Experimental investigation on the effect of internal rib turbulators on film cooling effectiveness with coolant cross-flow

This study primarily investigates the effects of rib turbulators with and without coolant cross-flow on the air-cooled turbine vane film cooling effectiveness (η), using PSP (pressure-sensitive paint) technology. In the experiments, film cooling effectiveness contours of three different test vanes were measured: a smooth vane without rib, a vane with 30° angled ribs, and a vane with 90° angled ribs. The effects of coolant cross-flow SR (suction ratio), BR (blowing ratio), and rib orientation angle were investigated. The experimental results show that the vane surface film cooling effectiveness is affected by cooling passage geometric parameters and mainstream/secondary-flow flow characteristics. Both cross-flow and rib turbulators can improve the film cooling effectiveness. As the cross-flow destroyed the counter-rotating vortex pairs in the film hole and at the film hole outlet, the overall-averaged film cooling effectiveness of the 90° angled ribs vane with cross-flow was increased by 6.39% than that without cross-flow. As BR increased from 0.3 to 1.0, the overall-averaged film cooling effectiveness of 30° angled ribs vane decreased by 80.9% without cross-flow and 56.4% with cross-flow. The internal ribs produced the secondary swirl in the cooling passage. As the swirl direction was close to the film hole inclined direction, the coolant was easier to flow into the film hole. Based on film cooling effectiveness of smooth vane without cross-flow, the overall-averaged film cooling effectiveness of vanes with different rib angles was increased by 24.56–45.69% and the overall-averaged film cooling effectiveness of 30° angled ribs vane was slightly higher than that of 90° angled ribs vane.