This study experimentally investigated the effects of geometric parameters of an inclined slot on film cooling effectiveness (FCE) and proposed an optimal slot configuration using a Kriging model. The experiment was designed using the Box–Behnken design, incorporating three geometric parameters—the injection angle (α), inlet edge fillet radius (RL,in), and outlet edge fillet radius (RL,out)—at four blowing ratio conditions (M = 0.25, 0.5, 1.0, and 2.0). The FCE distributions were measured on a flat plate test section using the pressure sensitive paint technique, with a mainstream velocity of 30 m/s and a turbulence intensity of 12% conditions. The results showed that the injection angle was the dominant factor governing cooling performance, as 30° inclined slots consistently exhibited higher FCE than those of 60° inclined slots, regardless of edge geometry. The inlet edge fillet radius had little influence at low blowing ratios but became significant at higher ratios when combined with a large outlet fillet radius. The outlet edge fillet radius demonstrated a dual effect—moderate shaping improved near-exit coverage, whereas excessive shaping enlarged the exit area, reduced jet momentum, and lowered FCE downstream. The Kriging optimization predicted the optimal slot configurations for each blowing ratio, all featuring an injection angle of 30°. Results of validation tests showed that FCE was enhanced by ∼28% over the baseline.
Kim et al. (Thu,) studied this question.