Influence of Typical Injection Parameters on Film Cooling Performance

Modern aero-engines and gas turbines pursue higher thermal efficiency by elevating turbine inlet temperatures, which imposes stringent thermal protection requirements on turbine blades. This study numerically investigates composite film-cooling performance under varying blowing ratios and film-hole-to-impingement-hole diameter ratios, focusing on flow characteristics and the evolution of cooling effectiveness. The results indicate that a higher blowing ratio enhances the trench-induced anti-kidney vortex pair, suppresses the lift-off of the kidney vortex pair, and thereby improves film coverage and spatially averaged cooling effectiveness. However, an excessive blowing ratio yields marginal performance improvement owing to intensified coolant–mainstream mixing. In contrast, the diameter ratio modulates the initial film flow patterns through varying impingement intensity; cooling effectiveness exhibits a typical unimodal trend, with an optimal value at D/Dj = 1.5. This work provides a feasible technical reference for thermal protection and optimized film-cooling design of turbine components.