Effect of Thermal Conductivity on Heat Transfer From a Flat Plate With Combined Impingement and Film Cooling

Abstract

The effect of solid thermal conductivity on conjugate heat transfer from a flat plate with combined impingement and film cooling is studied both experimentally and computationally. One side of the plate is exposed to hot mainstream, while the other side experiences impinging air jets. A geometric configuration with multiple staggered rows of cylindrical film holes and a matrix of impingement holes is considered. In the experiments a thermo-chromic liquid crystal (TLC) technique is used to measure the surface temperature. For the purpose of computations, the physical domain is meshed with very fine sized hexahedral and tetrahedral grids suitable for the finite volume method. Grid refinement is carried out using GCI method and SST κ-omega RANS equations are used for turbulence modeling. Three blade materials: A - with k = 0.2W/m K, B - with k = 1.5W/m K and C - with k = 15W/m K and three blowing ratios, M = 0.6, 1.0 and 1.6 are considered for the conjugate heat transfer study. A good agreement of effectiveness distribution on the interaction surface is found between the measured and the computations. On the interaction surface, heat flux values are the lowest for material A and progressively increase with increasing thermal conductivity. However the effectiveness values vary significantly for material A in the stream-wise direction. The Nusselt number on the other hand differs only slightly among different materials.