旋转对涡轮叶片异型孔气膜冷却的影响

Effects of Rotation on Shaped-Hole Film

关键词:  涡轮叶片  异型孔  气膜冷却  旋转雷诺数  数值模拟

Key words:  Turbine blade  Shaped-hole  Film cooling  Rotational Reynolds number  Numerical simulation

摘要:

为了揭示异型气膜孔在旋转状态下的冷却特性，采用数值模拟的方法分析了吹风比为0.6时旋转对涡轮叶片异型气膜孔流动及冷却的影响，包括三种气膜孔:圆孔、扇形孔及收敛缝型孔。结果表明:旋转时气膜射流受离心力和哥氏力作用朝叶尖方向偏转，射流涡结构被弱化而变得不明显，气膜射流向主流的穿透得到一定程度的削弱；圆孔和扇形孔冷却效率随旋转雷诺数增大而升高，局部最多可分别提高100%和50%左右，收敛缝型孔冷却效率受旋转雷诺数的影响较小；旋转状态下扇形孔冷却效果与收敛缝型孔相当，仍然优于圆孔。

Abstract:

The effects of rotation on shaped-hole film flow and cooling on a turbine blade with a blowing ratio of 0.6 were investigated through numerical methods to figure out the cooling characteristics of shaped-holes with rotation，including the cylindrical hole，the fan-shaped hole and the converging slot-hole. The results show that the film jet deflects towards the blade tip due to the combined effects of centrifugal and Coriolis force derived from rotation. As a consequence，the integrated film vortex is weakened and becomes unconspicuous. Simultaneously，the penetration of the film jet to the mainstream is diminished to some extent. The cooling effectiveness improves with the increase of rotational Reynolds number with approximate regional 100% and 50% increment，respectively，with regard to the cylindrical hole and the fan-shaped hole whereas the converging slot-hole indicates a slight effect of the rotational Reynolds number on its cooling effectiveness. The fan-shaped hole is comparable to the converging slot-hole under rotational conditions where both outperform the cylindrical hole in terms of film cooling performance.