Numerical investigation of adiabatic film cooling effectiveness through compound angle variations

Abstract

Provided are numerically predicted distributions of film cooling effectiveness for single cylinder film holes and for single 15° forward diffused film cooling holes, with compound angles ranging from 0° to 180°. Hole inclination angle, with respect to the test surface, is 35° for all arrangements considered, and blowing ratios of 0.60 and 1.25 are used. Also presented are local flow secondary flow vector distributions, local flow streamwise vorticity distributions, and local variations of flow film cooling effectiveness. Significantly different variations of local and spatially-averaged film cooling effectiveness are evident from these results, as the magnitude of compound angle is altered. Of particular importance are the reduced tendencies for lift-off of coolant concentrations when the forward diffused holes are employed. As a result, overall, the most optimal thermal protection, associated with higher magnitudes of surface adiabatic film cooling effectiveness, is given by forward diffused holes at the higher blowing ratio of 1.25.