OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine

Robertson, Amy; Wendt, Fabian; Jonkman, Jason; Popko, Wojciech; Dagher, Habib J.; Gueydon, Sébastien; Qvist, Jacob; Vittori, Felipe; Azcona, José; Uzunoğlu, Emre; Soares, C. Guedes; Harries, Rob; Yde, Anders; Galinos, Christos; Hermans, K.W.; Vaal, Jacobus Bernardus De; Bozonnet, Pauline; Bouy, Ludovic; Bayati, Ilmas; Bergua, Roger; Galván, Josean; Mendikoa, I.; Sánchez, Carlos Barrera; Shin, Hyunkyoung; Oh, Sehoon; Molins, Climent; Debruyne, Yannick

doi:10.1016/j.egypro.2017.10.333

Cited by 225 publications

(195 citation statements)

References 5 publications

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“…Nonetheless, regarding the progressive availability of information and incidence on the research field, NREL's 5MW OWT has captivated significant pertinence. It has been the reference turbine for offshore code comparison studies OC3, OC4, and more recently OC5 …”

Section: Owt Sn Fatigue Designmentioning

confidence: 99%

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Analysis of long‐term loading characterization for stress‐cycle fatigue design

2019

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The present paper discusses the application of stress‐cycle (SN) fatigue design procedures for offshore wind turbines, applied to the tower and substructure, and emphasizing the long‐term loading characterization. Three main methodologies are compared to assess SN fatigue long‐term design, direct scale‐up of loads and cycles to the design lifetime, probability fit for the loading distribution, and truncation and fit of the tail region. Different characteristic SN slopes are researched. The comprehensive comparison developed shows that limited interest exists in increasing the complexity of the loading assessment for SN fatigue design. In particular, the notion of representative sample has key influence on the fatigue calculations. Probability analysis techniques are not an adequate substitute of a representative sample. If definition of a representative sample for design is unpractical due to its large cost, direct scale‐up of cycles from a time t to a larger time T can be applied with uncertainty assessment. Bootstrapping of load ranges is implemented to tackle the limitations imposed by approaching a design time much larger than the evaluated time. It takes advantage of the fact that SN fatigue design is a statistical problem of mean value. Bootstrapping proved to be an efficient estimator of uncertainty with relatively constant confidence bounds, of particular interest to perform SN fatigue design with small samples. New insights on its application for fatigue design are presented. Due to its simple application and nonparametric character, it can be applied in combination with other techniques, such as extrapolation of loads and cycles.

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Section: Owt Sn Fatigue Designmentioning

confidence: 99%

“…It has been the reference turbine for offshore code comparison studies OC3, OC4, and more recently OC5. 48 Operational simulations of 600 seconds, or 10 minutes, are considered to compute the results. Large simulation times may be considered in the analysis, instead of running multiple shorter simulations.…”

Section: Owt Simulationmentioning

confidence: 99%

Analysis of long‐term loading characterization for stress‐cycle fatigue design

2019

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“…Phase II of the Offshore Code Comparison Collaboration Continuation (OC4) project was chosen for the aero‐hydrodynamic coupling. The same configuration illustrated in Figure A has been also used in the Phase II of the Offshore Code Comparison Collaboration Continuation, with Correction (OC5) project, which focuses on validating tools (code‐to‐data comparisons). The 1/50th scale model of the OC4 DeepCwind semisubmersible platform shown in Figure B was previously tested at the Maritime Research Institute Netherlands .…”

Section: Numerical Test Model: Semisubmersible Platform Specificationmentioning

confidence: 99%

A CFD study of coupled aerodynamic‐hydrodynamic loads on a semisubmersible floating offshore wind turbine

