A computationally efficient engineering aerodynamic model for swept wind turbine blades

Li, Ang; Pirrung, Georg Raimund; Gaunaa, Mac; Madsen, Helge Aagaard; Horcas, Sergio González

doi:10.5194/wes-2021-96

Cited by 6 publications

(4 citation statements)

References 20 publications

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“…A similar pattern of spanwise load redistribution was also observed for swept blades in the previous works (Li et al, 2018(Li et al, , 2020(Li et al, , 2021. However, the redistribution of the loads only takes place where the blade is swept.…”

Section: Dihedral Blade With Zero Conesupporting

confidence: 82%

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A computationally efficient engineering aerodynamic model for non-planar wind turbine rotors

Gaunaa

Pirrung

et al. 2021

Preprint

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Abstract. In the present work, a computationally efficient engineering model for the aerodynamic load calculation of non-planar wind turbine rotors is proposed. The method is based on the vortex cylinder model, and can be used in two ways: either as a correction to the currently widely used blade element momentum (BEM) method, or used as the main model, replacing the BEM method in the engineering modelling complex. The proposed method needs the same order of computational effort as the ordinary BEM method, which makes it ideal for time-domain aero-servo-elastic simulations. The results from the proposed method are compared with results from two higher-fidelity aerodynamic models: a lifting-line method and a Navier-Stokes solver. For planar rotors, the aerodynamic loads are identical to the current BEM model when the drag force is excluded during the calculation of the induced velocities. For non-planar rotors, the influence of the blade out-of-plane shape, measured by the difference of the load between the non-planar rotor and the planar rotor, is in very good agreement with higher-fidelity models. Meanwhile, the existing BEM methods, even with a correction of radial induction included, show relatively large deviations from the higher-fidelity method results.

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Section: Dihedral Blade With Zero Conesupporting

confidence: 82%

“…In the present work, only the out-of-plane shape of the blade is considered, which means the blade is assumed to have no in-plane sweep. The engineering aerodynamic model for the blades with only in-plane shapes is described by Li et al (2021). The structure of the work is as follows: the Kutta-Joukowski analysis of the non-planar rotor is performed in Sect.…”

mentioning

confidence: 99%

A computationally efficient engineering aerodynamic model for non-planar wind turbine rotors

Gaunaa

Pirrung

et al. 2021

Preprint

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“…There are, however, situations that involve the induced velocities throughout the rotor plane rather than just along straight LLs. An example is a swept rotor, with the LL curved in the plane of rotation, which has been the subject of a significant amount of recent research, e.g., Fritz et al (2022), Li et al (2022b), and Gemaque et al (2022). The first two studied swept wind turbine blades using different approximations for the induced velocities.…”

Section: Woodmentioning

confidence: 99%

“…The first two studied swept wind turbine blades using different approximations for the induced velocities. Fritz et al (2022) used a restricted version of the analysis developed here, whereas Li et al (2022b) used a vortex-cylinder model of the wake. It is suggested that the present analysis is simpler and more general.…”

Section: Woodmentioning

confidence: 99%

Calculation of the velocities induced by the trailing vorticity in the rotor plane of a horizontal-axis turbine or propeller

Wood

2024

Front. Energy Res.

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Lifting line (LL) analysis of propellers and horizontal-axis turbines requires the axial and circumferential velocities induced by the vortex system representing the blades and the trailing vorticity. If the blades are straight and radial, the induced velocities along the LLs are due only to the trailing vorticity. Accurate two-term approximations for these velocities have been developed from the exact Kawada–Hardin (KH) equations for the velocity field of a doubly infinite helical vortex of constant pitch and radius, Wood et al. (Ocean Engineering, 2021, 235). This paper describes a straightforward extension of the approximations to give the induced velocities anywhere in the equivalent of the rotor plane for a doubly infinite helix. The third term in the approximation of the KH equations is derived and compared to an alternative third term due to Okulov (Journal of Fluid Mechanics, 2004, 521, 319–342). Both three-term approximations produce a small improvement in accuracy over the two-term approximations for a range of operating conditions for turbines and propellers. Okulov’s third term is superior. To determine the induced velocities for a singly infinite trailing vortex behind a rotor, an additional equation is derived from the Biot–Savart law. Numerical examples show that the resulting equations provide accurate estimates for the induced velocities over the rotor plane. The main application of the analysis is to account for blade sweep and coning by including the angle between the vortex origin and the control point at which the velocities are required, often the center of each blade element.

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An efficient blade sweep correction model for blade element momentum theory

2022

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This article proposes an efficient correction model that enables the extension of the blade element momentum method (BEM) for swept blades. Standard BEM algorithms, assuming a straight blade in the rotor plane, cannot account for the changes in the induction system introduced by blade sweep. The proposed extension corrects the axial induction regarding two aspects: the azimuthal displacement of the trailed vorticity system and the induction of the curved bound vortex on itself. The extended algorithm requires little additional processing work and maintains BEM's streamtube independent approach. The proposed correction model is applied to simulations of swept blade geometries based on the IEA 15 MW reference wind turbine. Results show good agreement with lifting line simulations that inherently can account for the swept blade geometry. Blade sweep couples bending and torsion deformations by curving the blade axis in the inplane direction. As such, it can be used to passively alleviate loads and, thus, aeroelastically tailor wind turbine blades. The implementation of aeroelastic tailoring techniques, and the aeroelastic analysis in general, becomes increasingly significant with the size of wind turbine rotors continually rising. Due to its low computing complexity, BEM remains a crucial tool in the aerodynamic and aeroelastic analysis of wind turbine rotors. Thus, the proposed correction model contributes to a fast and accurate evaluation of swept blade designs.

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A computationally efficient engineering aerodynamic model for swept wind turbine blades

Cited by 6 publications

References 20 publications

A computationally efficient engineering aerodynamic model for non-planar wind turbine rotors

A computationally efficient engineering aerodynamic model for non-planar wind turbine rotors

Calculation of the velocities induced by the trailing vorticity in the rotor plane of a horizontal-axis turbine or propeller

An efficient blade sweep correction model for blade element momentum theory

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