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PREDICTION OF THREE-DIMENSIONAL FLOW AND HEAT TRANSFER THROUGH RIBBED DUCTS USING A NON-LINEAR k-ε MODEL

Mehrdad Raisee
School of Mechanical Engineering, College of Engineering, University of Tehran, Center of Excellence in Design and Optimization of Energy Systems (CEDOES), Tehran, Iran

H. Naeimi
Department of Mechanical Engineering, Faculty of Engineering, University of Tehran, Tehran, Iran

Hector Iacovides
Turbulence Mechanics Group, School of Mechanical, Aerospace and Civil Engineering. The University of Manchester, Manchester M13 9PL, U.K.

Abstract

The present paper deals with the prediction of three-dimensional fluid flow and heat transfer in rib-roughened ducts of square cross-section. Such flows are of direct relevance to the internal cooling system of modern gas turbine blades. In this paper flow and thermal prediction of linear and non-linear k − ε models have been included. Both turbulence models have been used with the form of length-scale correction term to the dissipation rate originally proposed by Yap (1987) and also a differential version of this term, 'NYP'. The mean flow predictions show that both linear and non-linear k − ε models can successfully reproduce most of the measured data for stream-wise and cross-stream velocity components. Moreover, the non-linear model, which is sensitive to turbulence anisotropy, is able to produce better results for the turbulent stresses. Heat transfer comparisons show that the Nusselt number predictions obtained with the modified version of the nonlinear eddy-viscosity model proposed by Craft et al. (1999) (NLEVM2) and the 'NYP' length-scale correction term are in close agreements with the measured data.