Accurate load prediction by BEM with airfoil data from 3D RANS simulations

Schneider, Marc S.; Nitzsche, Jens; Hennings, Holger

doi:10.1088/1742-6596/753/8/082016

Cited by 12 publications

(17 citation statements)

References 6 publications

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“…Atmospheric turbulence, for example, is smeared out. The RAV‐AA method corresponds in its derivation regarding the annular averaging to the inverse‐BEM approach, which accounts for the rotor solidity (

σ = \frac{c B}{2 π r}

, c : chord length, B : number of blades) to perform the extension from the blade to the annular stream tube.…”

Section: Investigated Existing Methodsmentioning

confidence: 99%

Extracting the angle of attack on rotor blades from CFD simulations

et al. 2018

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In today's wind energy research, comparisons of low‐fidelity aerodynamic models with CFD simulations are common practice. While the approach for loads with respect to the rotor‐plane coordinate system such as distributed driving force or thrust is straightforward, a comparison of aerodynamic characteristics is more challenging. The radial distributions of lift, drag, and moment coefficient depend on the local angle of attack and inflow velocity, which cannot be directly determined from the flow field. It requires the elimination of the influence of the rotor blade's bound circulation and also involves the step from a three‐dimensional flow field to quantities, which depend on the blade radius. The present investigation analyzes 4 different approaches to determine the angle of attack and inflow velocity from three‐dimensional rotor simulations. In addition to 3 existing methods, a new line average technique is presented. It eliminates the effect of bound circulation by averaging along a closed shape, which is symmetric to the quarter‐chord point. All methods are assessed in cases with successively increasing complexity. The observed discrepancies are assigned to a different consideration of trailing and shed vortices. The line average approach was found to be a valuable alternative to existing approaches especially in unsteady cases and regarding the outer or tip sections of the rotor blade.

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σ = \frac{c B}{2 π r}

, c : chord length, B : number of blades) to perform the extension from the blade to the annular stream tube.…”

Section: Investigated Existing Methodsmentioning

confidence: 99%

Extracting the angle of attack on rotor blades from CFD simulations

et al. 2018

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“…CFD is increasingly used to re-investigate the modeled phenomena for large rotor scales. Efforts made by Rahimi et al [20,19,10,21] showed that the high fidelity of CFD simulations can help to improve the skewed wake engineering model for large rotor size turbines. Another example is the work of Yang et al [20] and Schneider et al [21] related to stall delay models.…”

Section: Introductionmentioning

confidence: 99%

“…Efforts made by Rahimi et al [20,19,10,21] showed that the high fidelity of CFD simulations can help to improve the skewed wake engineering model for large rotor size turbines. Another example is the work of Yang et al [20] and Schneider et al [21] related to stall delay models. Nevertheless, in all these works one of the major limitations for the improvement of these correction models using measurements or 3D CFD lies in the many uncertainties involved on the definition of AoA and underlying axial and tangential induced velocity for 3D flows.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of different methods for determining the angle of attack on wind turbine blades with CFD results under axial inflow conditions

et al. 2018

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This work presents an investigation on different methods for the calculation of the angle of attack and the underlying induced velocity on wind turbine blades using data obtained from three-dimensional Computational Fluid Dynamics (CFD). Several methods are examined and their advantages, as well as shortcomings, are presented. The investigations are performed for two 10MW reference wind turbines under axial inflow conditions, namely the turbines designed in the EU AVATAR and INNWIND.EU projects. The results show that the evaluated methods are in good agreement with each other at the mid-span, though some deviations are observed at the root and tip regions of the blades. This indicates that CFD results can be used for the calibration of induction modeling for Blade Element Momentum (BEM) tools. Moreover, using any of the proposed methods, it is possible to obtain airfoil characteristics for lift and drag coefficients as a function of the angle of attack. Nomenclature ρ Air density [kg m −3 ] Γ Circulation [m 2 s −1 ]

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“…The use of the 3D polar data is expected to be more beneficial for this purpose. Schneider et al [25] documented that the polar data extracted from the 3D CFD simulation of a 7.5 MW wind turbine enhanced the BEM prediction significantly. A similar conclusion was obtained very recently by Guma et al [26] for a 750 kW research turbine.…”

Section: Motivation and State Of The Artmentioning

confidence: 99%

Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

Bangga

2018

Fluids

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The present studies deliver the computational investigations of a 10 MW turbine with a diameter of 205.8 m developed within the framework of the AVATAR (Advanced Aerodynamic Tools for Large Rotors) project. The simulations were carried out using two methods with different fidelity levels, namely the computational fluid dynamics (CFD) and blade element and momentum (BEM) approaches. For this purpose, a new BEM code namely B-GO was developed employing several correction terms and three different polar and spatial interpolation options. Several flow conditions were considered in the simulations, ranging from the design condition to the off-design condition where massive flow separation takes place, challenging the validity of the BEM approach. An excellent agreement is obtained between the BEM computations and the 3D CFD results for all blade regions, even when massive flow separation occurs on the blade inboard area. The results demonstrate that the selection of the polar data can influence the accuracy of the BEM results significantly, where the 3D polar datasets extracted from the CFD simulations are considered the best. The BEM prediction depends on the interpolation order and the blade segment discretization.

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Accurate load prediction by BEM with airfoil data from 3D RANS simulations

Cited by 12 publications

References 6 publications

Extracting the angle of attack on rotor blades from CFD simulations

Extracting the angle of attack on rotor blades from CFD simulations

Evaluation of different methods for determining the angle of attack on wind turbine blades with CFD results under axial inflow conditions

Comparison of Blade Element Method and CFD Simulations of a 10 MW Wind Turbine

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