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| Registros recuperados: 20 | |
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| Gaurier, Benoit; Germain, Gregory; Le Boulluec, Marc; Giry, Eric; Fontaine, Emmanuel. |
| Vortex-Induced Vibrations (VIV) are well-known and related to the majority of cylindrical structures subjected to strong winds or currents. The VIV limit the lifetime of the structure because they increase the forces and so the fatigue. When several structures of this kind are put together in close interaction, the wake effects (Wake Induced Oscillations - WIO) sometimes involve strong instabilities. If these structures are flexible or mobile, oscillations of several diameters can be observed and collisions can occur ([4] & [6]). Such structures are widespread in the oil industry where the extraction of oil in deep water can be done by means of risers. In some cases, risers are connected to a floating support called FPSO (Floating Production Storage... |
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| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-6584.pdf |
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| Salic, Tom; Charpentier, Jean Frédéric; Benbouzid, Mohamed; Le Boulluec, Marc. |
| The offshore wind resource has huge energy potential. However, wind turbine floating structures have to withstand harsh conditions. Strong wind and wave effects combine to generate vibrations, fatigue, and heavy loads on the structure and other elements of the wind turbine. These structural problems increase maintenance requirements and risk of failure, while reducing availability and energy production. Another challenge for wind energy is to reduce production costs in order to be competitive with other alternatives. From the control point of view, the objective of lowering costs can be achieved by operating the turbine close to its optimum point of operation under partial load, guaranteeing reliability by reducing structural loads and regulating the power... |
| Tipo: Text |
Palavras-chave: Wind energy; Floating offshore wind turbine; Control; State of art review. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00588/69991/67899.pdf |
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| Le Boulluec, Marc; Ohana, Jeremy; Chalony, Sebastien; Tancray, Aurelien; Le Gall, Clément; Fourestier, Gaspard; Santagostini, Timothée; Ercolanelli, Julien; Cueff, Quentin; Raoul, Samuel. |
| A method for reducing the roll of a ship consists in placing a tank whose liquid content is animated by free surface sloshing motions. The dynamic coupling with the vessel is studied experimentally at reduced model in a test tank. Numerical modeling under perfect fluid and viscous fluid assumptions make it possible to approach the measured responses. |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00392/50352/51049.pdf |
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| Rey, Vincent; Guinot, Florent; Le Boulluec, Marc. |
| The aim of this large scale basin experiment on wave current interactions was a better understanding of vertical velocity profiles changes due to progressive surface waves. The instrumentation deployed including wave gauges, pressure sensors and current meters allowed precise measurements along the basin. In particular, the effect of waves on the homogenization of vertical profile was measured, and the effect of current on the underestimate of wave height from bottom mounted pressure sensors was demonstrated. However, the current flow without wave was bi-dimensional and weakly sheared, and no study on the current instability as observed in previous experiment could be achieved. |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00170/28171/26405.pdf |
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| Fourestier, Gaspard; Santagostini, Timothée; Le Boulluec, Marc; Magaldi, Philippe; Scolan, Yves-marie. |
| One type of low head hydropower plant is studied. This solution, based on a bathtub vortex, is called the gravitational vortex hydropower. It consists on a turbine placed at the center of the vortex which allows to harvest the kinetic energy [1]. As a first step, the bathtub vortex is studied without the turbine, in the supercritical flow regime. A numerical model has been performed using OpenFOAM 2.2.2. A two phases approach, using the volume of fluid method has been chosen. Simulations are mostly done without any modelling of turbulent phenomena (laminar model). In order to validate the numerical approach, an experimental campaign is carried out. The experimental data are compared qualitatively and quantitatively to the values extracted from the... |
| Tipo: Text |
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| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00392/50354/51053.pdf |
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| Maisondieu, Christophe; Le Boulluec, Marc. |
| When considering deployment of wave energy converters at a given site, it is of prime importance from both a technical and an economical point of view to accurately assess the total yearly energy that can be extracted by the given device. Especially, to be considered is the assessment of the efficiency of the device over the widest span of the sea-states spectral bandwidth. Hence, the aim of this study is to assess the biases and errors introduced on extracted power classically computed using spectral data derived from analytical functions such as a JONSWAP spectrum, compared to the power derived using actual wave spectra obtained from a spectral hindcast database. |
| Tipo: Text |
Palavras-chave: Wave energy; Wave spectra; Hindcast; Resource assessment. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00347/45799/45445.pdf |
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| Klinghammer, Christian; Prevosto, Marc; Le Boulluec, Marc; Perignon, Yves. |
