出流结构对涡轮叶栅端壁气膜冷却效率数值研究

通过对涡轮叶栅端壁上游不同气膜冷却结构模型进行数值模拟,得到了不同吹风比情况下,涡轮叶栅端壁的流动与换热特性.结果表明:圆柱形孔冷气射流在孔下游与主流相互作用形成一对转动方向相反的耦合涡,对涡轮叶栅端壁的气膜冷却效果不利.前向扩张孔降低了孔下游耦合涡的强度,对涡轮叶栅端壁总体气膜冷却效率要优于圆柱形孔.前向扩张缝结构增大了射流宽度,冷却了孔间端壁,对涡轮叶栅端壁总体气膜冷却效率要优于圆柱形孔和前向扩张孔.

Numerical study on film-cooling effectiveness on endwall of a turbine cascade by different film-cooling jet structures

Numerical simulation was carried out to investigate the influence on film-cooling effectiveness by different structures,and the flow and heat transfer characteristics on endwall of a turbine cascade at different blowing ratios were obtained. The result shows that the jet of column holes produces a pair of coupling counter-rotating vortices at the downstream of cooling holes by the influence of mainstream and cooling jet. The vortices are disadvantageous to the endwall film-cooling. The forward expansion hole reduces the intensity of coupling vortices. The cooling jet is pushed to the wall. These factors make the cooling effectiveness better than the column cooling holes. The forward expansion leakage increases the width of jet,and cools down the endwall between the film-cooling holes. These factors make the forward expansion leakage better than the column holes and forward expansion holes.