Film cooling performance on rotating-blade pressure side with three-row film holes at different incidence angles

Abstract

Different incidence angles mean the different flow fields in the blade channel, resulting in the different film cooling performance on the blade surface. This study experimentally measures the cooling effectiveness on the rotating-blade pressure side at positive, zero, and negative incidence angles (corresponding to 421 rpm, 600 rpm, and 691 rpm). The film cooling distributions obtained by the pressure-sensitive paint technique for three blades with different compound angles (0°, 45°, and −45°) under different blowing ratios (0.3–2.0) are presented. The results show that the stagnation line shifts to the pressure side and the deflection angle of the film trajectory is larger at the positive incidence angle. The stagnation line shifts to the suction side and the cooling jet near the leading edge flows vertically upward at the negative incidence angle. The cooling effectiveness for the negative compound angle (−45°) is reduced at the positive incidence angle. For blades with compound angles (−45° and 45°), the cooling effectiveness downstream of the pressure side varies little at the negative incidence angle.