Enhancing turbine vane cooling design using hollow pin-fins: Flow resistance and cooling characteristics

Existing double-wall cooling structures and their optimized configurations suffer from high flow resistance. This hinders the discharge of coolant and also induce hot gas ingestion, thereby severely restricting their application in aero-engine turbine cooling. In the present study, hollow pin-fins are introduced into the double-wall structure, enabling it to achieve both low flow resistance and high cooling effective, and the design is applied to a turbine vane. Numerical simulations under conjugate heat transfer conditions are conducted for a turbine vane with complex cooling configurations using the Reynolds averaged Naiver-Stokes method. The coolant flow distribution, discharge coefficient, and both internal and external cooling performance are analyzed under different hole types and coolant flow conditions. The novel double-wall structure exerts the most significant influence on the coolant redistribution in the front-cavity. In this case, the coolant is mainly discharged through the double-wall from both the suction and pressure surfaces, and the discharge coefficient is increased. When the hole type is adjusted to a 7-7-7 shaped hole, the outlet flow area is enlarged, effectively reducing the flow resistance of the coolant. Due to the coolant redistribution effect induced by the hollow pin-fins, the amount of coolant available for impingement cooling is reduced, and the internal cooling performance still exhibits a certain degree of reduction. However, the synergistic effect between the hollow pin-fins and film holes suppresses vortices and enhances film adherence on the vane surface. As a result, the external cooling performance is significantly improved. The combined cooling performance indicates that the novel double-wall structure can still achieve higher overall cooling effectiveness while balancing both internal and external cooling. The maximum vane surface temperature reduction reaches up to 50 K, demonstrating outstanding integrated performance.