Abstract: Influence of transverse slot configuration on film cooling effectiveness at the blade were investigated using a three-dimensional finite volume method and multi-block technique at the blowing ratio ranging from 0.6 to 1.8. Previous successful application of a two-layer turbulence model to cylindrical is extended to predict film cooling for the six kinds of trench hole. Also, flim cooling performance from transverse slot was compared with that of cylindrical hole. The results showed that effectiveness of all of trench hole was better than that of cylindrical hole at any blowing ratio. Film cooling effectiveness of several kinds of trench hole was almost consistent at low blowing ratio. Change trend of effectiveness of different trench hole was unlikeness along with increasing blowing ratio. Cooling effect of trench hole with moderate depth and maximal width was best among other cases and cooling effect of trench hole with maximal depth was reduced. It is also found that the momentum was depressed on account of area of jet flow abruptly increased when the jet was injected into the slot. The penetration of the film secondary flow into the mainstream flow was suppressed and the secondary flow was pushed downwards onto the surface, so the counter rotating vortex pairs have been weakened for the trench hole and results in a better coolant protection.

Key words: Film cooling; Transverse slot; Cooling effectiveness; Blowing ratio; Numerical simulation

摘要： 基于有限体积法对三维定常不可压缩N-S方程进行离散,采用两层k-ε湍流模型,在吹风比M为0.6,1.2和1.8的情况下,数值研究了6种不同横向槽结构对气膜冷却效果的影响,并与常规圆柱孔进行了比较。结果表明:在任何吹风比下,所有开槽孔的冷却效率均高于圆柱孔；在低吹风比时,6种开槽孔的冷却效率相差不大,随着吹风比的增大,不同开槽孔冷却效率的变化趋势不尽相同；具有中等开槽深度(0.75D)和最大开槽宽度(3D)的开槽孔,气膜冷却效果最佳,而具有最大开槽深度(1D)的开槽孔,气膜冷却效果较差；横向槽的存在使冷气射流在流出气膜后面积突扩,动量降低,气膜出流向主流的垂直穿透能力随之降低,射流本身流动的扩散以及射流在流入横向槽中受到主流对其向下的压制作用较大,反向涡旋对的强度不同程度地受到了抑制,增强了壁面的冷却效果。

关键词: 气膜冷却;横向槽;冷却效率;吹风比;数值仿真