Heat transfer and film cooling effectiveness on the squealer tip of a turbine blade

Abstract

Detailed heat/mass transfer coefficients and film-cooling effectiveness were measured on the tip and inner rim surfaces of a blade with a squealer rim. The test blade was a two-dimensional version of a modern first-stage gas turbine rotor blade with a squealer rim. The experimental apparatus was equipped with a linear cascade of three blades, and the axial chord length (Cx) was 237 mm with a turning angle of 126°, the mainstream Reynolds number based on the axial chord and inlet velocity was 1.5 × 105. In addition, three different types of blade tip surfaces were equipped with a single row of film-cooling holes along the camber line, near the pressure and suction-side rim. The blowing ratio was fixed at 1.5. High heat transfer rates were observed near the leading edge on the tip surface due to reattached flow. Furthermore, heat transfer on both inner side surfaces was higher than that on the tip surface. High film cooling effectiveness was observed in the middle region (0.1 < X/Cx < 0.6) due to stagnation of the film cooling. Ultimately, a proper cooling system is suggested to reduce the thermal load and enhance the film cooling effectiveness in the squealer tip.