Conjugate Heat Transfer From a Flat Plate With Combined Impingement and Film Cooling

Computational and experimental investigations are reported on a flat plate subjected to combined impingement and film cooling with a (14 × 14) matrix of impingement holes and three (6 × 4) staggered arrays of 35° inclined film holes. Conjugate flow and thermal computations are carried out, by using shear stress transport (SST) κ-ω turbulence model. The combined thermo fluid dynamic features of impinging jets and the coolant-mainstream interactions in presence of impingement and film cooling plates are described. Local values of Nusselt number are presented on the impingement surface and film cooling effectiveness values are plotted along the interaction surface. The computed surface temperature distribution is validated by thermochromic liquid crystal measurements. A comparison between the film cooling and the combined impingement and film cooling shows that the surface effectiveness values for the combined cooling are higher as well as more uniform. As the blowing ratio is increased from M = 0.6 to 1.0, the local streamwise effectiveness values show an increasing trend for both the cases. The effectiveness values are higher for higher conducting material at all blowing ratios. However, in case of lower conducting material, local patches of higher effectiveness are observed close to the jet exit.