Influence of the upstream slot geometry on the endwall cooling and phantom cooling of vane suction side surface

Modern gas turbines always operate at a high level of inlet temperature. The current inlet temperature in the aircraft and heavy duty gas turbines is higher than the melting point of the guide vane material. Consequently, advanced cooling schemes must be developed to ensure the safe operation of gas turbines. In the current study, numerical simulations were conducted to investigate the influence of the upstream slot geometry on the endwall cooling and phantom cooling of the vane suction side surface. Three-dimensional (3D) Reynolds-averaged Navier-Stokes (RANS) equations combined with the shear stress transport (SST) k - omega turbulence model were solved to conduct the simulations based on the validated turbulence model. The results indicate that the adiabatic cooling effectiveness in the upstream region of the stagnation is significantly increased by introducing the contoured upstream slot. However, the normal upstream slot obtains a relatively high adiabatic cooling effectiveness level in the downstream region of the stagnation. In the present research, the case with normalized amplitude (A) over bar = 0.75, initial phase angle phi = 45 degrees achieves the largest overall adiabatic cooling effectiveness near the vane leading edge. In contrast, the case with (A) over bar = 0.75, omega = 30 degrees attains the smallest overall adiabatic cooling effectiveness on the endwall surface. Moreover, the phantom cooling effectiveness on the vane suction side surface is relatively small relative to the adiabatic cooling effectiveness on the endwall. The case with the normal upstream slot achieves the largest phantom cooling effectiveness on the vane suction side surface compared with the contoured upstream slot. Overall, the contoured upstream slot significantly enhances the endwall cooling effectiveness by rearranging the distribution of the coolant mass flowrate at the slot outlet. (C) 2017 Elsevier Ltd. All rights reserved.