Vortex simulations of wind turbines operating in atmospheric conditions using a prescribed velocity‐vorticity boundary layer model

Ramos‐García, Néstor; Spietz, Henrik Juul; Sørensen, Jens Nørkær; Walther, Jens Honoré

doi:10.1002/we.2225

Cited by 19 publications

(31 citation statements)

References 31 publications

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“…The Navier-Stokes equations are solved using the SIMPLE algorithm (Patankar and Spalding, 1972), and the convective terms are discretized using a QUICK scheme (Leonard, 1979). The wind turbine rotors are represented by actuator discs (ADs) based on airfoil data as presented in Réthoré et al (2014). The RANS-AD model can only model stiff blades.…”

Section: Ellipsys3d Rans-admentioning

confidence: 99%

“…In order to do so, a simplification of the 4R-V29 wind turbine is used so that a fair comparison with a equivalent single-rotor wind turbine can be made. The simplified 4R-V29 wind turbine has a zero toe-out angle, and the force distributions are defined by prescribed normalized blade force distributions (calculated by Réthoré et al, 2014, employing a detached eddy simulation of the NREL-5MW rotor for a wind speed of 8 m s −1 ). The blade force distributions are scaled by the hub height velocity U H , R, C T , C P and the rotational speed (RPM) as discussed by van der Laan et al (2015).…”

Section: Wake Recovery Of the 4r-v29 Wind Turbinementioning

confidence: 99%

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Power curve and wake analyses of the Vestas multi-rotor demonstrator

et al. 2019

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Abstract. Numerical simulations of the Vestas multi-rotor demonstrator (4R-V29) are compared with field measurements of power performance and remote sensing measurements of the wake deficit from a short-range WindScanner lidar system. The simulations predict a gain of 0 %–2 % in power due to the rotor interaction at below rated wind speeds. The power curve measurements also show that the rotor interaction increases the power performance below the rated wind speed by 1.8 %, which can result in a 1.5 % increase in the annual energy production. The wake measurements and numerical simulations show four distinct wake deficits in the near wake, which merge into a single-wake structure further downstream. Numerical simulations also show that the wake recovery distance of a simplified 4R-V29 wind turbine is 1.03–1.44 Deq shorter than for an equivalent single-rotor wind turbine with a rotor diameter Deq. In addition, the numerical simulations show that the added wake turbulence of the simplified 4R-V29 wind turbine is lower in the far wake compared with the equivalent single-rotor wind turbine. The faster wake recovery and lower far-wake turbulence of such a multi-rotor wind turbine has the potential to reduce the wind turbine spacing within a wind farm while providing the same production output.

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Section: Ellipsys3d Rans-admentioning

confidence: 99%

Section: Wake Recovery Of the 4r-v29 Wind Turbinementioning

confidence: 99%

Power curve and wake analyses of the Vestas multi-rotor demonstrator

et al. 2019

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“…The in‐house vortex code MIRAS, 17‐19,26 that is, Method for Interactive Rotor Aerodynamic Simulations, has been used in the current work. MIRAS is a multi‐fidelity aerodynamic tool for wind turbine performance analyses.…”

Section: Methodsmentioning

confidence: 99%

“…The VIPM being the most physically correct approach, since it resolves the actual geometry of the blade and accounts for the viscous effects enclosed inside the boundary layer. Regarding the flow/wake models implemented in MIRAS, they range from the classic free‐wake using filaments, 17 the hybrid filament‐mesh 18 which keeps the filament structure of the wake, to the hybrid filament‐particle‐mesh 19 . The hybrid filament‐particle‐mesh being regarded as the highest order since it resolves the vorticity equation, which is obtained by taking the curl of the Navier‐Stokes equation, and describes the evolution of the vorticity of a fluid particle as it moves with the flow.…”

Section: Introductionmentioning

confidence: 99%

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Aero‐hydro‐servo‐elastic coupling of a multi‐body finite‐element solver and a multi‐fidelity vortex method