| Up to this day, design recommendations or practices for floating structures, such as DNVs RP-C205 and F205 for example, do not account for the existence of low frequency free Infragravity (IG) waves. These are low-frequency water waves which represent an additional excitation for (moored) floating structures. In this study, the influence of free IG waves on moored floating structures response is investigated and compared to second-order low-frequency wave forces, as the standard low frequency excitation, for two selected important free IG events in 2013 and 2014 at the SEM-REV (Site d'Experimentation En Mer - Récupération de l'Energie des Vagues) test site near Le Croisic, Pays-de-la-Loire, France. The wave forces and motion response for two example... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00384/49584/50094.pdf |
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| Filipot, Jean-francois; Prevosto, Marc; Maisondieu, Christophe; Le Boulluec, Marc; Thomson, Jim. |
| This work presents the analysis of wave and turbulence measurements collected at a tidal energy site. A new method is introduced to produce more consistent and rigorous estimations of the velocity fluctuations power spectral densities. An analytical function is further proposed to fit the observed spectra and could be input to the numerical models predicting power production and structural loading on tidal turbines. Another new approach is developed to correct for the effect of the Doppler noise on the high frequencies power spectral densities. The analysis of velocity time series combining wave and turbulent contributions demonstrates that the turbulent motions are coherent throughout the water column, rendering the wave coherence-based methods not... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00254/36537/35074.pdf |
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| Fonseca, Nuno; Pessoa, Joao; Ribeiro E Silva, Sergio; Le Boulluec, Marc; Ohana, Jeremy. |
| The paper presents the results of an experimental program with a scaled model of the UGEN wave energy converter (WEC). This concept has been developed by IST (Instituto Superior Técnico) based on a floating body with a U tank filled with water. The amount of water accounts for 40% of the floater displacement. The sway, heave and roll motion of the floating body coupled to the water oscillating in the U tube induce an oscillating air flow on the upper part of the U tank from one branch to the other through a circular tube. The aim of the device is to capture the air flow energy through a turbine. The natural period of the water in the U tank (circa 1.25 s) and of the resulting floating body natural rolling period (circa 1.9 s) are separated in such a way... |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00170/28173/26407.pdf |
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| Rouault, Marie Christine; Molin, Bernard; Le Boulluec, Marc; Petrie, François. |
| An experimental campaign was previously reported on the slow-drift motion of a rectangular barge moored in irregular beam seas. The 24 m long false bottom of the basin is raised and inclined at a slope of 5% from 1.05m below the free surface to 0.15m above (see figure 1). The barge is moored in different water depths (from 54 cm to 21 cm). The measured slowdrift component of the sway motion is compared with state of the art calculations based on Newman approximation. The principal results are, for the beam sea configuration: - at 54 cm depth: good agreement between the experimental results and the Newman simulation - at 21 cm depth: the Newman calculation overpredicts the forces. When the flat bottom set-down contribution is added, the calculated value is... |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00170/28174/26408.pdf |
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| Gaurier, Benoit; Germain, Gregory; Le Boulluec, Marc; Giry, Eric; Fontaine, E.. |
| The interactions between several cylinders placed in close proximity are the subject of many studies, because of the strong repeated loads that they create on these structures. For flexible or mobile structures, the wake effects can produce large amplitudes motions. These displacements can be higher than those considered during the lock-in of a single cylinder, to reach several diameters. Depending the initial spacing, they lead sometimes to clashes with potentially high intensity, between the cylinders. To better understand these phenomena, an experimental study was carried out, bearing on the interaction between two models of tensioning buoy supporting hybrid risers. After checking that the models used were able to correctly reproduce the movements... |
| Tipo: Text |
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| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00023/13439/10447.pdf |
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| Harnois, V.; Weller, Sam D.; Johanning, L.; Thies, P. R.; Le Boulluec, Marc; Le Roux, Dominique; Soule, Veronique; Ohana, Jeremy. |
| The design of wave energy mooring systems is challenging: overdesign incurs a significant cost penalty, underdesign may lead to a premature failure and incorrect design could reduce the power production. Consequently, compliant mooring systems are being developed for wave energy applications. This paper presents tank test results for a scale model of the buoy and mooring used at the SouthWest Mooring Test Facility (SWMTF), an offshore facility developed to conduct long-term sea trials for wave energy device moorings. A compliant three leg catenary mooring system using Nylon ropes in the water column is investigated. Preliminary static, quasi-static, decay, regular and irregular wave tests were conducted on the 1:5 scale model, using the Ifremer basin in... |
| Tipo: Text |
Palavras-chave: Wave energy converter; Tank tests; Numerical model; Highly dynamic mooring system; Fibre rope. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00233/34375/35785.pdf |
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| Registros recuperados: 20 | |
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