气动参数对后台阶三维缝隙气膜冷却效率的影响

Effect of Aerodynamic Parameters of Backward-Step Three Dimensional Slots on Film Cooling Effectiveness

针对涡轮叶片尾缘冷却结构特点,建立了后台阶三维缝隙结构气膜冷却特性试验台,测量了缝隙中心和肋中心下游气膜冷却效率的局部分布,研究了气动参数变化对冷却效率的影响,其中基于缝高的二次流雷诺数变化范围是5 000~15 000,吹风比变化范围是0.5~2.0。试验结果表明:(1)二次流雷诺数对下游冷却效率的影响较小,对三维掺混区域的范围影响也不大;(2)吹风比对冷却效率有较大影响,总体上冷却效率随吹风比增大而降低;(3)吹风比对三维掺混区的范围及三维掺混的特征均有较大影响,吹风比较低时,二次流向两侧肋后区域的流动扩散性较好,有利于提高整个被保护面的冷却效率,吹风比较高时,二次流向两侧肋后区域的流动扩散性较差,造成肋后区域冷却效率较低。

According to the feature of the turbine blade trailing edge cooling ,film cooling effectiveness of backward-step three dimensional slots injection was measured at the slot center line and rib center line. The effects of aerodynamic parameters on the film cooling effectiveness have been studied. The secondary flow Reynolds number based on slot height varied from 5 000 to 15 000 and blowing ratio changed from 0.5 to 2.0. The experimental results show that the influence of secondary flow Reynolds Number on film cooling effectiveness and three dimensional flow mixing region is unremarkable;the influence of blowing ratio on film cooling effectiveness,and the size and performance of the three dimensional mixing flow region is very significant. For lower blowing ratio ,secondary flow will flow into mainstream region and the region behind the rib, this will benefit the protected wall^for high blowing ratio,the situation is the contrary.