Turbulent flow and heat transfer in stationary and rotating cooling passages with inclined ribs on opposite walls

Abstract

Purpose

This paper aims to compute flow and heat transfer through a straight, orthogonally rotating duct, with ribs along the leading and trailing walls, in a staggered arrangement and at an angle of 45° to the main flow direction.

Design/methodology/approach

Flow computations have been produced using a 3D non‐orthogonal flow solver, with two two‐layer models of turbulence (an effective‐viscosity model and a second‐moment closure), in which across the near‐wall regions the dissipation rate of turbulence is obtained from the wall distance. Flow comparisons have been carried out for a Reynolds number of 100,000 and for rotation numbers of 0 (stationary) and 0.1. Temperature comparisons have been obtained for a Reynolds number of 36,000, a Prandtl number of 5.9 (water) and rotation numbers of 0 and 0.2 and also at a Prandtl number of 0.7 (air) and a rotation number of 0.

Findings

It was found that both two‐layer models returned similar flow and thermal predictions which are also in close agreement with the flow and thermal measurements. The flow and thermal developments are found to be dominated by the rib‐induced secondary motion, which leads to strong span‐wise variations in the mean flow and the local Nusselt number and to a uniform distribution of turbulence intensities across the duct. Rotation causes the development of stronger secondary motion along the pressure side of the duct and also the transfer of the faster fluid to this side. The thermal predictions, especially those of the second‐moment closure, reproduce the levels and most of the local features of the measured Nusselt number, but over the second half of the rib interval over‐predict the local Nusselt number.

Originality/value

The work contributes to the understanding of the flow and thermal development in cooling passages of gas turbine blades, and to the validation of turbulence models that can be used for their prediction, at both effective viscosity and second‐moment closure levels.

Citation

Iacovides, H. and Raisee, M. (2008), "Turbulent flow and heat transfer in stationary and rotating cooling passages with inclined ribs on opposite walls", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 18 No. 2, pp. 258-278. https://doi.org/10.1108/09615530810846374