Computation of high-lift aerodynamics using unstructured grids and Reynolds-stress turbulence models

Marques, SP 2008, Computation of high-lift aerodynamics using unstructured grids and Reynolds-stress turbulence models , PhD thesis, University of Salford.

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Abstract

The computation of high-lift flows poses considerable challenges to the aerodynamicist. The work presented in this thesis describes the development of an efficient unstructured grid generation method for high lift flows and the application of Differential Reynolds Stress Models (DRSM). The method described in this thesis, separates the grid generation process into two steps: generation of the anisotropic regions and isotropic grid generation. All surfaces are triangulated as part of the anisotropic grid generation process. The user can also specify the wake regions. Using surfaces or wakes, the algorithm computes the normals to the surfaces and distributes new points along those directions. This initial grid is connected to the outer boundaries. The cells connecting the anisotropic grid with the outer boundaries are continuously refined using an edge-splitting algorithm that creates new computational cells, grid points and cell connectivities simultaneously. The second part of this research involves the assessment of two DRSM against a k — e model. The validation study included the Launder-Rodi-Reece (LRR) DRSM and the Speziale-Sarkar-Gatski (SSG) DRSM. The Reynoldsaverage Navier-Stokes (RANS), are solved explicitly using a cell centred finitevolume scheme. The focus of the validation study, are high-lift configurations tested as part of the U.K. National High-Lift Programme. The aerofoils considered include a 3, 4 and 5-element configuration, designated NHLP L1/T2, NHLP L1/T7 and NHLP L1/T8 respectively. The results for the L1/T2 and L1/T7 aerofoils show only marginal differences on the predicted aerodynamic loads. The results for the L1/T8 show significant differences between both types of models, with the LRR exhibiting the closest agreement with experimental data. Results indicate that only in these extreme cases, the advantages of a Differential Reynolds Stress Model influence the aerodynamic loads results. However in most cases the DRSMs produced a better representation of the flow physics.

Item Type: Thesis (PhD)
Contributors: Johnston, LJ (Supervisor)
Schools: Schools > School of Computing, Science and Engineering
Funders: Engineering and Physical Sciences Research Council (EPSRC)
Depositing User: Institutional Repository
Date Deposited: 18 Aug 2021 14:39
Last Modified: 27 Aug 2021 21:57
URI: http://usir.salford.ac.uk/id/eprint/61623

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