Transonic vane film cooling with crescent-shaped craters using an endoscopic pressure-sensitive paint technique

This study examined the cooling performance of a crescent-shaped crater (CSC) hole design along the pressure side of a transonic vane. The adiabatic effectiveness of the CSC holes and circular holes was measured via an endoscopic pressure-sensitive paint (PSP) technique in a transonic wind tunnel at Ma = 0.84. Coolant flow (CO2) was discharged into the mainstream flow through two rows of holes, with the blowing ratio (M) varying from 0.6 to 1.2. The measured cooling effectiveness of the CSC hole was significantly higher than that of the circular design, demonstrating similar to 57% and similar to 38% enhancements in area-averaged effectiveness at M = 0.8 and 1.0, respectively. The physics of the CSC hole design was further explored by numerical simulations, which reveal the generated vortex structures and aerodynamic losses under various conditions. Specifically, the simulations demonstrated the features of anti-counter-rotating vortex pairs for CSC holes, which partially counteracted the detrimental effect of counter-rotating vortex pairs, thereby greatly improving the cooling effectiveness along the vane's pressure side.