Convective heat transfer enhancement in a turbine blade channel with dimple, rib and hybrid rib-dimple structures

The present study numerically investigates the flow and heat transfer characteristics in a roughened coolant channel with a 4:1 aspect ratio pertinent to modern gas turbine (GT) blade cooling. Three structural configurations: hybrid V-ribs with spherical-dimples, standalone spherical-dimples, and standalone V-ribs are analyzed for various Reynolds numbers. Simulations are performed to investigate the effects of different geometric arrangements and operational variables relevant to the actual GT blade channels used in aviation industries. The standalone spherical-dimples generate recirculating vortices, while standalone V-ribs produce weak longitudinal vortices. In contrast, the hybrid V-rib and spherical-dimple configuration develops stronger longitudinal vortex pairs, enhancing turbulence mixing and promoting more uniform heat transfer. The highest heat transfer zones shift, with the hybrid configuration achieving a normalized Nusselt number of 2.55–8.40% and 21.39% higher than the standalone V-rib and spherical-dimple configurations. While increasing dimple depth initially boosts heat transfer, excessive depth leads to coolant stagnation and reduced heat transfer efficiency. The hybrid rib-dimple configuration achieves up to 54.13% enhancement in heat transfer, resulting in a 36.23% decrease in thermal–hydraulic performance. The results indicate that the hybrid rib-dimple arrangement significantly improves heat transfer while maintaining an acceptable pressure drop for GT blade cooling applications.