非定常尾迹对叶栅气膜冷却效率的影响

Effect of unsteady wake on linear cascade film cooling efficiency

关键词:  非定常流  叶栅尾流  薄膜冷却  效率  局部吹风比+

Key words:  Unsteady flow  Cascade wake  Film cooling  Effeciency  Local blowing ratio~+

摘要:

通过实验的方法研究了非定常尾迹对气膜冷却效率的影响,在平面叶栅实验台上安装了尾迹发生器,用来产生非定常尾迹。用热电偶测量了雷诺数5 04×104,1 08×105,斯托劳哈儿数0 04～0 18时气膜的绝热冷却效率,通过实验数据分析了非定常尾迹的宽度和扫过频率对气膜绝热冷却效率的影响。发现非定常尾迹通过两方面来影响气膜冷却效率,一方面是通过对气膜层的扰动来降低气膜冷却效率,另一方面是通过改变局部吹风比来影响气膜冷却效率。

Abstract:

The effect of unsteady wake on film cooling effectiveness was experimentally determined. A squirrel cage type wake generator produced the unsteady wake. Experiments were performed in a low-speed wind tunnel at the Reynolds number of 5.04×10~4,1.08×10~4,and at the wake Strouhal number of 0.04～0.18. Results show that an increase in the wake Strouhal number causes a decrease in film effectiveness at the Reynolds number of 5.04×10~4, but at the Reynolds number of 1.08×10~5, the wake of wake generator with 6mm rod causes an increase in film effectiveness. Unsteady wake affects film cooling effectiveness by two ways.One is to disturb the film cooling layer, the other is to change the local blowing ratio.