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EPTT 2022
13th Spring School on Transition and Turbulence
Assessment of turbulence models for the simulation of the flow through a megawatt scale wind turbine rotor
Submission Author:
Marielle de Oliveira , SC
Co-Authors:
Marielle de Oliveira, Rodolfo Curci Puraca, Bruno Carmo
Presenter: Marielle de Oliveira
doi://10.26678/ABCM.EPTT2022.EPT22-0008
Abstract
The increase of the size of wind turbines to deliver power at megawatt scale, particularly for offshore application, brings a number of engineering challenges. The numerical modeling of these systems, considering the wind turbine geometry in full scale, is a valuable tool for design and performance analysis. To properly model the interaction between the turbine and the wind we need a proper turbulence model. This paper presents a comparison of two of the most recommended turbulence models, the Unsteady Reynolds Averaged Navier-Stokes (URANS) k-ω SST and the two-equation Detached Eddy Simulation (DES) applied in blade-resolved simulations of the NREL 5 MW reference wind turbine, in order to predict the rotor performance when it operates in optimal wind-power conversion efficiency, for a wind speed of 10 m/s at hub height. The power production, generated thrust, and forces distribution along the blade span were estimated. The computational analyses were carried out using a Computational Fluid Dynamics (CFD) methodology employing the Finite Volume Method (FVM) implemented in the OpenFOAM software. A numerical verification was conducted by comparing the CFD results against values obtained using the blade element momentum theory, implemented in OpenFAST. The performance of each turbulence model was assessed considering the computational cost and accuracy of the results. Both turbulence models presented satisfactory results when comparing with the results from OpenFAST, for the same environmental condition investigated. However the wake internal gradient present different patterns. For the DES turbulence model it was possible to observe with higher resolution the effects of the blade in the inner wake region. In addition, a different behavior of the flow that detaches along the blade span and transitions to the wake external pattern was also observed when comparing the turbulence models.
Keywords
Computational Fluid Dynamics - CFD, URANS, DES 2 Equations, NREL 5 MW Rotor, Blade-resolved Simulations, OpenFOAM