2020

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The manuscript presents a novel aero‐hydro‐servo‐elastic coupling framework, MIRAS‐HAWC2. In this coupling, the wind turbine blades and rotor‐wake aerodynamics are modeled using a modified lifting‐line theory which accounts for blade curvature, combined with a hybrid vortex method. The wind turbine structure and foundation are modeled using a finite‐element and multi‐body system approach. Last, hydrodynamics are modeled using Airy wave theory together with Morison's equation. An initial assessment of the performance of the aeroelastic coupling framework has been performed for steady rotor‐only cases, assuming laminar inflow without shear. This included a comparison against fully resolved computational fluid dynamics, for both stiff and flexible blades showing an excellent agreement. In a second stage, the aero‐hydro‐servo‐elastic coupling is used, comparing MIRAS‐HAWC2 as well as blade‐element momentum‐based simulations with selected results from the Offshore Code Comparison Collaboration projects (OC3 and OC4), which study the NREL 5 MW turbine mounted on different offshore support structures. A good agreement has been obtained for the simulations of a monopile with rigid foundation, a tripod, and jacket support structures.

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Investigation of the floating IEA Wind 15 MW RWT using vortex methods Part I: Flow regimes and wake recovery

et al. 2021

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Floating wind turbines have the potential to enable global exploitation of offshore wind energy, but there is a need to further understand the complex aerodynamic phenomena they can encounter due to floater induced rotor motion. Aerodynamic models traditionally used in the wind energy sector, like the Blade Element Momentum (BEM) theory, may not be capable of capturing the dynamic phenomena that occur when the rotor moves in and out of its own wake. In the present paper, we therefore compare an industry standard BEM‐based code to a state of the art vortex solver, to investigate the phenomena in detail and further clarify the capabilities and limitations of both methods. An initial benchmark of the two codes using the IEA Wind 15 MW RWT mounted on the WindCrete spar‐buoy floater is carried out. Three different scenarios are taken into account: a bottom‐fixed, a floating case, and a floating case subject to regular waves. Growing discrepancies between the codes have been observed with the increasing complexity of the simulations. Moreover, large differences between the wake generated by a bottom fixed and a floating turbine have been observed, with the latter one experiencing a faster recovery. To further explore the floating turbines behaviors that can affect the rotor performance and wake, a systematic investigation of the mean tilt angle influence in the wake development has been carried out. Further, to account for the oscillatory motion of a floating turbine, a parametric study where the floater motion is prescribed in both pitch and surge degrees of freedom (DoF) is designed. The study covers a large variety of scenarios; a wide range of relevant frequencies and amplitudes are taken into account in under and above‐rated wind conditions. A total of more than 28 unique cases have been defined and simulated with both fidelity models. The results include the downstream evolution of the wake recovery and intensity of the turbulent disturbances induced by the rotor. The generic nature of the study allows to characterize the flow and performance effects and enables subsequent generalization to floater designs of given natural frequency and motion amplitude. It has been found that the BEM and LL predictions of the maximum loading in the blade root and tower bottom compare quite well, except for the case of large oscillation frequency in above rated conditions, where the BEM method under‐predicts the loads. Moreover, the use of a vortex solver makes it possible to look in depth into the wake characteristics, in which large differences are observed between the bottom‐fixed and the floating case in non‐turbulent inflow conditions. It has been found that the frequency and amplitude of the turbine oscillations can have a strong impact on the recovery of the wake. Moreover, we have found a link between short time intervals of large FA blade tip displacements and a faster break down of the wake. Finally it has been shown that a floating wind turbine with large and fast oscillations can transition between the differ...

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Vortex simulations of wind turbines operating in atmospheric conditions using a prescribed velocity‐vorticity boundary layer model

Cited by 19 publications

References 31 publications

Power curve and wake analyses of the Vestas multi-rotor demonstrator

Power curve and wake analyses of the Vestas multi-rotor demonstrator

Aero‐hydro‐servo‐elastic coupling of a multi‐body finite‐element solver and a multi‐fidelity vortex method

Investigation of the floating IEA Wind 15 MW RWT using vortex methods Part I: Flow regimes and wake recovery

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