Abstract
This study focuses on the prediction of the flow and thermal development through internal cooling passages with rib-roughened surfaces, using high-Reynolds-number models of turbulence. Such flows are relevant to internal blade cooling applications. The objective is to establish how reliably high-Re models, which are more economical to use than low-Reynolds-number versions, can predict the flow and thermal evelopment. Three test cases have been computed, for which experimental data are available for comparison: a twodimensional channel with square ribs on one wall, a duct of square cross-section with square ribs on two opposite walls in staggered arrangement and normal to the flow and a duct of square cross-section with square ribs on two opposite walls in in-line arrangement and normal to the flow direction. A general geometry code was employed, using non-orthogonal body fitted grids. Two turbulence models have been employed, an effective-viscosity k- model and also a second-moment differential stress model. In both cases the conventional wall-function strategy has been adopted, which relies on the log-law approximation. For the second-moment closure two versions of the wall-function have been tested, one in which the normal stresses at the near-wall nodes are prescribed as fixed proportions of the turbulent kinetic energy, and on in which these normal stresses are obtained from the solution of separate transport equations, suitably modified for the wall proximity. The flow development is well predicted by both models. Nusselt number comparisons show greater deviations between predictions and measurements. The second-moment closure, with both wall-functions, is shown to consistently improve the thermal predictions.
Original language | English |
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Title of host publication | UK Heat Transfer 2007 |
Publication status | Published - Sept 2007 |
Event | UK Heat Transfer 2007 - Duration: 1 Jan 1824 → … |
Conference
Conference | UK Heat Transfer 2007 |
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Period | 1/01/24 → … |