Tran

Kim

2017

Wind Energy

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The prediction of dynamic characteristics for a floating offshore wind turbine (FOWT) is challenging because of the complex load coupling of aerodynamics, hydrodynamics, and structural dynamics. These loads should be accurately calculated to yield reliable analysis results in the design phase of a FOWT. In this study, a high-fidelity fluid-structure interaction simulation that simultaneously considers the influence of aero-hydrodynamic coupling due to the dynamic motion of a FOWT has been conducted using computational fluid dynamics based on an overset The dynamic influence of aero-hydro-structure interaction due to the coupled wind-wave loads on a floating offshore wind turbine (FOWT) is still not well understood. Various experimental floating substructures in both wave basin facilities and ocean coasts have been constructed or are in the planning stages throughout the world. 1-7 The current status of both of them is well described in the previous studies. [2][3][4] From the viewpoint of engineering, compared to a full-scale test on an ocean field, a wave basin test for a scaled-down model can reduce risk, cost, and uncertainties in the design. Dynamic characteristics of floating structure from a wave basin test can be approximately evaluated. However, its results are highly influenced by purpose of tests and quality of experiment equipment (eg, installed sensors and wind and wave generation quality). Moreover, previous experimental works did not adequately consider the same material, construction methods, or deployment method as the full-scale system. 7 In particular, a scaled-down model experiment in a wave basin inherently has limitations on the simultaneous satisfaction of both Froude and Reynolds scaling laws. [8][9][10][11] The scaled-down model is typically scaled by the dimensionless Froude number to ensure the similarity of platform hydrodynamic whereas the tip-speed ratio and wind speed to wave celerity ratio between scales is maintained to entirely consistent with Froude scaling. 8 However, an experiment on a FOWT is usually more expensive than a sophisticated design tool, which is preferred for cost-effective solutions during the design process. Therefore, sophisticated modeling tools must be developed to accurately simulate the complex multiphysical phenomena induced by aero-hydro-multibody dynamic coupling for a FOWT. 1 The dynamic characteristics of FOWTs have been properly analyzed by fully coupled aero-hydro-servo-elastic dynamic approaches. [12][13][14] However, the unsteady aerodynamic calculation in these approaches was performed using the well-known blade element momentum (BEM)

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“…The solvers show a reasonable agreement, especially on the motions of the platform, but large discrepancies can be observed on the mooring and tower base loads for instance. Experimental measurements have also been confronted to numerical results of the semi‐submersible HAWT . Given the level of uncertainty of experimental measurements and of small scale testing, it is however difficult to conclude on the quality of the agreement of the numerical solvers with the observed physics at full scale.…”

Section: Introductionmentioning

confidence: 99%

Impact of aerodynamic modeling on seakeeping performance of a floating horizontal axis wind turbine

Leroy

Gilloteaux

Lynch³

et al. 2019

Wind Energy

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Over the last decade, several coupled simulation tools have been developed in order to design and optimize floating wind turbines (FWTs). In most of these tools, the aerodynamic modeling is based on quasi‐steady aerodynamic models such as the blade element momentum (BEM). It may not be accurate enough for FWTs as the motion of the platform induces highly unsteady phenomena around the rotor. To address this issue, a new design tool has been developed coupling a seakeeping solver with an unsteady aerodynamic solver based on the free vortex wake (FVW) theory. This tool is here compared with the reference code FAST, which is based on the BEM theory in order to characterize the impact of the aerodynamic model on the seakeeping of a floating horizontal axis wind turbine (HAWT). Aerodynamic solvers are compared for the case of the free floating NREL 5MW HAWT supported by the OC3Hywind SPAR. Differences obtained between the models have been analyzed through a study of the aerodynamic loads acting on the same turbine in imposed harmonic surge and pitch motions. This provides a better understanding of the intrinsic differences between the quasi‐steady and unsteady aerodynamic solvers. The study shows that differences can be observed between the three aerodynamic solvers, especially at high tip speed ratio (TSR) for which unsteady aerodynamic phenomena and complex wake dynamics occur. Observed discrepancies in the predictions of the FWT dynamic response can raise issues when designing such a system with a state‐of‐the‐art design tool.

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OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine

Cited by 225 publications

References 5 publications

Analysis of long‐term loading characterization for stress‐cycle fatigue design

Analysis of long‐term loading characterization for stress‐cycle fatigue design

A CFD study of coupled aerodynamic‐hydrodynamic loads on a semisubmersible floating offshore wind turbine

Impact of aerodynamic modeling on seakeeping performance of a floating horizontal axis wind turbine

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