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

The computation of high-lift flows poses considerable challenges to the aerodynamicist.The work presented in this thesis describes the development ofan efficient unstructured grid generation method for high lift flows and theapplication of Differential Reynolds Stress Models (DRSM).The method described in this thesis, separates the grid generation processinto two steps: generation of the anisotropic regions and isotropic grid generation.All surfaces are triangulated as part of the anisotropic grid generationprocess. The user can also specify the wake regions. Using surfaces or wakes,the algorithm computes the normals to the surfaces and distributes new pointsalong those directions. This initial grid is connected to the outer boundaries.The cells connecting the anisotropic grid with the outer boundaries are continuouslyrefined using an edge-splitting algorithm that creates new computationalcells, grid points and cell connectivities simultaneously.The second part of this research involves the assessment of two DRSMagainst a k — e model. The validation study included the Launder-Rodi-Reece(LRR) DRSM and the Speziale-Sarkar-Gatski (SSG) DRSM. The ReynoldsaverageNavier-Stokes (RANS), are solved explicitly using a cell centred finitevolumescheme.The focus of the validation study, are high-lift configurations tested as partof the U.K. National High-Lift Programme. The aerofoils considered include a3, 4 and 5-element configuration, designated NHLP L1/T2, NHLP L1/T7 andNHLP L1/T8 respectively.The results for the L1/T2 and L1/T7 aerofoils show only marginal differenceson the predicted aerodynamic loads. The results for the L1/T8 showsignificant differences between both types of models, with the LRR exhibitingthe closest agreement with experimental data. Results indicate that only in these extreme cases, the advantages of a Differential Reynolds Stress Modelinfluence the aerodynamic loads results. However in most cases the DRSMsproduced a better representation of the flow physics.

Level dc:type.qualificationlevel

Doctoral (Level 8)

Year dc:date.issued

2008

Author dc:creator

• Marques, SP

Language dc:language

en

Identifier

oai:salford-repository.worktribe.com:1337057

OAI identifier oai:identifier

oai:salford-repository.worktribe.com:1337057