Orthogonal experimental study on the cooling performance of a effusion flat-plate film cooling structure considering structural and aerodynamic parameters

To address the challenges of limited cooling airflow and significantly increased wall heat flux in high-temperature combustion chambers of advanced military aircraft engines, this study systematically investigates the coupled effects of multiple structural and aerodynamic parameters on the cooling characteristics of a effusion flat-plate film cooling structure. An orthogonal experimental design method was employed to examine the impacts of four structural parameters—hole diameter, hole spacing ratio, tangential hole inclination angle, and wall thickness —on cooling efficiency and flow coefficient. Based on this, a structural configuration with optimal comprehensive performance was selected for further aerodynamic parameter tests under varying blowing ratios and heating ratios. Wall temperature distributions and critical heat flux parameters were obtained using infrared thermography and thermocouples. The range analysis revealed that the most significant structural parameters affecting cooling efficiency are the hole spacing ratio and hole diameter, both of which exhibit a negative correlation with cooling efficiency. For the flow coefficient, the hole diameter is the dominant factor, showing a positive correlation, thus highlighting the trade-off between cooling performance and flow performance. Aerodynamic parameter tests demonstrated that for the optimized structure, when the blowing ratio increased from 2 to 5, the cooling efficiency in the downstream stable region improved significantly from approximately 0.70 to 0.77. Conversely, when the heating ratio increased from 2 to 3, the cooling efficiency decreased from about 0.70 to 0.66. Reducing the hole diameter and spacing is the most effective structural optimization approach to enhance effusion cooling efficiency but requires a trade-off with its negative impact on the flow coefficient. Once the structure is determined, appropriately increasing the blowing ratio serves as a critical aerodynamic control measure to counteract rising mainstream temperatures (increased heating ratio) and maintain wall cooling effectiveness. The study provides experimental data and engineering guidance for the design and optimization of high-performance combustion chamber cooling structures.