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- Chatzigiannakou, Maria Angeliki, et al.
(författare)
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Offshore deployments of wave energy converters by Uppsala University, Sweden
- 2019
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Ingår i: Marine Systems and Ocean Technology. - : Springer Science and Business Media LLC. - 1679-396X .- 2199-4749. ; 14:2-3, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- Ocean can provide an inexhaustible amount of energy. Many marine energy converters have been developed but most of them have not surpassed the experimental phase due to the high costs in installation, operation, and maintenance. Since 2002 Uppsala University has developed and deployed several units of wave energy converters of various designs. The Uppsala University wave energy converter concept consists of a linear generator directly connected to a point absorber buoy that is mounted on a concrete gravity foundation. Uppsala University deployments have been carried out using different deployment vessels and methods. Three main methods were utilized for these deployments that are discussed in terms of cost, manpower, and time efficiency. Depending on the desired outcome—multiple- or single-device deployment, low budget, etc.—one of the proposed methods can be used for the optimal outcome.
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| 2. |
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| 3. |
- Chatzigiannakou, Maria Angiliki, et al.
(författare)
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Offshore Deployments of Wave Energy Converters by Seabased Industry AB
- 2017
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Ingår i: Journal of Marine Science and Engineering. - : MDPI AG. - 2077-1312. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- Since 2008, Seabased Industry AB (SIAB) has manufactured and deployed several units of wave energy converters (WECs) of different design. The WECs are linear generators with point absorber buoy systems that are placed on the seabed, mounted on a gravitation concrete foundation. These deployments have taken place in different areas, using different deployment vessels. Offshore deployments of WECs and underwater substations have so far been complicated procedures, that were both expensive and time-consuming. The focus of this paper is to discuss these deployments in terms of economy and time efficiency, as well as safety. Because seven vessels have been used to facilitate the deployments, an evaluation on the above basis is carried out for them. The main conclusions and certain solutions are presented for the various problems encountered during these deployments and the vessel choice is discussed. It is found that the offshore deployment process can be optimized in terms of cost, time efficiency and safety with a careful vessel choice, use of the latest available technologies and detailed planning and organizing.
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| 4. |
- Chen, WenChuang, et al.
(författare)
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Numerical modelling of a point-absorbing wave energy converter in irregular and extreme waves
- 2017
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Ingår i: Applied Ocean Research. - : Elsevier BV. - 0141-1187 .- 1879-1549. ; 63, s. 90-105
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Tidskriftsartikel (refereegranskat)abstract
- Based on the Navier-Stokes (RANS) equations, a three-dimensional (3-D) mathematical model for the hydrodynamics and structural dynamics of a floating point-absorbing wave energy converter (WEC) with a stroke control system in irregular and extreme waves is presented. The model is validated by a comparison of the numerical results with the wave tank experiment results of other researchers. The validated model is then utilized to examine the effect of wave height on structure displacements and connection rope tension. In the examined cases, the differences in WEC’s performance exhibited by an inviscid fluid and a viscous fluid can be neglected. Our results also reveal that the differences in behavior predicted by boundary element method (BEM) and the RANS-based method can be significant and vary considerably, depending on wave height.
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| 7. |
- Dolguntseva, Irina, 1981-, et al.
(författare)
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Risk based estimation of failure in a steel wire used for the wave energy converter connection line
- 2014
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Konferensbidrag (refereegranskat)abstract
- The wave energy converter being developed at Uppsala University is of a point absorber type utilizing heaving motion of waves with a direct driven linear generator power take off. The point absorber, a buoy, is placed on the sea surface and is connected to the translator by a connection line. The connection line service life is of large importance for the lifetime of the entire device. Steel wire used as the connection line should be chosen to withstand loadings with different amplitude and frequency. In the present study, the risk of failure in the connection line is estimated.
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| 8. |
- Francisco, Francisco, 1985-, et al.
(författare)
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Use of Multibeam and Dual-Beam Sonar Systems to Observe Cavitating Flow Produced by Ferryboats : In a Marine Renewable Energy Perspective
- 2017
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Ingår i: Journal of Marine Science and Engineering. - : MDPI. - 2077-1312. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- With the prospect to deploy hydrokinetic energy converters in areas with heavy boat traffic, a study was conducted to observe and assess the depth range of cavitating flow produced by ferryboats in narrow channels. This study was conducted in the vicinity of Finnhamn Island in Stockholm Archipelago. The objectives of the survey were to assess whether the sonar systems were able to observe and measure the depth of what can be cavitating flow (in a form of convected cloud cavitation) produced by one specific type of ferryboats frequently operating in that route, as well as investigate if the cavitating flow within the wake would propagate deep enough to disturb the water column underneath the surface. A multibeam and a dual-beam sonar systems were used as measurement instruments. The hypothesis was that strong and deep wake can disturb the optimal operation of a hydrokinetic energy converter, therefore causing damages to its rotors and hydrofoils. The results showed that both sonar system could detect cavitating flows including its strength, part of the geometrical shape and propagation depth. Moreover, the boat with a propeller thruster produced cavitating flow with an intense core reaching 4 m of depth while lasting approximately 90 s. The ferry with waterjet thruster produced a less intense cavitating flow; the core reached depths of approximately 6 m, and lasted about 90 s. From this study, it was concluded that multibeam and dual-beam sonar systems with operating frequencies higher than 200 kHz were able to detect cavitating flows in real conditions, as long as they are properly deployed and the data properly analyzed.
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