Study on Actuator Line Modeling of Two NREL 5-MW Wind Turbine Wakes

Yu, Ziying; Zheng, Xing; Ma, Qingwei

doi:10.3390/app8030434

Cited by 33 publications

(18 citation statements)

References 25 publications

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“…It is to be noted that there is no tip-loss correction in the ALM-LBM-LES model. Yu et al [35] showed that adding a tip-loss correction when modeling a horizontal axis wind turbine can reduce the error of the predicted power. It could be an interesting addition to the ALM-LBM-LES model.…”

Section: Discussionmentioning

confidence: 99%

Wake of a Ducted Vertical Axis Tidal Turbine in Turbulent Flows, LBM Actuator-Line Approach

et al. 2019

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Vertical axis tidal turbines are devices that extract the kinetic energy from tidal currents. Tidal currents can be highly turbulent. Since ambient turbulence affects the turbine hydrodynamic, it is critical to understand its influence in order to optimize tidal farms. Actuator Line Model (ALM) combined with Large Eddy Simulation (LES) is a promising way to comprehend this phenomenon. In this article, an ALM was implemented into a Lattice Boltzmann Method (LBM) LES solver. This implementation gives good results for predicting the wake of a vertical axis tidal turbine placed into a turbulent boundary layer. The validated numerical configuration was then used to compute the wake of a real size ducted vertical axis tidal turbine. Several upstream turbulence rates were simulated. It was found that the shape of the wake is strongly influenced by the ambient turbulence. The cost-to-precision ratio of ALM-LBM-LES compared to fully resolved LBM-LES makes it a promising way of modeling tidal farms.

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Section: Discussionmentioning

confidence: 99%

Wake of a Ducted Vertical Axis Tidal Turbine in Turbulent Flows, LBM Actuator-Line Approach

et al. 2019

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“…The simulation physical domains used in this paper are the same as Yu et al [28]. Their three-dimensional sketches are shown in Figures 6 and 7.…”

Section: Computational Wind Turbine Modelmentioning

confidence: 99%

“…To be exact, the shaft tilt angle is considered in the structural part, which will make the external force of blade increased because of the gravity component. The simulation physical domains used in this paper are the same as Yu et al [28]. Their three-dimensional sketches are shown in Figures 6 and 7.…”

Section: Computational Wind Turbine Modelmentioning

confidence: 99%

“…In addition, the wind turbine blade deflection solver is added in ALM, named EALM. Compared to the work of Yu et al [28], the parameter settings are all the same expect that the LES (Large Eddy Simulation) model is used instead of RANS (Reynolds Average Navier-Stokes). That is because the LES model will get more accurate results about the vorticities than RANS and the influence of the wake flows to elastic blade is studied in this research.…”

Section: Computational Wind Turbine Modelmentioning

confidence: 99%

“…To analyze the influence of elastic blade in the wake flows, an array of two NREL 5 MW wind turbines is studied (see Figure 7) with EALM. The results are extracted after the upstream wind turbine rotating 40 revolutions, and the corresponding simulation time is around 260 s. According to research [28], the rotor speed of downstream wind turbine is set as 8.11 rpm to maximize its output power.…”

Section: Wake Flows Analysismentioning

confidence: 99%

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Aeroelastic Performance Analysis of Wind Turbine in the Wake with a New Elastic Actuator Line Model

Zheng

et al. 2020

Water

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The scale of a wind turbine is getting larger with the development of wind energy recently. Therefore, the effect of the wind turbine blades deformation on its performances and lifespan has become obvious. In order to solve this research rapidly, a new elastic actuator line model (EALM) is proposed in this study, which is based on turbinesFoam in OpenFOAM (Open Source Field Operation and Manipulation, a free, open source computational fluid dynamics (CFD) software package released by the OpenFOAM Foundation, which was incorporated as a company limited by guarantee in England and Wales). The model combines the actuator line model (ALM) and a beam solver, which is used in the wind turbine blade design. The aeroelastic performances of the NREL (National Renewable Energy Laboratory) 5 MW wind turbine like power, thrust, and blade tip displacement are investigated. These results are compared with some research to prove the new model. Additionally, the influence caused by blade deflections on the aerodynamic performance is discussed. It is demonstrated that the tower shadow effect becomes more obvious and causes the power and thrust to get a bit lower and unsteady. Finally, this variety is analyzed in the wake of upstream wind turbine and it is found that the influence on the performance and wake flow field of downstream wind turbine becomes more serious.

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A new tip correction for actuator line computations

Dag

Sørensen

2019

Wind Energy

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The actuator line method (ALM) is today widely used to represent wind turbine loadings in computational fluid dynamics (CFD). As opposed to resolving the whole blade geometry, the methodology does not require geometry-fitted meshes, which makes it fast to apply. In ALM, tabulated airfoil data are used to determine the local blade loadings, which subsequently are projected to the CFD grid using a Gaussian smearing function. To achieve accurate blade loadings at the tip regions of the blades, the width of the projection function needs to be narrower than the local chord lengths, requiring CFD grids that are much finer than what is actually needed in order to resolve the energy containing turbulent structures of the atmospheric boundary layer (ABL). On the other hand, employing large widths of the projection function may result in too large tip loadings. Therefore, the number of grid points required to resolve the blade and the width of the projection function have to be restricted to certain minimum values if unphysical corrections are to be avoided. In this paper, we investigate the cause of the overestimated tip loadings when using coarse CFD grids and, based on this, introduce a simple and physical consistent correction technique to rectify the problem. To validate the new correction, it is first applied on a planar wing where results are compared with the lifting-line technique. Next, the NREL 5-MW and Phase VI turbines are employed to test the correction on rotors. Here, the resulting blade loadings are compared with results from the blade-element momentum (BEM) method. In both cases, it is found that the new correction greatly improves the results for both normal and tangential loads and that it is possible to obtain accurate results even when using a very coarse blade resolution. KEYWORDSactuator line, LES of wind turbines, tip correction, wind turbine blade loadings INTRODUCTIONThe actuator line method (ALM) was developed as a numerical technique to facilitate the representation of the rotor blades in computational fluid dynamics (CFD) simulations of wind turbines. 1 The ALM is based on a blade-element approach in which body forces are introduced in the Navier-Stokes equations along lines representing the blades of the wind turbine. It was originally developed for simulating the wake behind a single horizontal axis wind turbine, 1-4 and has later been extended to simulate flows in wind farms, 5-12 and applied to vertical axis wind turbines, 13,14 tidal turbines, 15-17 and helicopters. 18 For a review of the ALM and related methods, the reader is referred to Breton et al. 19 In the ALM, the body forces are obtained from tabulated airfoil data employing the local angle of attack along the blades as input. The local angle of attack is defined from the local relative velocity, which is determined at each time step while running a simulation. After having determined the local forces, they are projected from the lines representing the rotor blades to the CFD grid points. A main issue of the technique is that it ...

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Study on Actuator Line Modeling of Two NREL 5-MW Wind Turbine Wakes

Cited by 33 publications

References 25 publications

Wake of a Ducted Vertical Axis Tidal Turbine in Turbulent Flows, LBM Actuator-Line Approach

Wake of a Ducted Vertical Axis Tidal Turbine in Turbulent Flows, LBM Actuator-Line Approach

Aeroelastic Performance Analysis of Wind Turbine in the Wake with a New Elastic Actuator Line Model

A new tip correction for actuator line computations

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