Actuator line simulation of a tidal turbine in straight and yawed flows

Baratchi, F.; Jeans, Tiger L.; Gerber, A. G.

doi:10.1016/j.ijome.2017.08.003

Cited by 19 publications

(8 citation statements)

References 24 publications

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“…Vortices shedding from blade tips persist in a certain distance and then merge into a vorticity sheet in the downstream. This is consistent with previous research [34]. However, the underestimation of vorticity using the AL method can also be seen, since there is no explicit suction side and pressure side of a blade as that in the FRG method.…”

Section: Discussionsupporting

confidence: 92%

“…However, some discrepancies occurred due to failure in the simulation of the turbulence generated in the boundary layer and from the blade vibration. Baratchi et al [34] also used the AL method coupled with LES to simulate a TST in straight and yawed flows. Their results showed that the AL method was capable of capturing wake unsteadiness and tip and root vortices in the wake.…”

Section: Introductionmentioning

confidence: 99%

“…Their results showed that the AL method was capable of capturing wake unsteadiness and tip and root vortices in the wake. The advantage of the AL method over the BEM method was also highlighted in [34]. Compared with the FRG method, Bachant [35] found that the AL method could provide four orders of magnitude reduction in computational expense when using the Reynolds-averaged Navier-Stokes (RANS) with turbulence model.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Actuator Line Method and Full Rotor Geometry Simulations of the Wake Field of a Tidal Stream Turbine

Lin

Zhang

et al. 2019

Water

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This study aims to investigate the wake characteristics of a horizontal axis tidal stream turbine supported by a monopile using a numerical approach. Computational fluid dynamics (CFD) simulations based on the open source software OpenFOAM have been performed to enhance understanding of a turbine’s wake. The numerical simulations adopt both the actuator line method and the full rotor geometry method. The numerical results are found to be consistent with experimental data, although some discrepancies are observed at a distance of one rotor diameter downstream. Comparison of numerical results from both methods is performed. The results show that both methods can obtain important flow features and provide similar simulation in the wake of the turbine model. The actuator line method is able to give a better prediction in stream-wise velocity distribution, although it underestimates the turbulence intensity, circumferential velocity and vorticity magnitude slightly, compared with the full rotor geometry method. It is also found that the wake of the monopile and the rotor interact strongly in the downstream field, especially in the region immediately behind the structure. A strong interaction occurs within approximately two rotor diameters downstream.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of Actuator Line Method and Full Rotor Geometry Simulations of the Wake Field of a Tidal Stream Turbine

Lin

Zhang

et al. 2019

Water

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“…The actuator line (AL) method includes the effects of non-uniform loading and extends BEM to distribute loads along rotating lines which represent blades, rather than average them over an area [12], [32], [33].…”

Section: ) Actuator Line Modelmentioning

confidence: 99%

Review of tidal turbine wake modelling methods

Jump

Macleod

Wills³

2020

Int. J. Mar. Ene.

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Enabling Future Arrays in Tidal (EnFAIT) is an EU Horizon 2020 flagship tidal energy project. It aims to demonstrate the development, operation and decommissioning of the world’s largest tidal array (six turbines), over a five-year period, to prove a cost reduction pathway for tidal energy and confirm that it can be cost competitive with other forms of renewable energy. To determine the optimal site layout and spacing between turbines within a tidal array, it is essential to accurately characterise tidal turbine wakes and their effects. This paper presents a state-of-the-art review of tidal turbine wake modelling methods, with an overview of the relevant fundamental theories. Numerical and physical modelling research completed by both academia and industry are considered to provide an overview of the contemporary understanding in this area. The scalability of single device modelling techniques to an array situation is discussed, particularly with respect to wake interactions.

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“…For example, Harrison [98] reports inconsistencies between the actuator BEM and actuator disk's predictions of power of in-line turbines, using an array of 10 turbines with infinite transverse rows: 7D and 2D, downstream and lateral offset, respectively. In comparison, results using the actuator line have been promising, although at a high cost, for predicting power and flow properties in a turbine array [82], [93], [94].…”

Section: Numerical Simulation Of Turbine Performance and Wake Amentioning

confidence: 99%

A Review on Numerical Development of Tidal Stream Turbine Performance and Wake Prediction

et al. 2020

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Recently, the output of Computational Fluid Dynamic (CFD) prediction on tidal stream turbine systems has been receiving great attention owing to the vast and untapped tidal stream potential. For several years, many publications have documented the accuracy of CFD methods for steady flows, but not for unsteady flows. A challenging area persisting in the computational field is its dependence on large computing resources, and the unsteady nature of usual tidal streams. To overcome this problem, researchers have proposed modelling simpler, representative devices or combined CFD with alternative predictive methods. Nevertheless, the turbulent modelling has been a critical issue in the CFD methods and great effort has been devoted to the study of turbulence and wave effect on the wake and functioning of the turbine. The present paper is a review of CFD application on tidal stream turbine performance in both steady and unsteady flows. The performance of the turbine predicted by actuator and blade resolved methods, has been in accordance with laboratory observations. Findings of the wake have been both consistent and inconsistent with measurements, arising from interpretation of the blade force, fluid-solving method and onset flow model, and downstream range distance. With regards to arrays, preliminary work shows turbine arrangement can have profound effects in the onset flow, and in consequence, the performance of adjacent turbine rows. The results reported appear to support the wind similarity assumption, such as wake Gaussian velocity distributions and fluctuating turbine output in unsteady flows. Under the influence of surface waves, the wake recovers faster than steady flow condition due to the flow's convective acceleration, but the mean performance stays almost equal. The findings in this paper give a critical review and insight of important implications for future turbine research, such as experimental validation of the turbine prediction output in small and large arrays. INDEX TERMS Computational fluid dynamic, tidal stream turbine, unsteady flow, turbine performance, wake characteristics.

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Actuator line simulation of a tidal turbine in straight and yawed flows

Cited by 19 publications

References 24 publications

Comparison of Actuator Line Method and Full Rotor Geometry Simulations of the Wake Field of a Tidal Stream Turbine

Comparison of Actuator Line Method and Full Rotor Geometry Simulations of the Wake Field of a Tidal Stream Turbine

Review of tidal turbine wake modelling methods

A Review on Numerical Development of Tidal Stream Turbine Performance and Wake Prediction

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