Turbulent flow and endwall heat transfer analysis in a 90° turning duct and comparisons with measured data - Part I: Influence of Reynolds number and streamline curvature on viscous flow development

This paper deals with the experimental and computational analysis of flow and heat transfer in a turning duct simulating the overall three-dimensional flow and heat transfer characteristics of gas turbine passages and internal cooling channels. The numerical results obtained for three different Reynolds numbers (790, 40,000, and 342,190) are compared to measured flow characteristics. Extensive measurements of the mean flow structure using a sub-miniature five-hole-probe and a hot-wire provide a quantitative assessment of the computational model used in the analysis. An in-house developed three-dimensional viscous flow solver is the main computational tool of the present study. A well known pressure correction method (SIMPLE) is used for the solution of 3-D incompressible, steady Navier-Stokes equations in a generalized coordinate system. The k-ε turbulence model of Launder and Spalding including a curvature correction scheme is utilized to describe the turbulent flow field. A non-staggered grid system is used in an upwind scheme with additional numerical dissipation terms. It is clearly shown that reducing the artificial dissipation terms in a central differencing scheme reduced the numerical dissipation error. Part II of this paper deals with the convective heat transfer aspects of the specific flow near the endwall surface where three-dimensional viscous flow structures are dominant. The measured fluid mechanics data presented in this paper also provide a reliable data set that can be used in the future validation of new computational methods.