Investigations of film cooling and heat transfer on a turbine blade squealer tip

Abstract

At three tip gap sizes, two kinds of cooling-hole distributions and three blowing ratios, heat transfer coefficient and adiabatic film cooling effectiveness on a blade squealer tip with cooling holes were numerically computed and also validated with the experimental data. The results showed that, for the squealer tip configured with only tip cooling holes, a lower heat transfer coefficient area can be achieved near the pressure side of cavity floor as increasing the blowing ratio. As tip clearance increases, the area-averaged heat transfer coefficient on the squealer tip is increased. While the film cooling effectiveness near the pressure side of the cavity floor is decreased due to less coverage of coolant. For the squealer tip configured with both tip and pressure-side holes, coolant ejection from the pressure side holes can effectively cool the squealer rim, tip trailing edge, and cavity floor near the pressure side. As the blowing ratio or tip clearance increases, heat transfer coefficients on the cavity floor near pressure side, squealer rim and tip trailing edge decrease significantly, while the adiabatic film cooling effect on these areas are enhanced, significantly.