CFD code comparison for 2D airfoil flows

Sørensen, Niels N.; Méndez, Beatriz; Muñoz, Arturo; Sieros, Giorgos; Jost, Eva; Lutz, Thorsten; Papadakis, G.; Voutsinas, Spyros G.; Barakos, George N.; Colonia, Simone; Baldacchino, Daniel; Baptista, C.; Ferreira, Célia

doi:10.1088/1742-6596/753/8/082019

Cited by 26 publications

(34 citation statements)

References 15 publications

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“…EllipSys3D was found to be 2-6 times faster while producing almost identical numerical results (Cavar et al, 2016). More recent sources also show that these two solvers yield comparable results (Sørensen et al, 2016;Yilmaz et al, 2017;Boorsma et al, 2018).…”

Section: Ellipsys3dmentioning

confidence: 79%

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Madsen¹,

Zahle²,

Sørensen³

et al. 2019

Wind Energ. Sci.

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Abstract. The wind energy industry relies heavily on computational fluid dynamics (CFD) to analyze new turbine designs. To utilize CFD earlier in the design process, where lower-fidelity methods such as blade element momentum (BEM) are more common, requires the development of new tools. Tools that utilize numerical optimization are particularly valuable because they reduce the reliance on design by trial and error. We present the first comprehensive 3-D CFD adjoint-based shape optimization of a modern 10 MW offshore wind turbine. The optimization problem is aligned with a case study from International Energy Agency (IEA) Wind Task 37, making it possible to compare our findings with the BEM results from this case study and therefore allowing us to determine the value of design optimization based on high-fidelity models. The comparison shows that the overall design trends suggested by the two models do agree, and that it is particularly valuable to consult the high-fidelity model in areas such as root and tip where BEM is inaccurate. In addition, we compare two different CFD solvers to quantify the effect of modeling compressibility and to estimate the accuracy of the chosen grid resolution and order of convergence of the solver. Meshes up to 14×106 cells are used in the optimization whereby flow details are resolved. The present work shows that it is now possible to successfully optimize modern wind turbines aerodynamically under normal operating conditions using Reynolds-averaged Navier–Stokes (RANS) models. The key benefit of a 3-D RANS approach is that it is possible to optimize the blade planform and cross-sectional shape simultaneously, thus tailoring the shape to the actual 3-D flow over the rotor. This work does not address evaluation of extreme loads used for structural sizing, where BEM-based methods have proven very accurate, and therefore will likely remain the method of choice.

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Section: Ellipsys3dmentioning

confidence: 79%

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Madsen¹,

Zahle²,

Sørensen³

et al. 2019

Wind Energ. Sci.

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show abstract

“…Figure 2 illustrates the computational setup with the current setting consisting of a DU airfoil. An O-mesh type was designed for the computations with a computational domain radius of 32 times the airfoil chord length R = 32c, which is in the order of the computational size recommended by Sørensen et al [27] for this type of simulations. The aim of the current study is to find the optimal MT position to increase DU91W(2)250 airfoil aerodynamic performance and to investigate its influence on the average power output of a 5 MW Wind turbine.…”

Section: Numerical Setupmentioning

confidence: 99%

Microtab Design and Implementation on a 5 MW Wind Turbine

et al. 2017

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Microtabs (MT) consist of a small tab placed on the airfoil surface close to the trailing edge and perpendicular to the surface. A study to find the optimal position to improve airfoil aerodynamic performance is presented. Therefore, a parametric study of a MT mounted on the pressure surface of an airfoil has been carried out. The aim of the current study is to find the optimal MT size and location to increase airfoil aerodynamic performance and to investigate its influence on the power output of a 5 MW wind turbine. Firstly, a computational study of a MT mounted on the pressure surface of the airfoil DU91W(2)250 has been carried out and the best case has been found according to the largest lift-to-drag ratio. This airfoil has been selected because it is typically used on wind turbine, such as the 5 MW reference wind turbine of the National Renewable Energy Laboratory (NREL). Second, Blade Element Momentum (BEM) based computations have been performed to investigate the effect of the MT on the wind turbine power output with different wind speed realizations. The results show that, due to the implementation of MTs, a considerable increase in the turbine average power is achieved.

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“…4 we note the unexpected, slight increase in error for EllipSys3D in the thrust value on the finest mesh level. It also surprising that the compressible solver seems to benefit so drastically from increase in cell count but recent studies (Sørensen et al, 2016) have suggested that it can be the case for some compressible solvers albeit perhaps not as much as shown here. Looking at the Prandtl-Glauert (Glauert, 1928) lift and drag correction:…”

Section: Mesh Convergence Study 10mentioning

confidence: 60%

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Madsen¹,

Zahle²,

Sørensen³

et al. 2018

Preprint

View full text Add to dashboard Cite

Abstract. The wind energy industry relies heavily on CFD to analyze new turbine designs. To utilize CFD further upstream the design process where lower fidelity methods such as BEM are more common, requires the development of new tools. Tools that utilize numerical optimization are particularly valuable because they reduce the reliance on design by trial and error. We present the first comprehensive 3D CFD adjoint-based shape optimization of a modern 10&thisp;MW offshore wind turbine. The optimization problem is aligned with a case study from IEA Wind Task 37, making it possible to compare our findings with the BEM results from this case study, allowing us to determine the value of design optimization based on high-fidelity models. The comparison shows, that the overall design trends suggested by the two models do agree, and that it is particularly valuable to consult the high-fidelity model in areas such as root and tip where BEM is inaccurate. In addition, we compare two different CFD solvers to quantify the effect of modeling compressibility and to estimate the accuracy of the chosen grid resolution and order of convergence of the solver. Meshes up to 14 · 106 cells are used in the optimization whereby flow details are resolved. The present work shows that it is now possible to successfully optimize modern wind turbines aerodynamically under normal operating conditions using RANS models. The key benefit of a 3D RANS approach is that it is possible to optimize the blade planform and cross-sectional shape simultaneously, thus tailoring the shape to the actual 3D flow over the rotor, which is particularly important near the root and tip of the blade. This work does not address evaluation of extreme loads used for structural sizing, where BEM-based methods have proven very accurate, and therefore will likely remain the method of choice.

show abstract

CFD code comparison for 2D airfoil flows

Cited by 26 publications

References 15 publications

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

Microtab Design and Implementation on a 5 MW Wind Turbine

Multipoint high-fidelity CFD-based aerodynamic shape optimization of a 10 MW wind turbine

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