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    燃气轮机涡轮叶片气膜孔出口扇形化的影响

    Influence of Fan-shaped Outlet of Film Holes on Gas Turbine Blades

    • 摘要: 采用数值模拟方法将圆柱孔、双喷孔和姐妹孔的出口转化为扇形,并在不同吹风比M下将不同孔型与原始结构进行比较,冷却工质分别为空气和液滴/空气混合物。结果表明:将圆柱孔和姐妹孔的出口转变为扇形将导致气膜冷却效率(FCE)明显降低;当M为0.50和0.75时,将双喷孔的出口转变为扇形是有利的,但当M为1.25和1.50时,双喷扇形孔的FCE仍低于双喷孔;与原始结构相比,扇形出口产生的肾形涡对更强,冷却气膜更容易脱离被冷却表面,同时在低吹风比下扇形出口有利于冷却工质的展向扩展;将液滴注入冷却空气中可以明显改善FCE;在真实叶片上,姐妹孔在叶片上3个位置均实现最佳FCE。

       

      Abstract: Numerical simulation method was used to transform the outlet of cylindrical holes (CH), double-jet holes (DJH) and big-small holes (BSH) into fan-shaped holes, and different hole types were compared with the original structures under different blowing ratios (M) with the cooling fluid of air and droplet/air mixture, respectively. Results show that transforming the outlet of CH and BSH into fan shape causes an apparent decrease in the film cooling effectiveness (FCE). Transforming the outlet of DJH into fan shape is advantageous when M=0.50 and 0.75, but it reduces the FCE when M=1.25 and 1.50. Compared to the original structures, fan-shaped outlet produces a stronger rotating kidney vortex pair, making it easier for the cooling film to detach from the cooled surface. Meanwhile, fan-shaped outlet contributes to the spanwise expansion of cooling fluid under low blowing ratio condition. Injecting droplet into cooling air can evidently improve the FCE. On real blades, the BSH achieve the best FCE at all three positions.

       

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