In-phase and out-of-phase pitch and roll oscillations of model wind turbines within uniform arrays

Fu, Sizu; Zhang, Buen; Zheng, Yuan; Chamorro, Leonardo P.

doi:10.1016/j.apenergy.2020.114921

Cited by 14 publications

(4 citation statements)

References 32 publications

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“…In the literature, distortion of near wake structures by the surge and pitch motions of the platform was observed in computational results obtained using the free vortex method (Farrugia, Sant & Micallef 2016;Lee & Lee 2019) and the unsteady Reynolds-averaged Navier-Stokes (URANS) method in recent studies (Liu et al 2016;Tran & Kim 2016). Such influence of platform pitch and surge motions on the wake was also analysed in several wind tunnel experiments, and different effects were observed (Rockel et al 2014(Rockel et al , 2017Fu et al 2019Fu et al , 2020Schliffke, Aubrun & Conan 2020;Feist, Sotiropoulos & Guala 2021). For instance, Rockel et al (2014Rockel et al ( , 2017 considered the effects of platform pitch motion on the far wake evolution and observed a decrease of wake replenishing due to a time-averaged upward wake deflection.…”

Section: Introductionmentioning

confidence: 99%

Onset of wake meandering for a floating offshore wind turbine under side-to-side motion

Dong

Yang

2022

J. Fluid Mech.

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Wind turbine wakes, being convectively unstable, may behave as an amplifier of upstream perturbations and make downstream turbines experience strong inflow fluctuations. In this work, we investigate the effects of the side-to-side motion of a floating offshore wind turbine (FOWT) on wake dynamics using large-eddy simulation and linear stability analysis (LSA). When the inflow turbulence intensity is low, simulation results reveal that the turbine motion with certain Strouhal numbers $St = fD/U_\infty \in (0.2,0.6)$ (where $f$ is the motion frequency, $D$ is the rotor diameter, and $U_\infty$ is the incoming wind speed), which overlap with the Strouhal numbers of wake meandering induced by the shear layer instability, can lead to wake meandering with amplitudes being one order of magnitude larger than the FOWT motion for the most unstable frequency. For high inflow turbulence intensity, on the other hand, the onset of wake meandering is dominated by the inflow turbulence. The probability density function of the spanwise instantaneous wake centres is observed being non-Gaussian and closely related to that of the side-to-side motion. This complements the existing wake meandering mechanisms, that the side-to-side motion of an FOWT can be a novel origin for the onset of wake meandering. It is also found that LSA can predict the least stable frequencies and the amplification factor with acceptable accuracy for motion amplitude $0.01D$ . Effects of nonlinearity are observed when motion amplitude increases to $0.04D$ , for which the most unstable turbine oscillations shift slightly to lower frequencies and the amplification factor decreases.

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Section: Introductionmentioning

confidence: 99%

Onset of wake meandering for a floating offshore wind turbine under side-to-side motion

Dong

Yang

2022

J. Fluid Mech.

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“…The method suggested to achieve this is individual rotor yaw since it is a well‐established technique; however, the effects of rotor tilt are also of interest 51,52 and could be examined in further works. The effects of pitch and roll in floating turbines may also be applied to the multirotor case, as has been investigated in single rotor wind tunnel studies (for example, 53‐56 ) and numerical studies of Xiao and Yang 57 . More than this, the impacts of different atmospheric boundary layers 58‐60 and wave structures 61 on turbine wakes may also be extended to multirotor studies.…”

Section: Introductionmentioning

confidence: 99%

Wake steering of multirotor wind turbines

et al. 2021

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In this paper, wake steering is applied to multirotor turbines to determine whether it has the potential to reduce wind plant wake losses. Through application of rotor yaw to multirotor turbines, a new degree of freedom is introduced to wind farm control such that wakes can be expanded, channelled or redirected to improve inflow conditions for downstream turbines. Five different yaw configurations are investigated (including a baseline case) by employing large‐eddy simulations (LES) to generate a detailed representation of the velocity field downwind of a multirotor wind turbine. Two lower‐fidelity models from single‐rotor yaw studies (curled‐wake model and analytical Gaussian wake model) are extended to the multirotor case, and their results are compared with the LES data. For each model, the wake is analysed primarily by examining wake cross‐sections at different downwind distances. Further quantitative analysis is carried out through characterisations of wake centroids and widths over a range of streamwise locations and through a brief analysis of power production. Most significantly, it is shown that rotor yaw can have a considerable impact on both the distribution and magnitude of the wake velocity deficit, leading to power gains for downstream turbines. The lower‐fidelity models show small deviation from the LES results for specific configurations; however, both are able to reasonably capture the wake trends over a large streamwise range.

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“…It was found that the values were between the engineering semi-empirical model and on-site measurements. Fu et al [16,17] used particle image velocimetry (PIV) and a hot wire anemometer system to study the effects of pitch and roll motion of a FOWT on the wake field, and measured the power output of the model. Farrugia et al [18] conducted an experimental study on the aerodynamic characteristics of a wind turbine model and found that the relative speed change between the blade and the incident air flow is the main cause of the aerodynamic characteristics change.…”

Section: Introductionmentioning

confidence: 99%

Study on Aerodynamic Performance and Wake Characteristics of a Floating Offshore Wind Turbine in Wind–Wave Coupling Field

Liang,

Li,

Han

et al. 2024

Sustainability

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Floating offshore wind turbines (FOWTs) exhibit complex motion with multiple degrees of freedom due to the interaction of wind and waves. The aerodynamic performance and wake characteristics of these turbines are highly intricate and challenging to accurately capture. In this study, dynamic fluid body interaction (DFBI) and overset grid technology are employed to investigate the dynamic motion of a 5 MW FOWT. We use the volume of fluid (VOF) method and improved delayed detached eddy simulation (IDDES) model to investigate the aerodynamic performance and wake evolution mechanism for various wave periods and heights. According to the findings, the magnitude of the pitch motion increases with the period and height of the waves, leading to a decrease in both the power output and thrust; the maximum power was reduced by nearly 6.8% compared to a wind turbine without motion. The value of power and thrust reduction varies for different wave periods and heights, and is influenced by the relative speed and pitch angle, which play a crucial role. Wind–wave coupling has a significant impact on the evolution of both wake and vortex structures for FOWT. The wake shape downstream is also dynamically influenced by the waves. In the presence of wind and wave coupling, the interaction between the wind turbine and the wake is heightened, leading to the merger of two unstable vortex rings into a single, larger vortex ring. The research unveils a comprehensive picture of the offshore wind energy dynamics and wake field, which holds immense significance for the design of floating wind turbines and the optimization of wind farm layout.

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In-phase and out-of-phase pitch and roll oscillations of model wind turbines within uniform arrays

Cited by 14 publications

References 32 publications

Onset of wake meandering for a floating offshore wind turbine under side-to-side motion

Onset of wake meandering for a floating offshore wind turbine under side-to-side motion

Wake steering of multirotor wind turbines

Study on Aerodynamic Performance and Wake Characteristics of a Floating Offshore Wind Turbine in Wind–Wave Coupling Field

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