Advances in Model Scale Testing of Floating Offshore Wind Turbines Utilizing the W2 Wind/Wave Basin

2016 ◽  
Author(s):  
Matthew J. Fowler ◽  
Andrew J. Goupee ◽  
Anthony M. Viselli
Keyword(s):  
Wind Turbines ◽  
Wind Wave ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Model Scale ◽  
Floating Offshore Wind Turbines ◽  
Wave Basin

Numerical Prototyping of Floating Offshore Wind Turbines: Virtual Operation in Real Environmental Conditions

2020 ◽  
Author(s):  
Daniel Milano ◽  
Christophe Peyrard ◽  
Matteo Capaldo
Keyword(s):  
Wind Turbines ◽  
Wind Wave ◽  
Fatigue Analysis ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Wave Direction ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Wave Conditions

Abstract The numerical fatigue analysis of floating offshore wind turbines (FOWTs) must account for the environmental loading over a typical design life of 25 years, and the stochastic nature of wind and waves is represented by design load cases (DLCs). In this statistical approach, combinations of wind speeds and directions are associated with different sea states, commonly defined via simplified wave spectra (Pierson-Moskowitz, JONSWAP), and their probability of occurrence is identified based on past observations. However, little is known about the difference between discretizing the wind/wave direction bins into (e.g.) 10deg bins rather than 30deg bins, and the impact it has on FOWT analyses. In addition, there is an interest in identifying the parameters that best represent real sea states (significant wave height, peak period) and wind fields (profile, turbulence) in lumped load cases. In this context, the aim of this work is to better understand the uncertainties associated to wind/wave direction bin size and to the use of metocean parameters as opposed to real wind and sea state conditions. A computational model was developed in order to couple offshore wind turbine models with realistic numerical metocean models, referred to as numerical prototype due to the highly realistic wind/wave conditions in which it operates. This method allows the virtual installation of FOWTs anywhere within a considered spatial domain (e.g. the Mediterranean Sea or the North Sea) and their behaviour to be evaluated in measured wind and modelled wave conditions. The work presented in this paper compares the long-term dynamic behaviour of a tension-leg platform (TLP) FOWT design subject to the numerical prototype and to lumped load cases with different direction bin sizes. Different approaches to representing the wind filed are also investigated, and the modelling choices that have the greatest impact on the fidelity of lumped load cases are identified. The fatigue analysis suggests that 30deg direction bins are sufficient to reliably represent long-term wind/wave conditions, while the use of a constant surface roughness length (as suggested by the IEC standards) seems to significantly overestimate the cumulated damage on the tower of the FOWT.

Wind/Wave Misalignment Effects on Mooring Line Tensions for a Spar Buoy Wind Turbine

2018 ◽  
Author(s):  
Luigia Riefolo ◽  
Fernando del Jesus ◽  
Raúl Guanche García ◽  
Giuseppe Roberto Tomasicchio ◽  
Daniela Pantusa
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Wave ◽  
Offshore Wind ◽  
Mooring Line ◽  
Ultimate Limit State ◽  
International Electrotechnical Commission ◽  
Wave Loads ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

