Recent progress in the computation of flow and heat transfer in internal cooling passages of turbine blades

This paper describes our efforts to compute convective heat transfer throug h gas-turbine blade-cooling passages. The influence on the mean and turbule nt flow due to surface rib-roughness is the main focus. A number of turbule nce models, of effective viscosity (EVM) and second-moment type, are applie d to the computation of flow and heat transfer through ribbed-roughened pas sages. Computations of flow through a rib-roughened U-bend show that second moment closures are necessary in order to correctly reproduce the regions of flow separation. Heat transfer computations through two-and also three-d imensional ribbed passages reveal that low-Re turbulence models are necessa ry and that a low-Re differential stress closure yields thermal predictions that are superior to those of the low-Re EVM model. A differential version of the Yap length-scale correction term, independent of the wall distance, is introduced to the dissipation rate equation and is found to improve the heat transfer predictions of the low-Re k-epsilon model. (C) 1999 Elsevier Science Inc. All rights reserved.