突肩叶尖开槽对叶尖间隙流动和冷却特性的影响

Effects of Squealer Tip Cutbacks on Tip Leakage Flow and Film-Cooling Characteristics

关键词:  突肩开槽  机匣相对运动  吹风比  间隙泄漏损失  气膜冷却效率

Key words:  Squealer cutback  Casing relative motion  Blowing ratio  Tip leakage loss  Film-cooling effectiveness

摘要:

为了分析不同叶尖形式下的间隙泄漏流动，采用标准[k-ε]两方程模型求解雷诺平均N-S方程组的数值方法，研究了突肩叶尖开槽对叶尖流动和冷却特性的影响，气膜孔位置、机匣相对运动和吹风比也在考虑范围之内，详细分析了间隙泄漏流场、泄漏流量、泄漏损失以及叶尖气膜冷却效率。研究结果表明:突肩叶尖前缘和尾缘开槽均会使间隙泄漏流量增大，且随着开槽长度的增加而增大。压力侧尾缘开槽会使间隙泄漏损失增大，叶尖气膜冷却效率略微降低；吸力侧尾缘开槽会使得部分泄漏流从开槽处流出间隙，抑制泄漏流与主流之间的掺混，从而减小泄漏损失，并且会使叶尖气膜冷却效率增大；吸力侧前缘开槽对间隙泄漏损失和叶尖气膜冷却效率没有明显影响，但是从前缘进入凹槽内的泄漏流会改变叶尖表面气膜冷却效率的分布。吹风比增大时叶尖结构对叶尖气膜冷却效率的影响减小。机匣相对运动会减小叶尖间隙泄漏流量、泄漏损失和叶尖气膜冷却效率，但是突肩开槽的影响规律不变。

Abstract:

In order to analyze the leakage flow of different tip configurations， standard two-equation [k-ε] model was adopted to study the effect of squealer tip cutbacks on tip leakage flow and film cooling characteristics by solving the Reynolds-averaged N-S equations. The film hole location， casing relative motion and blowing ratio were also taken into account. The tip leakage flow field， leakage flow rate， leakage loss and tip film-cooling effectiveness were analyzed in detail. The results show that squealer tip leading and trailing edge cutbacks can increase the tip leakage flow rate， which increases with the increase of the cutback length. The pressure side trailing edge cutback will increase the tip leakage loss， but decrease the tip film-cooling effectiveness. The suction side trailing edge cutback will make part of the leakage flow slip out at the cutback location and suppress the mixing between the tip leakage flow and mainstream， then decrease the tip leakage loss. In addition， the tip film-cooling effectiveness at the trailing edge will increase. The addition of the suction side leading edge cutback has tiny influence on the tip leakage loss and tip film-cooling effectiveness， but the leakage flow enter the cavity from the leading edge will change the tip film-cooling effectiveness distribution. The effects of tip geometries on the tip film-cooling effectiveness decrease when the blowing radio increases. The casing relative motion reduces the tip leakage mass flow rate， leakage loss and the tip film-cooling effectiveness， but the effect of the squealer cutbacks is the same.