Film Cooling Performance of Cylindrical Holes Embedded in a Transverse Trench

The film cooling performance of cylindrical holes embedded in a transverse trench is evaluated for various shapes of the trench and blowing ratios, and an optimum geometry for the trenched film-cooling hole is suggested. In order to analyze the turbulent flow and film cooling performance, three-dimensional Reynolds-averaged Navier-Stokes analysis is performed using the shear stress transport turbulence model. Tetrahedral and hexahedral computational meshes are tested, and the numerical solution is validated by comparison with experimental data. A parametric study with two geometric variables, the height and width of the trench, is performed. From the results of the parametric study and flow field analysis, shifting the film cooling hole toward the upstream end of the trench is proposed to enhance film cooling performance. In addition, the optimum downstream trench width is determined.