Analysis of flow characteristics and cooling performance of a novel impingement/effusion structure with bypass hollow holes

Abstract

As a promising cooling technique, the double-wall cooling structure has been integrated into the design of advanced aeroengine high-temperature components. However, its widespread application in configurations with low pressure ratios between secondary flow and the main flow is hindered due to significant internal flow resistance. To address this issue, a novel low-resistance hollow pillar double-wall structure (NHDW) is developed. This study conducts conjugated heat transfer numerical simulations of NHDW and the traditional solid pillar double-wall structure (TSDW) for comparative analysis. Flow characteristics are examined to understand the sources of internal flow resistance and the coupling mechanism between internal and external heat transfer. The results demonstrate that the NHDW exhibits substantially lower flow resistance than the TSDW, with the total pressure loss dropping to approximately 1/3 of the corresponding TSDW under hole inclination angles of 30°, 60°, and 90°. The reduced internal flow resistance of the NHDW is attributed to the parallel bypass flow within the hollow pillar. Moreover, the overall cooling effectiveness (ϕ) of NHDW is enhanced by 9.2%–16.9% for different inclination angles at a blowing ratio of M = 1.0. Additionally, the interaction vortex structure on the mainstream side surface of the NHDW significantly improves the external cooling effectiveness, contributing to the overall enhancement of the cooling performance. Furthermore, a one-dimensional thermal resistance analysis method is introduced to distinguish the contributions of internal cooling and external film cooling. This analysis highlights the importance of external cooling enhancements in the novel structure.