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Parmeggiani S.,Wave Dragon Ltd. | Parmeggiani S.,University of Aalborg | Muliawan M.J.,Norwegian University of Science and Technology | Gao Z.,Norwegian University of Science and Technology | And 2 more authors.
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2012

The Wave Dragon Wave Energy Converter is ready to be up-scaled to commercial size. The design and feasibility analysis of a 1.5 MW pre-commercial unit to be deployed at the DanWEC test center in Hanstholm, Denmark, is currently ongoing. With regard to the mooring system, the design has to be carried out numerically, through coupled analyses of alternative solutions. The present study deals with the preliminary hydrodynamic characterization of Wave Dragon needed in order to calibrate the numerical model to be used for the mooring design. A hydrodynamic analysis of the small scale model in the frequency domain is performed by the software HydroD, which uses WAMIT as core software. The quadratic damping term, accounting for the viscous effect, is determined through an iterative procedure aimed at matching numerical predictions on the mooring tension, derived through time domain coupled analysis, with experimental results derived from tank tests of a small scale model. Due to the complex geometry of the device, a sensitivity analysis is performed to discuss the influence of the mean position on the quality of the numerical predictions. Good correspondence is achieved between the experimental and numerical model. The numerical model is hence considered reliable for future design applications. Copyright © 2012 by ASME.

Parmeggiani S.,Wave Dragon Ltd. | Parmeggiani S.,University of Aalborg | Kofoed J.P.,Wave Dragon Ltd. | Friis-Madsen E.,Wave Dragon Ltd.
Energies | Year: 2013

The paper presents the results of an experimental study identifying the response of a 1.5 MW Wave Dragon to extreme conditions typical of the DanWEC test center. The best strategies allowing for a reduction in the extreme mooring tension have also been investigated, showing that this is possible by increasing the surge natural period of the system. The most efficient strategy in doing this is to provide the mooring system with a large horizontal compliance (typically in the order of 100 s), which shall be therefore assumed as design configuration. If this is not possible, it can also be partly achieved by lowering the floating level to a minimum (survivability mode) and by adopting a negative trim position. The adoption of the design configuration would determine in a 100-year storm extreme mooring tensions in the order of 0.9 MN, 65% lower than the worst case experienced in the worst case configuration. At the same time it would lead to a reduction in the extreme motion response, resulting in heave and pitch oscillation heights of 7 m and 19° and surge excursion of 12 m. Future work will numerically identify mooring configurations that could provide the desired compliance. © 2013 by the authors.

Parmeggiani S.,Wave Dragon Ltd. | Parmeggiani S.,University of Aalborg | Kofoed J.P.,University of Aalborg | Friis-Madsen E.,Wave Dragon Ltd.
Energies | Year: 2013

An overtopping model specifically suited for Wave Dragon is needed in order to improve the reliability of its performance estimates. The model shall be comprehensive of all relevant physical processes that affect overtopping and flexible to adapt to any local conditions and device configuration. An experimental investigation is carried out to update an existing formulation suited for 2D draft-limited, low-crested structures, in order to include the effects on the overtopping flow of the wave steepness, the 3D geometry of Wave Dragon, the wing reflectors, the device motions and the non-rigid connection between platform and reflectors. The study is carried out in four phases, each of them specifically targeted at quantifying one of these effects through a sensitivity analysis and at modeling it through custom-made parameters. These are depending on features of the wave or the device configuration, all of which can be measured in real-time. Instead of using new fitting coefficients, this approach allows a broader applicability of the model beyond the Wave Dragon case, to any overtopping WEC or structure within the range of tested conditions. Predictions reliability of overtopping over Wave Dragon increased, as the updated model allows improved accuracy and precision respect to the former version. © 2013 by the authors.

Eskilsson C.,Chalmers University of Technology | Palm J.,Chalmers University of Technology | Kofoed J.P.,University of Aalborg | Friis-Madsen E.,Wave Dragon Ltd
Renewable Energies Offshore - 1st International Conference on Renewable Energies Offshore, RENEW 2014 | Year: 2015

The Wave Dragon is a floating Wave Energy Converter (WEC) working by the overtopping principle. The overtopping discharge has been determined by model scale experiments in wave basins. In the present study we numerically simulate the overtopping behavior of the Wave Dragon device using a VOF based incompressible Euler/Navier-Stokes solver in the Open FOAM® framework. We present simulations of: (i) a complete sea state for different crest heights, and (ii) regular waves for different wave conditions and crest heights. The simulations compare reasonably well with the experimental data, albeit the irregular wave simulations predict a larger overtopping discharge than observed in the experiments. © 2015 Taylor & Francis Group, London.

Parmeggiani S.,Wave Dragon Ltd. | Parmeggiani S.,University of Aalborg | Kofoed J.P.,University of Aalborg | Friis-Madsen E.,Wave Dragon Aps.
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2011

The Wave Dragon Wave Energy Converter is currently facing a precommercial phase. At this stage of development a reliable overtopping model is highly required, in order to predict the performance of the device at possible deployment locations. A model formulation derived for an overtopping device with general geometry has been used so far. The paper presents an updated formulation drawn through the tank testing of a scaled model the Wave Dragon. The sensitivity analysis of the main features influencing the overtopping flow led to an updated model formulation which can be specifically suited for the Wave Dragon. Copyright © 2011 by the International Society of Offshore and Polar Engineers (ISOPE).

Agency: European Commission | Branch: FP7 | Program: MC-ITN | Phase: PEOPLE-2007-1-1-ITN | Award Amount: 3.58M | Year: 2008

The proposed action builds strongly up on the logics of its predecessor with the same name. The overall objective is to create a pool of specialised wave energy research professionals to support an emerging industry in a field with a very strong anticipated growth and no dedicated existing training curriculum. Although most jobs can be done being a trained engineer in one of the adjacent fields, the existance of interdisciplinary skilled researchers trained in direct connection to the technology development is vital for successful development. In the predecessor, almost all fellows where immediatley absorbed by industrial players in the field or continued research in the host institution. The work plan for WAVETRAIN 2 fellows is specifically directed towards a wide range of challenges that industrial-scale wave energy implementation faces in the present situation, with some bias towards technical issues, from hydrodynamic and PTO (Power-Take-Off) design, to instrumentation issues and energy storage and cost reduction show to be critical for successful deployment. On the other hand, also non-technical barriers, typically less tangible difficulties related to legal issues (licensing, conflicts of use, EIA procedures, grid connection, regional differences) and the non-sufficient representation of socio-economic benefits of the sector, will be dealt with, as they are seen as a major obstacel for fast implementation on a European scale. The methodology to achieve the desired results is to provide (i) in-depth training in one applied research topic (host institution), (ii) good interdisciplinary background and understanding of industry environment (short courses and secondments), and (iii) active participation in wave power plant testing in the sea (some of the profiles; others: site visits). The in-depth training at the host institution will be incorporated in relevant research topics, where typically an advance the state-of-the-art is expected.

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