A numerical investigation into the enhancement of cooling efficiency in Double-Wall configurations incorporating droplet-shaped hollow pin-fins

Double-wall cooling offers significant advantages for turbine vane thermal protection owing to its superior cooling effectiveness. This paper proposes a double-wall configuration incorporating droplet-shaped hollow pin-fins to simultaneously enhance overall cooling performance and reduce flow loss. The heat transfer characteristics and flow loss of the conventional double-wall configuration and the proposed configuration are numerically investigated under various blowing ratios. Positioning the droplet-shaped hollow pin fins adjacent to the film holes mitigates vortex intensity through a vortex-cancellation mechanism, thereby improving film coverage. The proposed configuration achieves a 100.6% increase in surface-averaged film cooling effectiveness compared with the conventional double-wall configuration at M = 1.0. Meanwhile, the enlarged heat transfer area provided by the droplet-shaped pin fins enhances internal cooling performance, resulting in a 17.4% increase in the overall Nusselt number at M = 1.0. Furthermore, the proposed configuration exhibits a 36.9% enhancement in surface-averaged overall cooling effectiveness at M = 0.4. In addition, the incorporation of droplet-shaped hollow pin fins reduces the total pressure drop during coolant discharge. The proposed configuration exhibits superior flow-loss reduction capability, with the coolant discharge coefficient improved by up to 41.2% at M = 1.0. Owing to its excellent thermo-fluid performance, the proposed configuration shows strong potential for next-generation turbine blade cooling applications.