Turbine vane endwall film cooling with barchan-dune shaped ramp in a single-passage transonic wind tunnel

In this study, the film cooling effectiveness of a turbine vane endwall was quantified using the pressure-sensitive paint (PSP) technique. With circular holes serving as the baseline, a barchan-dune shaped ramp (BDSR) was compared side by side to examine its endwall cooling performance in a single-passage wind tunnel at Ma = 0.84. Carbon dioxide was used as coolant, which was discharged into the endwall model. The slot was fed by a constant blowing ratio of M = 0.3, while the coolant holes were set to be M = 0.5, 1.0, 1.5, and 2.0. The results showed an asymmetrical coolant distribution for both circular holes and BDSR, with the highest cooling effectiveness near the suction side (SS) and the lowest near the pressure side (PS). This behavior was caused by the passage flow structures, where the coolant aligned with the vortex lines and flowed toward the SS. Compared with the baseline, the BDSR demonstrated significantly increased cooling performance in the near-SS regions. The presence of a dune ramp is particularly beneficial for endwall cooling at high blowing ratios. As revealed by numerical simulations, the induced anticounter-rotating vortex pair (CRVP) in the BDSR countervails the detrimental effect of CRVP and greatly improves the endwall cooling performance. (C) 2020 Elsevier Ltd. All rights reserved.