The influence of rotating speed on film cooling characteristics on GE-E3 blade tip with different tip configurations

The film cooling phenomenon of flat tip (with or without a trench) and squealer tip on GE-E3 blade in rotating state was numerically studied. The effect of tip configuration, rotating speed and blowing ratio on the blade tip flow and cooling performance was revealed. It was found that the squealer tip and the flat tip with trenched hole have comparability in configuration: both have a cavity at the end of the film hole. So the coolant momentum and the tip leakage flow velocity in the cavity are decreased, which contributes to the improvement of the cooling effect. Because of the bigger cavity of the squealer tip than that of the flat tip with trenched hole, the cooling air and the leakage flow mix adequately in the cavity, the squealer tip can get the highest cooling effectiveness and the lowest heat transfer coefficient value both in stationary and rotating state, and the flat tip with trenched hole follows. With the increase of rotating speed, for all the three configurations, the area-averaged cooling effectiveness decreases and the area-averaged heat transfer coefficient increases. At the same time, the tip leakage flow entraps the cooling air moving toward the leading edge. And with the increase of the blowing ratio, for all the configurations, the area-averaged cooling effectiveness increases while the area-averaged heat transfer coefficients decreases.