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 influences of hole pitches,plane angles and 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 maximum,followed by that of bidirectional expended hole and cylindrical hole.The decrease of hole pitches leads to the increase of film cooling effectiveness,and the smaller the momentum ratio means stronger influence of hole pitch on film cooling effectiveness.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 results from the increased momentum ratios;when they are more than 30°,the decreasing film cooling effectiveness results from the increasing radial angles.