Aerothermal performance of different relative positions of holes and ribs of a flat-plate film cooling hole with a straight-ribbed crossflow coolant channel

The integration of internally ribbed cooling channels with external film cooling is a widely adopted cooling technique for gas turbines. This study numerically investigated the effects of different relative positions of holes/ ribs on the flow and heat transfer characteristics of cylindrical film-cooling holes. Nine film-cooling hole position cases, two crossflow Reynolds numbers (Re = 200,000-600,000), and four blowing ratios (M = 0.5- 2.0) were considered. All cases used the ribbed crossflow supply method with a rib height of 0.4 D. We analyzed the change rule in the cooling performance and discharge coefficients with the relative positions of holes/ribs. In addition, we analyzed the mechanism contributing to relevant changes from the perspectives of the structure of the flow field inside and outside the holes, as well as the aerodynamic and heat transfer characteristics. The relative positions of the holes/ribs exerted a more pronounced impact at high crossflow Reynolds numbers. Across the entire range of operating conditions, positions 6 and 9 demonstrated the highest film-cooling performance and discharge coefficient, respectively. When the crossflow Reynolds number was relatively high and the blowing ratio was 1.0, the difference in the film-cooling efficiency between positions 6 and 8 was 45.9 %, which increased to 88.1 % at a blowing ratio of 2.0. Hence, the relative positions of film-cooling holes affect the degree to which the holes are affected by the crossflow, which consequently affects the flow-field structure and aerothermal properties. This research aids in achieving refinement and integration in the design of turbine blade cooling structures.