孔间距对缩放槽缝孔气膜冷却效率的影响

Influence of Hole Pitch on Film Cooling Effectiveness From Converging Slot-hole

基于有限体积法对三维定常不可压缩N-S方程进行离散,采用分区域非结构化网格及两层k-ε湍流模型,在吹风比M为0.4、0.8和1.6的情况下,数值研究了孔间距(P/D=3.0、3.5、4.0)对缩放槽缝孔气膜冷却效率的影响,对不同孔间距气膜冷却整体效果进行了对比分析。结果表明:孔间距较小时,在孔口附近及孔间区域发生强烈的气膜干扰,冷却气膜分布比较集中,在孔口下游近处冷却效率较高;随着孔间距的增大,气膜覆盖面积增加,孔口附近的冷却效率低于小孔距,各个孔沿展向的冷却效率也有所降低,在孔下游远处发生的气膜干涉较为明显;在低吹风比时,孔间距较小气膜孔的冷却效果最好,在高吹风比时,孔间距较大气膜孔对壁面的冷却效果与低吹风比相比有大幅度的改善。

Influence of hole pitch on film cooling effectiveness form converging slot-holes at the blade were investigated using a three-dimensional finite volume method and multi-block technique at the blowing ratio ranging from 0.4 to 1.6. Previous successful application of a two-layer turbulence model to cylindrical is extended to predict film cooling for the converging slot-hole geometry. Also, Flim cooling performances from different hole pitch were analyzed. The results showed that intensive disturbance was happened at nearby injection outlet and between two holes for short hole pitch. It caused film cooling distributed convergence, and the improvement for cooling effectiveness realized by downstream the holes, but film coverage was poor. The broad coverage realized by the increase hole pitch, and but cooling effectiveness was low by comparison with short pitch at injection outlet. In addition, intensive interference of film was very clear at a bit far downstream the holes. For short hole pitch, the film cooling effect had best at low blowing ratio, and the cooling effect of long hole pitch was remarkably improved at high blowing ratio compared with cooling effect at low blowing ratio.