Journal article · Conference paper
Discontinuous Galerkin methodology for Large-Eddy Simulations of wind turbine airfoils
This paper aims at evaluating the potential of the Discontinuous Galerkin (DG) methodology for Large-Eddy Simulation (LES) of wind turbine airfoils. The DG method has shown high accuracy, excellent scalability and capacity to handle unstructured meshes. It is however not used in the wind energy sector yet.
The present study aims at evaluating this methodology on an application which is relevant for that sector and focuses on blade section aerodynamics characterization. To be pertinent for large wind turbines, the simulations would need to be at low Mach numbers (M ≤ 0.3) where compressible approaches are often limited and at large Reynolds numbers (Re ≥ 106) where wall-resolved LES is still unaffordable.
At these high Re, a wall-modeled LES (WMLES) approach is thus required. In order to first validate the LES methodology, before the WMLES approach, this study presents airfoil flow simulations at low and high Reynolds numbers and compares the results to state-of-the-art models used in industry, namely the panel method (XFOIL with boundary layer modeling) and Reynolds Averaged Navier-Stokes (RANS).
At low Reynolds number (Re = 6 × 104), involving laminar boundary layer separation and transition in the detached shear layer, the Eppler 387 airfoil is studied at two angles of attack. The LES results agree slightly better with the experimental chordwise pressure distribution than both XFOIL and RANS results.
At high Reynolds number (Re = 1.64 × 106), the NACA4412 airfoil is studied close to stall condition. In this case, although the wall model approach used for the WMLES is very basic and not supposed to handle separation nor adverse pressure gradients, all three methods provide equivalent accuracy on averaged quantities.
The present work is hence considered as a strong step forward in the use of LES at high Reynolds numbers.
Language: | English |
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Publisher: | IOP Publishing |
Year: | 2016 |
Pages: | 022037 |
Proceedings: | The Science of Making Torque from Wind 2016European Academy of Wind Energy : The Science of Making Torque from Wind |
ISSN: | 17426596 and 17426588 |
Types: | Journal article and Conference paper |
DOI: | 10.1088/1742-6596/753/2/022037 |
ORCIDs: | Sørensen, Niels N. |
Applied fluid mechanics DG methodology Eppler 387 airfoil Fluid mechanics and aerodynamics (mechanical engineering) Galerkin method General fluid dynamics theory, simulation and other computational methods LES methodology Mach numbers Mechanical components Navier-Stokes equations Numerical analysis Numerical approximation and analysis Power and plant engineering (mechanical engineering) RANS Reynolds averaged Navier-Stokes Reynolds numbers aerodynamics angle of attack blade section aerodynamics characterization blades discontinuous Galerkin methodology flow simulation large eddy simulation panel method wind energy sector wind turbine airfoil wind turbines