Computations of Discrete-Hole Film Cooling Over Flat and Convex Surfaces

Abstract

Computations were performed to investigate the three-dimensional flow and heat transfer about a flat surface and a convex surface cooled by jets, injected from a plenum through one row of film-cooling holes inclined at 35° with a density ratio of 1.6 and mass flux ratios of 0.5 and 1.0. The focus is on understanding how the mainflow distorts the jets issuing from the film-cooling holes and how the resulting interactions affect film cooling effectiveness and temperature distribution. Results are presented for the surface adiabatic effectiveness, normalized temperature, velocity vector field, and contours of the vorticity magnitude. The computed results for the surface effectiveness on a flat plate were compared with experimental data, and reasonably good agreements were obtained. This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy closed by a low Reynolds number k-ω/SST turbulence model (i.e., wall functions were not used). Solutions were generated by a cell-centered finite-volume method that uses second-order accurate flux-difference splitting of Roe, multigrid acceleration of a diagonalized ADI scheme with local time stepping, and patched/overlapped structured grids. In the computations, the flow is resolved not just in the cooling-jet/mainflow interaction region, but also inside the film-cooling holes and in the plenum.