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Title: OC5 Project Phase II: Validation of Global Loads of the DeepCwind Floating Semisubmersible Wind Turbine

This paper summarizes the findings from Phase II of the Offshore Code Comparison, Collaboration, Continued, with Correlation project. The project is run under the International Energy Agency Wind Research Task 30, and is focused on validating the tools used for modeling offshore wind systems through the comparison of simulated responses of select system designs to physical test data. Validation activities such as these lead to improvement of offshore wind modeling tools, which will enable the development of more innovative and cost-effective offshore wind designs. For Phase II of the project, numerical models of the DeepCwind floating semisubmersible wind system were validated using measurement data from a 1/50th-scale validation campaign performed at the Maritime Research Institute Netherlands offshore wave basin. Validation of the models was performed by comparing the calculated ultimate and fatigue loads for eight different wave-only and combined wind/wave test cases against the measured data, after calibration was performed using free-decay, wind-only, and wave-only tests. The results show a decent estimation of both the ultimate and fatigue loads for the simulated results, but with a fairly consistent underestimation in the tower and upwind mooring line loads that can be attributed to an underestimation of wave-excitation forces outside the linearmore » wave-excitation region, and the presence of broadband frequency excitation in the experimental measurements from wind. Participant results showed varied agreement with the experimental measurements based on the modeling approach used. Modeling attributes that enabled better agreement included: the use of a dynamic mooring model; wave stretching, or some other hydrodynamic modeling approach that excites frequencies outside the linear wave region; nonlinear wave kinematics models; and unsteady aerodynamics models. Also, it was observed that a Morison-only hydrodynamic modeling approach could create excessive pitch excitation and resulting tower loads in some frequency bands.« less
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  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Fraunhofer Inst. for Wind Energy and Energy System Technology, Bremerhaven (Germany)
  3. Univ. of Maine, Orono, ME (United States)
  4. Maritime Research Inst., Wageningen (Netherlands)
  5. 4Subsea, Nesbru (Norway)
  6. National Renewable Energy Centre (CENER), Navarra (Spain)
  7. Centre for Marine Technology and Ocean Engineering (CENTEC), Lisbon (Portugal)
  8. DNV GL, Bristol (United Kingdom)
  9. Technical Univ. of Denmark, Lyngby (Denmark)
  10. European Centre of the Netherlands, Petten (Netherlands)
  11. Inst. for Energy Technology (IFE), Kjeller (Norway)
  12. IFP Energies nouvelles, Rueil-Malmaison (France)
  13. PRINCIPIA, Nantes (France)
  14. Politecnico di Milano (Italy)
  15. Siemens PLM, Barcelona (Spain)
  16. Tecnalia, San Sebastian (Spain)
  17. Univ. de Cantabria, Cantabria (Spain). IH Cantabria
  18. Univ. of Ulsan, Ulsan (South Korea)
  19. Univ. of Tokyo (Japan)
  20. Univ. Politecnica de Catalunya (Spain)
  21. WavEC Offshore Renewables, Lisbon (Portugal)
Publication Date:
Report Number(s):
Journal ID: ISSN 1876-6102
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Energy Procedia
Additional Journal Information:
Journal Volume: 137; Journal Issue: C; Journal ID: ISSN 1876-6102
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Water Technologies Office (EE-4W)
Country of Publication:
United States
17 WIND ENERGY; 42 ENGINEERING; floating offshore wind turbine; DeepCwind semisubmersible; numerical modeling; verifcation; validation; IEA Wind
OSTI Identifier: