|
|
|
| Registros recuperados: 58 | |
|
|
| Maganga, Fabrice; Germain, Gregory; Facq, Jean-valery; Gaurier, Benoit; Rivoalen, Elie; Pinon, Grégory. |
| Le fonctionnement d’une hydrolienne est régi par les caractéristiques de l’écoulement incident. Cet article présente les résultats d’une étude expérimentale visant à déterminer les effets du taux de turbulence de l’écoulement ambiant sur le fonctionnement d’une hydrolienne et le sillage généré. Les essais expérimentaux ont été réalisés dans la veine hydrodynamique à surface libre de l’Ifremer, dont on peut faire varier le taux de turbulence de l’écoulement de 5 à 25%. Le prototype utilisé est une turbine tri-pales à axe horizontal de 0,7 m de diamètre (échelle 1/30). Des cartes de vitesses moyennes, de taux de turbulence, mais également d’énergie cinétique turbulente et de contrainte de cisaillement ont été obtenus à partir de mesures par vélocimétrie... |
| Tipo: Text |
|
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00022/13355/10386.pdf |
| |
|
| |
|
|
| Guillou, Sylvain; Filipot, Jean-francois; Thiebot, Jérôme; Germain, Gregory; Chaplain, Nicolas; Ikhennicheu, Maria; Duarte, Rui; Gaurier, Benoit; Bourgoin, Adrien; Mercier, Philippe; Ata, Riadh; Laverne, Jérôme; Benhamadouche, Sofiane; Pieterse, Aline; Maisondieu, Christophe; Poizot, Emmanuel; Poirier, Jean-charles; Auvray, Cedric; Droniou, Elois; Arramounet, Valentin; Pinon, Grégory. |
| Tidal turbine will be installed in area with high current and high turbulence level. A characterisation of this last is required. The aim of the project THYMOTE is to characterize and understand the generation of eddies from smaller to several tens of meters. Three technics are used: Numerical modelling, Physical modelling, field measurements. Physical and numerical modelling show clearly the appearance of the eddies close to the bottom in presence of dunes or rocks and their motion towards the free surface. |
| Tipo: Text |
|
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00479/59091/61729.pdf |
| |
|
|
| Ikhennicheu, Maria; Germain, Gregory; Druault, Philippe; Gaurier, Benoit. |
| In high flow velocity areas like those suitable for tidal applications, turbulence intensity is high and flow variations may have a major impact on tidal turbines behaviour. Large boils that can be observed at the sea surface are emitted from the sea floor and may interact with the tidal turbines. These boils have then to be characterized. The Reynolds number, based on the rugosity height and the mean flow velocity, is rather high in this context: Re ¼ 2:5 107. For that purpose, experiments are carried out in a flume tank with Re as high as achievable in Froude similitude (in the tank: Re ¼ 2:5 105 and Fr ¼ 0:23) in order to study coherent flow structures emitted behind seabed obstacles. The obstacle is here a canonical square wall-mounted cylinder chosen... |
| Tipo: Text |
Palavras-chave: Turbulence; Experimental trials; Wall-mounted cylinder; PIV; LDV; POD; Lamb-Oseen. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00494/60527/64189.pdf |
| |
|
|
| Delacroix, Sylvain; Germain, Gregory; Gaurier, Benoit; Billard, Jean-yves. |
| Bubble sweep-down is a significant issue for the oceanographic vessels, which affect the acoustic surveys. Experimental trials, carried out in the Ifremer wave and current circulating tank on a 1/30 model of the Pourquoi pas?, are presented. The results demonstrate that this kind of experimental facility is well suited to study the phenomenon of bubble sweep-down encountered around the bow of a ship under specific conditions. From these results, two kinds of bubble clouds formation have been observed and analysed: bubble clouds generated by vortex shedding and breaking waves. The vortex shedding bubble clouds appear randomly in all the configurations tested, even without waves or motions. This phenomenon is due to the interaction between the turbulent flow... |
| Tipo: Text |
Palavras-chave: Bubble sweep-down; Experimental trials; Ship motions; Bow waves. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00335/44578/44315.pdf |
| |
|
|
| Gaurier, Benoit; Cebron, David; Germain, Gregory. |
| A model using wake oscillators is developed to predict the 2D motion in a transverse plan of a rigid cylinder in a flow. This model of the wake dynamics is validated on a single cylinder for which we consider both transverse and in-line response. The good agreement between the model and the experimental results allows to use this model as a simple computation tool in the prediction of 2D Vortex-Induced Vibrations (VIV) and after futher development Wake-Induced Oscillations (WIO) effects. |