The design methodology for mooring systems for a spar buoy wind turbine considers the influence of extreme events and wind/wave misalignments occurring in its lifetime. Therefore, the variety of wind and wave directions affects over the seakeeping and as a result the evaluation of the maxima loads acting on the spar-buoy wind turbine. In the present paper, the importance of wind/wave misalignments on the dynamic response of spar-type floating wind turbine [1] is investigated. Based on standards, International Electrotechnical Commission IEC and Det Norske Veritas DNV the design of position moorings should be carried out under extreme wind/wave loads, taking into account their misalignments with respect to the structure. In particular, DNV standard, in ‘Position mooring’ recommendations, specifies in the load cases definition, if site specific data is not available, to consider non-collinear environment to have wave towards the unit’s bow (0°) and wind 30° relative to the waves. In IEC standards, the misalignment of the wind and wave directions shall be considered to design offshore wind turbines and calculate the loads acting on the support structure. Ultimate Limit State (ULS) analyses of the OC3-Hywind spar buoy wind turbine are conducted through FAST code, a certified nonlinear aero-hydro-servo-elastic simulation tool by the National Renewable Energy Laboratory’s (NREL’s). This software was developed for use in the International Energy Agency (IEA) Offshore Code Comparison Collaborative (OC3) project, and supports NREL’s offshore 5-MW baseline turbine. In order to assess the effects of misaligned wind and wave, different wind directions are chosen, maintaining the wave loads perpendicular to the structure. Stochastic, full-fields, turbulence simulator Turbsim is used to simulate the 1-h turbulent wind field. The scope of the work is to investigate the effects of wind/wave misalignments on the station-keeping system of spar buoy wind turbine. Results are presented in terms of global maxima determined through mean up-crossing with moving average, which, then, are modelled by a Weibull distribution. Finally, extreme values are estimated depending on global maxima and fitted on Gumbel distribution. The Most Probable Maximum value of mooring line tensions is found to be influenced by the wind/wave misalignments. The present paper is organized as follows. Section ‘Introduction’, based on a literature study, gives useful information on the previous studies conducted on the wind/wave misalignments effects of floating offshore wind turbines. Section ‘Methodology’ describes the applied methodology and presents the spar buoy wind turbine, the used numerical model and the selected environmental conditions. Results and the corresponding discussion are given in Section ‘Results and discussion’ for each load case corresponding to the codirectional and misaligned wind and wave loads. Results are presented and discussed in time and frequency domains. Finally, in Section ‘Conclusion’ some conclusions are drawn.

scholarly journals A Fully Coupled Computational Fluid Dynamics Method for Analysis of Semi-Submersible Floating Offshore Wind Turbines Under Wind-Wave Excitation Conditions Based on OC5 Data

2018 ◽  
Vol 8 (11) ◽  
pp. 2314 ◽  
Author(s):  
Yin Zhang ◽  
Bumsuk Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Wave ◽  
Offshore Wind ◽  
Wave Excitation ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Fully Coupled

Accurate prediction of the time-dependent system dynamic responses of floating offshore wind turbines (FOWTs) under aero-hydro-coupled conditions is a challenge. This paper presents a numerical modeling tool using commercial computational fluid dynamics software, STAR-CCM+(V12.02.010), to perform a fully coupled dynamic analysis of the DeepCwind semi-submersible floating platform with the National Renewable Engineering Lab (NREL) 5-MW baseline wind turbine model under combined wind–wave excitation environment conditions. Free-decay tests for rigid-body degrees of freedom (DOF) in still water and hydrodynamic tests for a regular wave are performed to validate the numerical model by inputting gross system parameters supported in the Offshore Code Comparison, Collaboration, Continued, with Correlations (OC5) project. A full-configuration FOWT simulation, with the simultaneous motion of the rotating blade due to 6-DOF platform dynamics, was performed. A relatively heavy load on the hub and blade was observed for the FOWT compared with the onshore wind turbine, leading to a 7.8% increase in the thrust curve; a 10% decrease in the power curve was also observed for the floating-type turbines, which could be attributed to the smaller project area and relative wind speed required for the rotor to receive wind power when the platform pitches. Finally, the tower-blade interference effects, blade-tip vortices, turbulent wakes, and shedding vortices in the fluid domain with relatively complex unsteady flow conditions were observed and investigated in detail.

scholarly journals DESIGN OF A 3D PHYSICAL AND NUMERICAL EXPERIMENT ON FLOATING OFF-SHORE WIND TURBINES

2012 ◽  
Vol 1 (33) ◽  
pp. 67 ◽  
Author(s):  
Giuseppe Roberto Tomasicchio ◽  
Elvira Armenio ◽  
Felice D'Alessandro ◽  
Nuno Fonseca ◽  
Spyros A. Mavrakos ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Preliminary Test ◽  
Offshore Wind ◽  
Mooring Lines ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Wave Basin ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Smoothed Particle Hydrodynamics Method

The knowledge of the behavior of floating offshore wind turbines (W/T) under wave and/or wind action remains one of the most difficult challenges in offshore engineering which is mostly due to the highly non-linear response of the structure. The present study describes the design process of a 3D physical experiment to investigate the behavior of the most promising structure technology of floating W/T: spar buoy (SB) and tension leg platform (TLP) under different meteo conditions. In order to properly design the two W/T models, the following topics have been analyzed: mooring lines, mass distribution, appropriate scaling factor and data relative to the geometrical characteristics, wave basin dimensions and wind and waves conditions. In addition, the Smoothed Particle Hydrodynamics method (SPH) (Monaghan 1994) has been considered to simulate the 3D behavior of a floating offshore W/T. In particular, the SPH, calibrated and verified on the basis of the experimental observations, may represent a reliable tool for preliminary test of changes in the floater geometry.

