气膜孔形状对涡轮叶片气膜冷却效果的影响

基于控制容积法对三维定常不可压缩N-S方程进行离散,采用非结构化网格及两层k-ε湍流模型,在吹风比M为0.6和1.2的情况下,数值模拟了气膜孔几何形状对涡轮叶片气膜冷却效果的影响,得到了气膜孔附近的流场分布.所选孔形为圆柱孔、前向扩张孔、开槽前向扩张孔及新型缩放槽缝孔.结果表明:圆柱孔的冷却效率随着吹风比的增加而显著地降低;开槽前向扩张孔的冷却效率优于圆柱孔和前向扩张孔;缩放槽缝孔在不同吹风比下的冷却效率均高于其它3种孔形,缩放槽缝孔和开槽前向扩张孔不同程度地抑制了反向涡旋对的产生,提高了射流对壁面的贴附性,增强了壁面的冷却效果.

Influence of Air-film Hole Shapes on Turbine Blade Air-film Cooling Effectiveness

On the basis of a bulk flow control method,discretized was a three-dimensional steady incompressible N-S equation.By using a non-structured grid and two-layer k-ε turbulent flow model and under the condition of the air blowing ratio M being 0.6 and 1.2,numerically simulated was the influence of air-film hole shapes on turbine blade air-film cooling effectiveness,and obtained was the flow field distribution around the air-film holes.The hole shapes chosen were cylindrical,forward flared,slot-shaped forward flared and new type converging-diverging slotted holes.It has been found that the cooling efficiency of cylindrical holes is reduced significantly with an increase of the air blowing ratio,the cooling efficiency of slot-shaped forward flared holes is superior to that of cylindrical and forward flared holes and the cooling efficiency of converging-diverging slotted holes at different air blowing ratios is invariably higher than that of the other three kinds of hole shapes.The converging-diverging slotted holes and slot-shaped forward flared holes can restrain the production of reverse vortex pairs to a certain extent and strengthen the wall-adhesion property of jet flows,thus enhancing the cooling effectiveness to wall surfaces.