The Dynamic Response of an Offshore Wind Turbine With Realistic Flexibility to Breaking Wave Impact

Ridder, E. J. de; Aalberts, Pieter; Berg, Jur van den; Buchner, Bas; Peeringa, J.M.

doi:10.1115/omae2011-49563

Cited by 9 publications

(6 citation statements)

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“…The numerical values for each event are given in Table 5. These observations suggest, as was also found in de Ridder et al (2011), that not taking into account the 2 nd mode of the structure when assessing ULS leads to underestimation of the total response. For these 21 events, we also note that the maximum response is negative, i.e.…”

Section: Contributions To the Total Responsesupporting

confidence: 76%

“…In addition to higher order hydrodynamic loads, breaking wave events have been a major concern for offshore structures. Both de Ridder et al (2011) and Bredmose et al (2013) carried out experiments on a bottom-fixed responding structure (as opposed to a stiff structure) whose characteristics were similar to those of an idling extra-large wind turbine (i.e. with the blades completely pitched to feather to limit the aerodynamic loading) and found that breaking waves could lead to extreme accelerations of the nacelle.…”

Section: Introductionmentioning

confidence: 99%

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Experimental results of a multimode monopile offshore wind turbine support structure subjected to steep and breaking irregular waves

et al. 2017

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We present experimental data from MARIN on a bottom-fixed offshore wind turbine mounted on a monopile in intermediate water depth subjected to severe irregular wave conditions. Two models are analysed: the first model is fully flexible and its 1 st and 2 nd eigenfrequencies and 1 st mode shape are representative of those of a full-scale turbine.This model is used to study the structural response with special focus on ringing and response to breaking wave events.The second model is stiff and is used to analyse the hydrodynamic excitation loads, in particular the so-called secondary load cycle. The largest responses are registered when the second mode of the structure is triggered by a breaking wave on top of a ringing response. In such events, the quasi-static response accounts for between 40 and 50% of the total load, the 1 st mode response between 30 and 40%, and the 2 nd mode response up to 20%. A statistical analysis on the occurrences and characteristics of the secondary load cycle shows that this phenomenon is not directly linked to ringing.

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Section: Contributions To the Total Responsesupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Experimental results of a multimode monopile offshore wind turbine support structure subjected to steep and breaking irregular waves

et al. 2017

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“…Hence in these cases, hydrodynamic tests can be carried out without the rotor as long as the influence of the rotor mass properties is correctly represented (e.g. De Ridder et al, 2011).…”

Section: Uncoupled Testsmentioning

confidence: 99%

Hydrodynamic modelling of marine renewable energy devices: A state of the art review

et al. 2015

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a b s t r a c tThis paper reviews key issues in the physical and numerical modelling of marine renewable energy systems, including wave energy devices, current turbines, and offshore wind turbines. The paper starts with an overview of the types of devices considered, and introduces some key studies in marine renewable energy modelling research. The development of new International Towing Tank Conference (ITTC) guidelines for model testing these devices is placed in the context of guidelines developed or under development by other international bodies as well as via research projects. Some particular challenges are introduced in the experimental and numerical modelling and testing of these devices, including the simulation of Power-Take-Off systems (PTOs) for physical models of all devices, approaches for numerical modelling of devices, and the correct modelling of wind load on offshore wind turbines. Finally, issues related to the uncertainty in performance prediction from model test results are discussed.

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“…More extensive testing was carried out at MARIN [11]. A 1:30 flexible model was constructed to represent the mass, stiffness, and first two modes of a 6MW wind turbine with 6 m diameter at the waterline (full scale).…”

Section: Facilitymentioning

confidence: 99%

Experimental and numerical investigations of monopile ringing in irregular finite-depth water waves

Bachynski

Kristiansen

Thys

2017

Applied Ocean Research

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In storm conditions, nonlinear wave loads on monopile offshore wind turbines can induce resonant ringing-type responses. Efficient, validated methods which capture such events in irregular waves in intermediate or shallow water depth conditions are needed for design. Dedicated experiments and numerical studies were performed toward this goal. The extensive experimental campaign at 1:48 scale was carried out for Statoil related to the development of the Dudgeon wind farm, and included both a rigid model and a flexible, pitching-type, single degree-of-freedom model. Twenty 3-hour duration realizations for 4 sea states and 2 water depths were tested for each model. A high level of repeatability in ringing events was observed. Uncertainties in the experimental results were critically examined.The stochastic variation in the 3-hour maximum bending moment at the sea bed was significantly larger than the random variation in repetition tests, and highlighted the need for a good statistical basis in design. Numerical simulations using a beam element model with a modified Morison wave load model and 2nd order wave kinematics gave reasonable prediction of the ringing response of the flexible model, and of the measured excitation forces on the rigid model in the absence of slamming. The numerical model was also used to investigate the sensitivity of the responses with respect to damping and natural period. A simple single degree-of-freedom model was shown to behave similarly to a fully flexible model when considering changes in natural frequency and damping.

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The Dynamic Response of an Offshore Wind Turbine With Realistic Flexibility to Breaking Wave Impact

Cited by 9 publications

References 0 publications

Experimental results of a multimode monopile offshore wind turbine support structure subjected to steep and breaking irregular waves

Experimental results of a multimode monopile offshore wind turbine support structure subjected to steep and breaking irregular waves

Hydrodynamic modelling of marine renewable energy devices: A state of the art review

Experimental and numerical investigations of monopile ringing in irregular finite-depth water waves

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