上游引导式槽缝射流的涡轮端壁气膜冷却效率实验研究

The upstream slot combined with downstream discrete holes is commonly used to cool the endwall of turbine vanes positioned just after the combustion chamber exit. This endwall surface is exposed to extreme heat loads and complex cascade vortices. However，the coolant distribution from the slot and discrete holes impacts both the cooling effectiveness and coverage of the film on the endwall surface. To explore this effect，this study investigates the film cooling characteristics of discrete holes and a slot/discrete hole combination at varying mass flow ratios（MFR）using pressure-sensitive paint（PSP）technique. Additionally，the study examines how coolant distribution and slot height influence the cumulative film cooling effectiveness for downstream discrete holes. Results reveal that a low-cooling region forms on the pressure side at low MFR. As MFR increases，the cooling effectiveness in this area improves significantly. At low MFR，discrete holes alone outperform the combined structure in cooling effect. However，as MFR rises，the benefits of the combined structure become more evident，markedly enhancing cooling effectiveness on the pressure side. At an MFR of 1.5%，the combined structure achieves film cooling effectiveness 1.33 times greater than that of discrete holes，with a 32.1% improvement in area-averaged film cooling effectiveness. Lowering the slot height enhances coolant attachment，resulting in better cooling performance. Reducing slot height and increasing MFR can significantly boost peak film cooling effectiveness and axial coverage on the endwall.