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Transition and heat transfer predictions in a turbine cascade at various free‐stream turbulence intensities through a one‐equation turbulence model
Author(s) -
Tsourakis G. I.,
Koubogiannis D. G.,
Giannakoglou K. C.
Publication year - 2002
Publication title -
international journal for numerical methods in fluids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 112
eISSN - 1097-0363
pISSN - 0271-2091
DOI - 10.1002/fld.262
Subject(s) - turbulence , k omega turbulence model , k epsilon turbulence model , turbulence modeling , mechanics , reynolds stress equation model , boundary layer , reynolds number , reynolds decomposition , cascade , nozzle , physics , mathematics , thermodynamics , engineering , chemical engineering
The one‐equation Spalart–Allmaras turbulence model, coupled with criteria for the prediction of the transition onset, is employed for the numerical prediction of the heat transfer along the nozzle guide vanes of a high‐pressure turbine, at various operating conditions. Emphasis is put on how to overcome a known shortcoming of the Spalart–Allmaras model, i.e. its insensitivity to free‐stream turbulence. For this purpose, an extra viscosity coefficient is defined and used in the mean flow equations. This extra viscosity is proportional to the free‐stream turbulence with a damping in the boundary layer. Its use is adequate to circumvent the aforementioned weakness of the Spalart–Allmaras model, without any other intervention in the model itself. For the prediction of the onset of transition, the Abu‐Ghannam and Shaw and the Mayle criteria are used, depending on the level of free‐stream turbulence. Both yield very satisfactory predictions in a wide range of Reynolds numbers and/or turbulence intensities. From a numerical point of view, this paper proposes techniques for the implementation of the solution method on unstructured grids with triangular elements and reconfirms findings of previous works, like the suitability of the containment‐circle tessellation in highly stretched grids. Copyright © 2002 John Wiley & Sons, Ltd.