EFFECTS OF LEADING EDGE SHAPE ON EFFUSION FILM COOLING

This study investigated effusion film cooling on turbine leading edge model using pressure sensitive paint (PSP) technique. Three leading edge profiles were tested, including a semi-cylinder and two elliptical leading edge models. Effusion cooling was implemented using a large number of holes with small hole-to-hole spacing, and Stereolithography was used to produce the perforated region. Effects of blowing ratio (0.4, 0.8, and 1.2) were tested and the density ratio was maintained at unity. Three rows of film cooling holes were employed on these leading edge models as a traditional film cooling scenario for benchmark testing. These film cooling rows exhibited 15 holes, located at the stagnation line (0°) and at ±30° away from the stagnation line. These test models were installed in a low-speed wind tunnel for testing. The Reynolds number was 100,000, which was estimated using the mainstream velocity and semi-cylinder diameter. Two streamwise spacings of the effusion holes were studied. The effusion cooling showed higher cooling effectiveness compared to the traditional film cooling. Increasing the streamwise spacing lowered the cooling effectiveness regardless of the leading edge profile. The variation of the blowing ratio had smaller effect on the effusion cooling effectiveness and coolant blow-off was not substantial.