Numerical investigation on the flow and heat transfer characteristics of impingement cooling in narrow channels under the influence of film hole aspiration

Double-wall cooling structures in modern turbine blades demand increasingly refined design as the coupling between impingement and film-cooling elements intensifies. Yet the mechanism by which film-hole suction alters the impingement-cooling flow field remains insufficiently understood. This work presents a numerical investigation of jet-impingement cooling subjected to film-hole suction, examining how film-hole layout, jet Reynolds number (Re j ), and jet-to-target distance ( h/d ) govern the internal flow and heat transfer of the “impingement–film” system. Film-hole suction rapidly evacuates the spent coolant after impingement, substantially weakening the crossflow-induced shear and deflection of downstream jets; this improves the spatial uniformity of target-surface heat transfer and raises overall heat transfer intensity by 7 %–10 %. The enhancement is greatest when film holes and jet holes are arranged in a staggered configuration. Increasing Re j thins the thermal boundary layer and augments turbulent kinetic energy (TKE), producing a secondary heat transfer peak away from the stagnation zone. Varying h/d from 0.5 to 4 allows more complete jet development and stronger mixing between the coolant and the ambient medium, raising relative thermal efficiency by up to 20 %. From a mechanistic perspective, heat transfer in the stagnation region is jointly affected by velocity gradient and temperature gradient, while heat transfer in the wall jet region is dominated by turbulent kinetic energy (TKE). Film-hole suction modulates both the spatial extent and intensity of these two mechanisms by reshaping the flow field.