Prediction of turbulent flow and local heat transfer in internally cooled turbine airfoils: the leading edge region

Abstract

A multiblock numerical method has been employed for the calculation of three-dimensional flow and heat transfer in the leading edge of a large-scale impingiment-cooled turbine airfoil. The finite-analytic method solves the Reynolds-Averaged Naviers-Stokes equations and the energy equation in conjunction with a two-layer K-Epsilon isotropic eddy viscosity model and a near-wall Reynolds-Stress closure model. The fundamental cases of fully developed turbulent pipe flow and an axisymmetric jet impinging on a flat plate are also computed and compared with experimental data to asses the two turbulence models. Comparison of the two-layer model and the Reynolds-Stress model calculations clearly shows the anisotropic behavior of turbulence resulting from impingiment. The predicted flow field showed flow separation and recirculation after impingiment on the leading edge region. The predicted local heat transfer distribution on the leading edge of the turbine blade shows a maximum near the stagnation region with a gradual decrease in Nusselt number in the spanwise direction.