Analysis of film cooling performance of advanced tripod hole geometries with and without manufacturing features

The present study evaluates the film cooling performance of a set of manufacturable tripod hole designs, with and without shaped exits. The tripod holes with realistic manufacturing features included rounded corners at the hole inlet and outlet, as well as a webbing between the tripod holes. Standard cylindrical and shaped cylindrical (10° fan + laidback) holes were also studied for comparative analysis. Transient heat transfer experiments with a mainstream Red ≈ 3200 were conducted on a flat plate test rig. Different hole geometries were tested at equal mass flow rates, corresponding to a range of blowing ratios equal to 0.5, 1.0, and 2.0 for the cylindrical hole. IR (Infrared) thermography was used to evaluate adiabatic film cooling effectiveness, heat transfer coefficient, and the normalized heat flux on the flat surface. Results showed that the presence of rounded corners or webbing did not lower the performance of the tripod cooling holes. Both tripod hole geometries, with and without manufacturing features, yielded higher film cooling effectiveness compared to the cylindrical holes and slightly higher effectiveness than the shaped holes, while consuming 50% less coolant when operating at the same blowing ratio. Furthermore, the heat transfer coefficient measurements and the overall heat flux ratios further corroborated the thermal advantages of the tripod hole design over traditional cylindrical and shaped holes.