| Tipo: Text |
|
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/00023/13431/10438.pdf |
| |
|
|
| Gaurier, Benoit; Germain, Gregory; Pinon, G. |
| Until now, no pan-European nor worldwide consensus on appropriate test methodologies and practices have yet been implemented in order to carry out standard laboratory tests. For performance test (in laboratory as well as in-situ), the measurement of the upstream flow velocity is required to calculate kinetic energy, especially when the turbulence intensity is high. These flow fluctuations affect significantly the performance and fatigue behaviour of tidal turbines. However, for a good accuracy the upstream flow measurement needs to be performed in a synchronous way with the turbine parameters. In this paper, we study the time and space correlation between velocity measurements and turbine parameters in order to evaluate and improve the specifications given... |
| Tipo: Text |
|
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00461/57308/59865.pdf |
| |
|
|
| Gaurier, Benoit; Germain, Gregory; Facq, Jean-valery; Johnstone, C.m.; Grant, A.d.; Day, A.h.; Nixon, E.; Di Felice, F.; Costanzo, M.. |
| One key step of the industrial development of a tidal energy device is the testing of scale prototype devices within a controlled laboratory environment. At present, there is no available experimental protocol which addresses in a quantitative manner the differences which can be expected between results obtained from the different types of facilities currently employed for this type of testing. As a consequence, where differences between results are found it has been difficult to confirm the extent to which these differences relate to the device performance or to the test facility type. In the present study, a comparative ”Round Robin” testing programme has been conducted as part of the EC FP VII MaRINET program in order to evaluate the impact of... |
| Tipo: Text |
Palavras-chave: ”Round Robin” Test; Experimental Trials; Marine Current Energy; Horizontal Axis Marine Turbine. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00270/38163/36298.pdf |
| |
|
| |
|
|
| Gaurier, Benoit; Ikhennicheu, Maria; Druault, Philippe; Germain, Gregory; Facq, Jean-valery; Pinon, Grégory. |
| In high flow velocity areas like those suitable for marine energy application, bathymetry variations create strong velocity fluctuations in the water column. Experiments showed that wide cylindrical obstacles generate large velocity fluctuations, like those measured at sea. In order to study the effects of these fluctuations on the turbine behaviour, an experimental set-up has been developed in the circulating tank of Ifremer in Boulogne-sur-mer by positioning a cylinder and a turbine in its wake. Simultaneous PIV measurements give access to the flow velocity upstream of the turbine. Velocity and efforts are compared in terms of cross-correlation, coherence and their spectral content is studied. Results show that the turbine loads follow velocity... |
| Tipo: Text |
|
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00482/59334/62112.pdf |
| |
|
| |
|
|
| Carlier, Clement; Pinon, Gregory; Mycek, Paul; Gaurier, Benoit; Germain, Gregory; Rivoalen, Elie. |
| The development of marine current turbines arrays still needs nowadays many studies among which we can find the study of interactions between devices. In order to highlight these interactions effects, experiments were carried out in the IFREMER’s (Boulogne-sur-Mer) flume tank. Those experiments used 3-bladed horizontal axis marine current turbines prototypes, regulated in rotation speed. To complete these experiments, a three-dimensional numerical tool is developed at the LOMC (Université du Havre) to simulate one or more turbines in a free upstream current. We present hereafter the numerical and experimental results obtained in the scope of the study of elementary interaction between two turbines axially aligned with the upstream current. |
| Tipo: Text |
|
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00247/35806/34320.pdf |
| |
|
|
| Delacroix, Sylvain; Germain, Gregory; Billard, Jean-yves; Gaurier, Benoit; Facq, Jean-valery; Bacchetti, Thomas. |
| The bubble sweep-down phenomenon around the hull of scientific vessels leads to a disruption of the acoustic waves emitted by the sonars, and a loss of productivity during the acoustic surveys. Numerical or experimental tools used to study this phenomenon still have limitations, mainly due to scale effects on bubbles generation. An innovative method in a circulating tank, using numerical simulations and a motions generator, has been developed. Two mechanisms of air entrainment have been described, as well as the influence of waves characteristics and turbulence on bubbles generation. |
