涡轮叶栅端壁气膜冷却数值模拟

Numerical simulation of endwall film-cooling in a turbine cascade

对前缘上游有双排气膜孔的涡轮叶栅端壁气膜冷却进行了气动和传热数值模拟。计算模拟了两排26个气膜孔,每个孔截面的网格数达到近200个,计算域包括了供气腔。计算得到了端壁气膜冷却的冷却效率分布并进行了冷气射流粒子示踪。计算揭示了端壁气膜冷却的流动与传热传质机理,并据此提出了端壁抛射气膜冷却的概念。结果表明数值计算可模拟气膜冷却的主要流动与传热特征,但在数值的准确性上还需要进一步的完善。

Detailed numerical simulations on the three-dimensional turbulent flow and heat transfer were carried out in a turbine cascade with double row injection on the end-wall upstream of leading edge. The computational domain were extended to the coolant supply plenum, and two rows of 26 film cooling holes were simulated, with about 200 cells across each orifice cross-section. RNG k-Ε turbulence model was used. The three-dimensional coolant flow path lines in the cascade and the film cooling effectiveness on the end-wall were obtained. The results show that the basic flow and heat transfer patterns of end-wall film cooling are well simulated, but further improvement on the accuracy of numerical simulation is needed. A new cooling concept named trajectory film cooling is presented based on the uncovered flow and heat and mass transfer mechanism of upstream leading edge end-wall injection.