逆压力梯度下几何参数对气膜冷却效率的影响

采用放大模型在低速回流式风洞中进行了实验,研究了逆压力梯度下圆柱形孔、扇形孔和双向扩张形孔的气膜冷却效率,分析了孔间距、前倾角和径向角等几何参数对气膜冷却效率的影响.结果表明:扇形孔的气膜冷却效率最大,双向扩张形孔次之,圆柱形孔最小.孔间距越小,气膜冷却效率越大,且动量比越小,孔间距的影响越大.前倾角越小,气膜冷却效率越大,动量比越大,前倾角的影响越大.径向角的影响较复杂,小于30°且递增时,气膜冷却效率随动量比的增大而减小;大于30°时,气膜冷却效率随径向角的增大而减小. 

Influence of geometric parameters on film cooling effectiveness under adverse pressure gradient

To study film cooling effectiveness of cylindrical hole, fanned hole and bidirectional expanded hole, as well as influence of hole pitches, plane angles, radial angles on film cooling effectiveness, experiments were performed in a low speed closed-looped wind tunnel with scale-up model. The experimental results show that the film cooling effectiveness of fanned hole is the most one, that of bidirectional expended hole is the second one, and that of cylindrical hole is the least one. The decreasing of hole pitches lead to the increased of film cooling effectiveness, and the smaller the momentum ratio is, the stronger the influence of hole pitch on film cooling effectiveness is. The decreasing plane angles lead to the increased film cooling effectiveness. The influence of plane angles on film cooling effectiveness increases with the increasing momentum ratios. Influence of radial angles is complex. When they are less than 30° and are increasing, the decreasing film cooling effectiveness result from the increased momentum ratios. While they are more than 30°, the increasing radial angles result in the decreased film cooling effectiveness.