| Tipo: Text |
|
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00247/35807/34321.pdf |
| |
|
| |
|
|
| 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 |
|
| Ano: 2007 |
URL: http://archimer.ifremer.fr/doc/00023/13439/10447.pdf |
| |
|
|
| Duran Medina, Olmo; Schmitt, Francois; Calif, Rudy; Gaurier, Benoit; Germain, Gregory. |
| From measurements obtained at high level frequency over a long period of time, we aim to determine the different characteristics of the flow situated in the IFREMER (French Research Institute for Exploration of the Sea) wave and current flume tank in Boulogne-Sur-Mer. This 2 data measured with a LDV (Laser Doppler Velocimetry) allows to get the characteristics of turbulence and the incident velocity fluctuations. The well-controlled conditions in the flume and the high sampling frequency of LDV system will give us a good estimate of the different flow characteristics such as dissipation, the Reynolds number, the injection scales, Taylor and Kolmogorov. The objective is to place the marine current turbine in this flow and then to study the influence of... |
| Tipo: Text |
|
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00247/35814/34329.pdf |
| |
|
|
| Kervella, Youen; Germain, Gregory; Gaurier, Benoit; Facq, Jean-valery; Bacchetti, Thomas. |
| Les futures zones d’implantation des parcs hydroliens en mer sont caractérisées par des courants de forte intensité et des taux de turbulence importants. Cette turbulence de l’écoulement est susceptible d’altérer le comportement des hydroliennes, à la fois en termes de production d’énergie mais aussi de fatigue structurelle. Afin de déterminer l’influence de la turbulence ambiante sur les effets d’interaction entre hydroliennes, des essais expérimentaux ont été effectués dans un bassin à houle et courant, sur des maquettes d’hydroliennes tri-pales à axe horizontal, régulées en vitesse de rotation. Les interactions entre trois hydroliennes placées sur deux rangées (deux hydroliennes sur la rangée amont et une sur la rangée aval, ou inversement) ont été... |
| Tipo: Text |
Palavras-chave: Énergie marine; Hydroliennes; Turbulence; Effets d'interaction; Essais expérimentaux.. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00212/32342/30782.pdf |
| |
|
|
| Kervella, Youen; Germain, Gregory; Gaurier, Benoit; Facq, Jean-valery; Cayocca, Florence; Lesueur, Patrick. |
| Oyster tables are artificial obstacles which are laid over muddy or sandy-muddy floors in intertidal areas. This study aims to show the current modifications related to the presence of the oyster table thanks to LDV measurement in a flume tank. Boundary layer development in different geometric configuration is underlined and suggests some important areas of velocity decrease and sediment transport modification. Shear stresses are also calculated near the bottom and around the table. The total shear stress in the water column exhibits an important increase when the flow passes through the oyster table, hence a flow energy decrease through dissipation. This study helps to understand the reasons for the increased sedimentation observed in some natural sites. |
| Tipo: Text |
|
| Ano: 2009 |
URL: http://archimer.ifremer.fr/doc/00022/13359/10388.pdf |
| |
|
|
| Mallat, Bachar; Germain, Gregory; Billard, Jean-yves; Gaurier, Benoit. |
| The bubble sweep-down phenomenon around oceanographic research vessels generates acoustic disturbances. A specific experimental protocol in a wave and current circulating tank is used to study this phenomenon around a 1/30 scale ship model in a configuration with current, waves and ship motions. 3D visualizations of the bubble clouds and Stereo-PIV (Particle Image Velocimetry) measurements results, both obtained in the bow vicinity of the ship model, are presented in this paper. The behaviour of the breaking wave with bubble generation is studied and the spatial evolution of the bubble clouds is investigated. It is demonstrated that the bubble cloud generation is mainly conditioned by the ascending vertical velocity of the flow near the bow. It is observed... |
| Tipo: Text |
Palavras-chave: Bubble sweep-down; Breaking wave; Bow wave; Fluid-structure interaction; Flume tank. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00453/56423/58534.pdf |
| |
| Registros recuperados: 58 | |
|
|
|
