冲击距与气膜孔方位角对旋流气膜冷却性能影响

Effects of Impingement Distance and Film Hole

关键词:  旋流气膜冷却  冲击距  气膜孔方位角  气膜冷却效率  肾形涡

Key words:  Film cooling with swirling coolant flow  Impingement distance  Film hole angle of orientation  Film cooling effectiveness  Kidney eddies

摘要:

为了获得冲击距[Hi]与气膜孔方位角α对旋流气膜冷却性能的影响规律，以六边形供气腔圆形气膜孔平板气膜冷却结构为研究对象，对五种冲击距参数(0.74D，1.14D，1.54D，1.94D，2.34D)(D为气膜孔直径)和五种气膜孔方位角参数(0°，10°，15°，20°，25°)进行了三维数值计算研究，得到了绝热壁面气膜冷却效率、展向平均气膜冷却效率、流场空间无量纲浓度分布等随冲击距与气膜孔方位角的变化规律，分析了肾形涡对旋流气膜冷却性能的影响机理。结果表明:冲击距对绝热壁面气膜冷却效率展向分布规律影响不大，而方位角增加能够明显提高绝热壁面气膜冷却效率及展向气膜覆盖面积，方位角0°模型展向气膜冷却效率最大值为0.42，方位角25°模型的最大值为0.48，相比前者增加14.3%；绝热壁面同一流向位置的展向平均气膜冷却效率随冲击距的增加而增大，随方位角的增加而增大，[Hi]=2.34D时的展向平均气膜冷却效率最佳，α=20°时的展向平均气膜冷却效率曲线最佳。方位角的增加能够明显破坏流场中存在的肾形涡结构。

Abstract:

In order to obtain the effects of impingement distance [Hi] and film hole angle of orientation α on performance of film cooling with swirling coolant flow，a series of 3D numerical simulation including five kinds of [Hi] parameter (0.74D，1.14D，1.54D，1.94D，2.34D)(D is the film hole diameter) and five kinds of α parameter (0°，10°，15°，20°，25°) were conducted and the flow field of flat plate film cooling using cylindrical hole with swirling coolant flow in a hexagonal cavity were studied. Rules of film cooling effectiveness of the adiabatic wall，spanwise-averaged film cooling effectiveness，spatial non-dimensional concentration changed with [Hi] and α have been obtained. The impact mechanism of kidney eddies structure on cooling performance of swirling coolant flow have been analyzed. Results show that the effects of [Hi] on the spanwise rules of film cooling effectiveness of the adiabatic wall are slight，but the increase of α does improve the film cooling effectiveness and the spanwise film coverage of the adiabatic wall. Compared with the maximum of the spanwise film cooling effectiveness 0.42 at α=0°，the maximum value 0.48 at α=25° increased by 14.3%. At the same streamwise location of the adiabatic wall，the spanwise-averaged film cooling effectiveness increased with the increase of [Hi] as well as α and achieved optimum solution at [Hi]=2.34D and α=20° respectively. The kidney-shaped vortex structure existing in the flow field have been damaged significantly with the increase of α.