Sensitivity of the dynamic response of a multimegawatt floating wind turbine to the choice of turbulence model

Nybø, Astrid; Nielsen, Finn Gunnar; Godvik, Marte

doi:10.1002/we.2712

Cited by 12 publications

(10 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, for the TIMESR model, for pitch and surge, there is a higher energy content at the same frequency (0.003 Hz) as previously mentioned for the wind fields PSD (Section 2.4.4), related to the size of convective cellular structures. The findings on the global motions presented here coincide with the ones from Nybø et al, 17 where the pitch and surge standard deviations for the TIMESR and Kaimal models are found higher compared to the ones from the Mann model, and the opposite is found for the yaw standard deviation.…”

Section: Resultssupporting

confidence: 91%

“…The FL1 tension DEL shows a higher loading for unstable conditions for the Kaimal and TIMESR models compared to the Mann model, especially for the rated wind‐speed scenario. For this scenario, at 12 m/s, and especially for unstable and neutral conditions, these findings for the fairlead tension are consistent with the work from Nybø et al, 17 even though their work focused on a spar‐type FWT. Under neutral and stable conditions, for the below‐ and over‐rated scenarios, the Kaimal, Mann and TIMESR models yield very similar responses.…”

Section: Resultssupporting

confidence: 90%

“…Similarly to what we observe for the TIMESR model fitted to the FINO‐1 measurements, from the PSD of surge and pitch of the 12 m/s scenario (Figure 10, bottom), the higher energy content at around 0.003 Hz is captured by the TIMESR model, but not by the Kaimal and Mann models. Nybø et al 17 found that the surge and pitch standard deviation of the LES model was lower than the Kaimal, TIMESR and Mann models, under neutral conditions, for the cases at and over‐rated wind speeds. When comparing stability conditions at rated wind speed, they also found that under unstable conditions the standard deviation of the LES is very similar to the Kaimal and TIMESR models.…”

Section: Resultsmentioning

confidence: 98%

“…For neutral and stable conditions, for the 7. Nybø et al 17 found that the surge and pitch standard deviation of the LES model was lower than the Kaimal, TIMESR and Mann models, under neutral conditions, for the cases at and over-rated wind speeds. When comparing stability conditions at rated wind speed, they also found that under unstable conditions the standard deviation of the LES is very similar to the Kaimal and TIMESR models.…”

Section: Models Fitted To Les Datamentioning

confidence: 98%

“…Most of the work to date which studies atmospheric stability combined with offshore wind turbines focuses either on the effect of stability on fixed structures, e.g., Nybø et al, 3 or on the effect of the turbulence model and coherence on FWT under neutral conditions, e.g., Bachynski & Eliassen 12 . Doubrawa et al, 9 Nybø et al 17 and Myrtvedt et al 18 studied the effect of atmospheric stability on a spar‐type FWT. The effect of atmospheric stability on the global motions and on the structural response of a semisubmersible FWT has not previously been studied using the Kaimal and Mann models fitted to LES data and point measurements.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Effects of atmospheric stability on the structural response of a 12 MW semisubmersible floating wind turbine

et al. 2022

View full text Add to dashboard Cite

Global dynamic response models used for the design of wind turbines are largely based on neutral stability, which is not representative of real atmospheric conditions. Offshore wind farms, for example, have been seen to experience predominantly unstable conditions, especially at lower wind speeds. In the current work, we use four wind generation models under stable, neutral and unstable atmospheric stability conditions to study the low‐frequency content of the global responses of a semisubmersible floating wind turbine (FWT). To represent the wind fields, we use the Kaimal Spectrum and Exponential Coherence Model (Kaimal), the Mann Spectral Tensor Model (Mann), a point measurement based model (TIMESR) and large‐eddy simulation (LES). At the low‐frequency range, both atmospheric stability and the turbulence wind model significantly affect the response of the FWT. In all the cases studied throughout this paper, the structural response under unstable conditions is higher than under stable or neutral conditions. The TIMESR and the Kaimal models fitted to the FINO‐1 offshore meteorological mast measurements show more similar responses than the Mann model; surge and pitch are higher for the TIMESR and Kaimal models, and yaw is lower. When fitted to LES, TIMESR and Kaimal predict surge and pitch responses closer to LES, but they underestimate the responses related to yaw, opposite to what the Mann model does. The responses are directly related to turbulence intensity and coherence, which are affected by atmospheric stability. Therefore, based on the analyses carried out through this study, the structural analysis of FWT should account for the effect of atmospheric stability.

