Response of the IEA Wind 15 MW – WindCrete and Activefloat
floating wind turbines to wind and second-order waves

Mahfouz, Youssef; Molins, Climent; Trubat, Pau; Hernández, S.; Vigara, Fernando; Pegalajar‐Jurado, Antonio; Bredmose, Henrik; Salari, Mohammad

doi:10.5194/wes-2021-11

Cited by 11 publications

(16 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The frequencies resulting in the significant far wake meandering fall in the range 0.2 ≤ St ≤ 0.6, although, being lower than the wave frequencies commonly encountered (corresponding to St > 1.0 for the present turbine design), they are within the range of the natural motion frequencies of the floating platform, indicating the importance of considering wake meandering induced by FOWT motion in the design of FOWT farms. For example, the well-studied reference offshore wind turbine platform, the DeepCwind semi-submersible platform (Robertson et al 2014), has natural roll period about 26 s (St ≈ 0.4), which will dominate the platform motion when second-order wave forces are considered (Mahfouz et al 2021). The present work shows that this design may trigger large-amplitude far wake meandering when the platform oscillates at its natural roll frequency under low ambient turbulence.…”

Section: Discussionmentioning

confidence: 79%

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

Dong

Yang

2022

J. Fluid Mech.

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 79%

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

Dong

Yang

2022

J. Fluid Mech.

View full text Add to dashboard Cite

show abstract

“…The largest spectral components are of the same order of magnitude as the standard deviation of the corresponding time series (that stands at 0.16), suggesting that the explanation may stem from the turbine model itself and not from the calculations. This fact was noticed and studied more in-depth in [1] and was attributed to the large inertia of this turbine. The same happens with the remaining DOFs.…”

Section: Fowt Response Spectrum -S Yy (F )mentioning

confidence: 68%

“…No second-order waves nor second-order platform loads were enabled. This method was applied to the WindCrete spar-buoy model developed in the EU-funded COREWIND project [1] using OpenFAST 2.4…”

Section: Methodsmentioning

confidence: 99%

A frequency-time domain method for annual energy production estimation in floating wind turbines

Amaral

Laugesen

Masciola³

et al. 2022

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

A new method is proposed to estimate a floating wind turbine’s annual energy production (AEP) using frequency and time-domain design techniques. The approach demonstrated herein estimates the AEP by performing a convolution between the floating platform response and the response power operators (RPOs) that map the average power produced by the turbine as a function of the amplitude and frequency of the platform motions. One advantage of this approach is that it can be performed early in the conceptual design phase to help discover design space trade-offs between the platform and rotor design. The methodology is applied to the IEA Wind 15 MW WindCrete spar-buoy model using OpenFAST. The RPOs are obtained by prescribing single-DOF platform motions to the turbine with a given amplitude and frequency. This methodology is then validated by comparing the AEP estimation from the RPOs with the AEP estimation from fully-coupled simulations. The results indicate that the method is able to estimate the value of AEP for a realistic sea-state and regular waves. However, further validation is needed as, in the first case, the turbine is moving too little and, in the second case, the contribution of the controller may be dominant.

show abstract

“…The PI collective pitch controller for overrated has been designed using the Ziegler-Nichols approach (Ziegler et al, 1942).…”

Section: Controller Designmentioning

confidence: 99%

Comment on wes-2021-11

2021

View full text Add to dashboard Cite

The EU Horizon 2020 project COREWIND has developed two floating platforms for the new International Energy Agency (IEA) Wind 15 MW reference model. One design -"WindCrete" -is a spar floater, and the other -"Activefloat" -is a semi-submersible floater. In this work the design of the floaters is introduced with their aero-hydro-servo-elastic numerical models, and the responses of both floaters in both static and dynamic simulations are verified against the operational and survival design limits. The static displacements and natural frequencies are simulated and discussed. Additionally, the effects of the mean wave drift forces, and difference second order wave forces on the systems' responses are presented. The increase in the turbine's power capacity to 15MW in IEA Wind model, leads to an increase in inertial forces and aerodynamic thrust force when compared to similar floating platforms coupled to the Danish Technical University (DTU) 10MW reference model. The goal of this work is to investigate the floaters responses at different load cases. The results in this paper suggest that at mild wave loads the motion responses of the 15MW Floating Offshore Wind Turbines (FOWT) are dominated by low frequency forces.Therefore, motions are dominated by the wind forces, and second order wave forces rather than the first order wave forces.After verifying and understanding the models' responses, the two 15MW FOWT reference numerical models are publicly available to be used in the research and development of floating wind energy.

show abstract

Response of the IEA Wind 15 MW – WindCrete and Activefloat floating wind turbines to wind and second-order waves

Cited by 11 publications

References 11 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

A frequency-time domain method for annual energy production estimation in floating wind turbines

Comment on wes-2021-11

Contact Info

Product

Resources

About