Development and Validation of Generalized Lifting Line Based Code for Wind Turbine Aerodynamics

Schepers, J.G.; Garrel, A. van; Grasso, Francesco

doi:10.2514/6.2011-146

Cited by 21 publications

(7 citation statements)

References 2 publications

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“…Equation (11) gives an expression for the evaluation of the induction of an infinite helical vortex filament. The tip vortex of a wind turbine blade, however, only spans downstream of the rotor and, thus, resembles a semi-infinite helical vortex filament.…”

Section: Velocity Induced By a Semi-infinite Helical Vortex Filamentmentioning

confidence: 99%

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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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Section: Velocity Induced By a Semi-infinite Helical Vortex Filamentmentioning

confidence: 99%

“…Their study showed that backward sweep can be used to reduce flapwise fatigue and extreme loads. Using the lifting line code AWSM coupled to a structural solver, Grasso et al 11 show that an aft swept blade oscillates less than a straight reference blade when hit by a gust, indicating the potential for a reduction of fatigue loading.…”

Section: Introductionmentioning

confidence: 99%

An efficient blade sweep correction model for blade element momentum theory

2022

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“…Typical implementation of such code can be found in [20]. The validation of this code performed in [13] compared well with theoretical results and with similar vortex codes [21,22]. The approach chosen was to establish a database of tip-loss factors as function of a given set of parameters.…”

Section: Approach Using Vortex Methodsmentioning

confidence: 99%

Vortex methods to answer the need for improved understanding and modelling of tip‐loss factors

Branlard¹,

Dixon

Gaunaa³

2013

IET Renewable Power Generation

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Standard blade element momentum (BEM) codes use Prandtl's tip-loss correction which relies on simplified vortex theory under the assumption of optimal operating condition and no wake expansion. The various tip-loss functions found in the literature are listed. A simple comparison between them shows important differences in Annual Energy Production which reveal a large uncertainty in current BEM-based computations. A new tip-loss correction for implementation in BEM codes has been developed using a lifting-line code to account for the effect of wake expansion, roll-up and distortion under many operating conditions. A database of tip-loss corrections is established for further use in BEM codes. This model is closer to the physics of the flow and hence, a better assessment of the performance of wind turbines by this method is expected.

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“…Afjeh and Keith 10 also state that at adequately high enough airspeeds, the wake deformation effects are negligible since the airspeed convects the tip-vortex away thereby removing it further away from the adjacent blade thereby minimizing the blade interaction effects that are inherently ignored in the LL theory. Grasso et al 11 , have successfully applied the LL theory to wind turbines with swept back wings and winglets and under yawed condition and validated against experimental data. Fould and Fiddles 12 observed that the LL theory resulted in a slight underprediction of the overall power as compared to experiments and reasoned that they are due to the strong 3-D effects such as radial flow and boundary layer separation along the blade, which is ignored in the LL theory.…”

Section: Table 1: Comparison Of Physics and Capabilities Of Bem And Lmentioning

confidence: 98%

Validation and Assesment of Lower Order Aerodynamics Based Design of Ram Air Turbines

Renganathan¹,

Denney²,

Duquerrois³

et al. 2014

12th International Energy Conversion Engineering Conference

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Ram Air Turbines (RATs) are small-scale wind powered turbines installed in commercial and military aircraft to generate power for in-flight hydraulics and electronics, in the event of total power failure. There is a need for efficient design of RATs that maximizes the power by minimizing weight and cost. The Lifting Line (LL) theory is applied towards the aerodynamic analysis of a 2-bladed RAT and the approach is validated against experimental data. The goal of this paper is to demonstrate the feasibility of the LL theory as an efficient tool for conceptual design of RATs. First, the methodology is validated by reproducing an existing RAT blade design for a known operating condition. Next, off-design conditions are explored for a design point. The validation study demonstrated that the LL theory can predict aerodynamic performance of RATs within 20% up to the transonic regime. Given the simple computational implementation, cheap computational cost and observed level of accuracy the LL theory appears to be an attractive approach towards the conceptual design and design space exploration of RATs. Thus, the paper also investigates the aerodynamic design capabilities of the LL theory, given some constraints and operating condition.

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Development and Validation of Generalized Lifting Line Based Code for Wind Turbine Aerodynamics

Cited by 21 publications

References 2 publications

An efficient blade sweep correction model for blade element momentum theory

An efficient blade sweep correction model for blade element momentum theory

Vortex methods to answer the need for improved understanding and modelling of tip‐loss factors

Validation and Assesment of Lower Order Aerodynamics Based Design of Ram Air Turbines

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