwall endures high thermal load with the increase of the turbine inlet temperature and the uniformity of the temperature distribution at combustor outlet. Moreover, the endwall secondary flow forces the coolant flow toward the suction side, resulting in hot regions along the pressure side endwall. In the worst case, hot regions lead to thermal failure. In order to ensure that the gas turbine operates safely, advanced cooling techniques are urgently needed to be implemented to reduce the hot regions along the pressure side endwall. In the current research, the influences of the pressure side injection slot on the film cooling performance of the endwall surface were numerically investigated. The three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations combined with the shear stress transport (SST) turbulence model were solved to conduct the simulations. Cases with different injection slot configurations have been simulated. The results indicate that the hot region along the pressure side endwall is significantly reduced by introducing the pressure side injection slot. The coolant from the pressure side injection slot is assisted by the pressure side vertical flow toward the adjacent vane suction side. Therefore, the coolant coverage and the cooling effectiveness are increased. In this study, the expanded slot (ES) achieves a larger cooling effectiveness than the normal slot (NS) and convergent slot (CS) at a small blowing ratio M = 0.5. In contrast, the CS obtains a larger cooling effectiveness than the NS and ES at M = 1.0 and M = 1.5. In addition, the introduction of the pressure side injection slot has a small influence on the aerodynamic performance of the vane cascade.

Acknowledgments

The authors gratefully acknowledge the support of China Scholarship Council (CSC), the National Natural Science Foundation of China [No. 51776151], the Swedish Research Council (VR) and the Swedish National Energy Agency (EM).