Author(s)

O. Labbé

Abstract

Large-eddy simulation is used to understand the flow in a square ribbed duct representative of systems designed for internal cooling of turbine blades. The presence of ribs increases turbulence levels and enhances heat transfer. The objective of the present LES study is to solve three-dimensional Navier-Stokes equations for a compressible flow to enable simulations for which the temperature variation within the flow is very significant. This simulation allows us to deal with a fully developed turbulent flow and heat transfer in a ribbed channel with a high blockage ratio, whose parameters are chosen to reproduce the experiments of Casarsa et al. \“Characterization of the velocity and heat transfer fields in an internal cooling channel with high blockage ratio.” Proceedings of ASME TURBO EXPO 2002 June 3-6, Amsterdam, The Netherlands, 2002. The simulation is restricted to one pitch length and periodic conditions are applied in the streamwise direction. Mean and turbulent quantities are presented, together with the heat transfer. Keywords: LES, turbulence, heat transfer, rib, compressible flow. 1 Introduction The efficient design of the internal ducts in gas turbine blades requires a detailed knowledge of the flow and heat phenomena occurring inside these passages. In ducts, ribs are used to disturb the boundary layers, thereby promoting turbulence and enhancing heat transfer. The presence of the ribs leads to a complex velocity field with regions of flow separation upstream and downstream of the ribs and contributes to the level of mixing of the cooler part of the air stream with the warmer air close to the walls. A large number of experimental investigations are available in the literature on aerodynamics and heat transfer performance of internal cooling channels with

Keywords

LES, turbulence, heat transfer, rib, compressible flow.