Design and Testing of Scale Model Wind Turbines for Use in Wind/Wave Basin Model Tests of Floating Offshore Wind Turbines

2013 ◽  
Author(s):  
Matthew J. Fowler ◽  
Richard W. Kimball ◽  
Dale A. Thomas ◽  
Andrew J. Goupee
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Model Tests ◽  
Full Scale ◽  
Offshore Wind ◽  
Scale Model ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Wave Basin ◽  
Scale Design

Model basin testing is a standard practice in the design process for offshore floating structures and has recently been applied to floating offshore wind turbines. 1/50th scale model tests performed by the DeepCwind Consortium at Maritime Research Institute Netherlands (MARIN) in 2011 on various platform types were able to capture the global dynamic behavior of commercial scale model floating wind turbine systems; however, due to the severe mismatch in Reynolds number between full scale and model scale, the strictly Froude-scaled, geometrically similar wind turbine underperformed greatly. This required significant modification of test wind speeds to match key wind turbine aerodynamic loads, such as thrust. To execute more representative floating wind turbine model tests, it is desirable to have a model wind turbine that more closely matches the performance of the full scale design. This work compares the wind tunnel performance, under Reynolds numbers corresponding to model test Froude-scale conditions, of an alternative wind turbine designed to emulate the performance of the National Renewable Energy Laboratory (NREL) 5 MW turbine. Along with the test data, the design methodology for creating this wind turbine is presented including the blade element momentum theory design of the performance-matched turbine using the open-source tools WT_Perf and XFoil. In addition, a strictly Froude-scale NREL 5 MW wind turbine design is also tested to provide a basis of comparison for the improved designs. While the improved, performance-matched turbine was designed to more closely match the NREL 5 MW design in performance under low model test Reynolds numbers, it did not maintain geometric similitude in the blade chord and thickness orientations. Other key Froude scaling parameters, such as blade lengths and rotor operational speed, were maintained for the improved designs. The results of this work support the development of protocols for properly designing scale model wind turbines that emulate the full scale design for Froude-scale wind/wave basin tests of floating offshore wind turbines.

Pitch Angle Control of Floating Offshore Wind Turbines by H∞ Control

2014 ◽  
Vol 134 (8) ◽  
pp. 1096-1103 ◽  
Author(s):  
Sho Tsujimoto ◽  
Ségolène Dessort ◽  
Naoyuki Hara ◽  
Keiji Konishi
Keyword(s):  
Wind Turbines ◽  
Pitch Angle ◽  
Offshore Wind ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines

scholarly journals Impact of Typhoons on Floating Offshore Wind Turbines: A Case Study of Typhoon Mangkhut

2021 ◽  
Vol 9 (5) ◽  
pp. 543
Author(s):  
Jiawen Li ◽  
Jingyu Bian ◽  
Yuxiang Ma ◽  
Yichen Jiang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Safety Evaluation ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Motion Response ◽  
Offshore Wind Turbines ◽  
Floating Offshore Wind Turbines ◽  
Coupling Motion

A typhoon is a restrictive factor in the development of floating wind power in China. However, the influences of multistage typhoon wind and waves on offshore wind turbines have not yet been studied. Based on Typhoon Mangkhut, in this study, the characteristics of the motion response and structural loads of an offshore wind turbine are investigated during the travel process. For this purpose, a framework is established and verified for investigating the typhoon-induced effects of offshore wind turbines, including a multistage typhoon wave field and a coupled dynamic model of offshore wind turbines. On this basis, the motion response and structural loads of different stages are calculated and analyzed systematically. The results show that the maximum response does not exactly correspond to the maximum wave or wind stage. Considering only the maximum wave height or wind speed may underestimate the motion response during the traveling process of the typhoon, which has problems in guiding the anti-typhoon design of offshore wind turbines. In addition, the coupling motion between the floating foundation and turbine should be considered in the safety evaluation of the floating offshore wind turbine under typhoon conditions.

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