Investigation of the cooling characteristics of a Low-Resistance Double-Wall configuration with hollow Pin-Fins

Abstract

Due to its superior cooling performance, the double-wall structure has become a critical technology for extending the service life of high-temperature components in aeroengines. However, its high flow resistance poses a significant challenge to its application in turbine vanes. This study introduces an innovative double-wall structure incorporating hollow pin-fins to reduce flow resistance and enhance cooling performance. Numerical simulations are conducted to compare this novel structure with traditional double-wall and single-wall configurations. Additionally, the film hole shape of the optimal cooling structure is modified to a laid-back fan shape for further performance improvements. The simulations employ the RANS model, using the SST k-ω turbulence model. Key performance metrics, including the coolant flow coefficient, film cooling effectiveness, target plate Nusselt number, and overall cooling effectiveness, are evaluated for different cooling structures. The results demonstrate a significant reduction in flow resistance for the novel design, as the addition of hollow pin-fins facilitates a coolant outflow mechanism similar to that of a single-wall structure. The novel double-wall design reduces the flow coefficient by 5.4% compared to the single wall. In terms of cooling performance, the hollow pin-fins positioned on the spanwise sides of the film holes help prevent film detachment at high blowing ratios, while the pin–fin in the impingement chamber increases the internal heat transfer surface area. Overall, the cooling effectiveness of the novel design improves by up to 4.6% compared to the traditional double-wall structure. When laid-back fan-shaped holes are applied to the novel double-wall structure, further reductions in flow resistance and enhancements in cooling performance are observed. The increased channel area allows for a 6.7% increase in the flow coefficient compared to the single wall. Moreover, the double-wall structure with laid-back fan-shaped holes significantly enhances film adhesion, leading to a 70.0% improvement in film effectiveness and a 15.9% increase in overall cooling effectiveness compared to traditional double-walls.