show abstract

Section: Resultssupporting

confidence: 91%

Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 98%

Section: Models Fitted To Les Datamentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effects of atmospheric stability on the structural response of a 12 MW semisubmersible floating wind turbine

et al. 2022

View full text Add to dashboard Cite

show abstract

Effect of atmospheric stability on the dynamic wake meandering model applied to two 12 MW floating wind turbines

Rivera‐Arreba,

Wise,

Eliassen

et al. 2023

Wind Energy

View full text Add to dashboard Cite

Current global analysis tools for floating wind turbines (FWTs) do not account for the combined effects of atmospheric stability and wakes from neighboring turbines. This work uses the mid‐fidelity dynamic wake meandering model, together with turbulent wind fields generated based on stable, neutral, and unstable atmospheric conditions, to study the low‐frequency content of the global responses of two semisubmersible FWTs separated by eight rotor diameters. Incoming wind fields based on the Kaimal spectrum and exponential coherence model, the Mann spectral tensor model, and a time‐series input‐based turbulence model are used. The respective input parameters for these models are fitted to high‐fidelity large eddy simulation data.In unstable, below‐rated conditions, meandering leads to an increase in the yaw standard deviation of the downwind turbine of almost three times larger than the upwind turbine. Deficit and the upwards wake deflection affect the mean pitch and yaw, especially for the below‐rated wind speed scenario. The mean pitch of the downwind turbine is reduced up to half the mean pitch value of the upwind turbine, whereas the mean yaw changes direction due to the enhanced effect of shear. The effect of meandering on the structural loading is highest on the standard deviation of the tower‐top yaw moment of the downstream turbine, which increases more than 2.2 times compared to the upwind turbine value. Based on these findings, atmospheric stability affects wake deficit and meandering which in turn have a profound effect on the low‐frequency global motions and structural response of floating wind turbines.

show abstract

A Model for Low-Frequency, Anisotropic Wind Fluctuations and Coherences in the Marine Atmosphere

Syed,

Mann

2024

Boundary-Layer Meteorol

View full text Add to dashboard Cite

To assess dynamic loads, large offshore wind turbines need detailed and reliable statistical information on the inflow turbulence. We present a model that includes low frequencies down to $$\sim 1$$ ∼ 1 hr$$^{-1}$$ - 1 using the observed $$S(f) \propto f^{-5/3}$$ S ( f ) ∝ f - 5 / 3 in that range. The presented model contains a parameter representing the anisotropy of the two-dimensional, incompressible turbulence, and it assumes the low-frequency fluctuations to be homogeneous in the vertical direction. Combined with a three-dimensional model for the smaller scales, the model can predict correlations between different points. We have validated the model against two offshore wind data sets: a nacelle-mounted, forward-looking Doppler lidar with four beams at the Hywind Scotland offshore wind farm and sonic anemometer measurements at the FINO1 research platform in the North Sea. One-point auto spectra and two-point cross spectra were calculated after splitting the data into different atmospheric stability classes. The relative strength of the 2D low-frequency fluctuations to the 3D fluctuations was higher under stable conditions. The combined 2D+3D model was able to fit the measured spectra with good accuracy and could then predict the two-point cross spectra, co-coherences, and phase angles between wind fluctuations at different lateral and vertical separations. Good agreement was found between the measured and predicted values, albeit with exceptions. The model can generate stochastic wind fields for investigating wake meandering in wind farms or dynamic loads on floating wind turbines.

show abstract

Sensitivity of the dynamic response of a multimegawatt floating wind turbine to the choice of turbulence model

Cited by 12 publications

References 23 publications

Effects of atmospheric stability on the structural response of a 12 MW semisubmersible floating wind turbine

Effects of atmospheric stability on the structural response of a 12 MW semisubmersible floating wind turbine

Effect of atmospheric stability on the dynamic wake meandering model applied to two 12 MW floating wind turbines

A Model for Low-Frequency, Anisotropic Wind Fluctuations and Coherences in the Marine Atmosphere

Contact Info

Product

Resources

About