具有相反横向射流角的全覆盖气膜孔冷却特性

通过数值计算的方法对全覆盖气膜冷却结构的流场特性、壁面表面传热系数、绝热壁面气膜冷却效率以及考虑固体导热影响下的综合冷却效率进行了对比研究.结果显示:相反横向射流角产生的反肾形涡对使冷气侧向扩散能力更强;虽然表面传热系数升高,但是由于较高的绝热壁面气膜冷却效率降低了传入固体壁面的热量,提升综合冷却效率.吹风比为1.0时,45°相反横向射流角斜孔有最高的综合冷却效率.当吹风比为1.5和2.0时,30°相反横向射流角斜孔有最高综合冷却效率.与相同横向射流角斜孔作对比,15°相反横向射流角斜孔综合冷却效率不及15°相同横向射流角斜孔,45°,60°相反横向射流角斜孔综合冷却效率在不同流向长度上与相同横向射流角斜孔综合冷却效率相差不大,30°相反横向射流角斜孔综合冷却效率高于相同横向射流角斜孔.

Cooling characteristics of full coverage film holes with opposite lateral ejection angles

Numerical investigations were performed to study the full coverage film cooling structure on the flow field characteristics, wall surface heat transfer coefficient, adiabatic wall film cooling effectiveness and integrated cooling effectiveness under consideration of heat conduction. Results indicates that kidney vortex pair generated in the flow field of film cooling with opposite lateral ejection angles makes the film spread wider laterally. Despite of raised heat transfer in this condition, the integrated cooling effectiveness increases as high adiabatic wall cooling effectiveness reduces the heat conduction. Under blowing ratio of 1.0, the slant hole with opposite lateral ejection angle of 45° has the highest integrated cooling effectiveness. The integrated cooling effectiveness of slant hole with opposite lateral ejection angle of 30° is the highest when blowing ratio of 1.5 and 2.0. Compared with corresponding slant hole with single lateral ejection angle, the film cooling with opposite lateral ejection angle of 15° has lower integrated cooling effectiveness. The cooling effectiveness of slant hole with opposite lateral ejection angles of 45° and 60° respectively are both comparable to the integrated cooling effectiveness of the corresponding structures with single lateral ejection angle. When compared with slant hole with single lateral ejection angle of 30°, the film cooling with opposite lateral ejection angle of 30° has higher integrated cooling effectiveness.