Building and calibration of a fast model of the SWAY prototype floating wind turbine

Present efforts to verify and validate aero-hydro-servo-elastic numerical simulation tools that predict the dynamic response of a floating offshore wind turbine are primarily limited to code-to-code comparisons or code-to-data comparisons using data from wind-wave basin tests. In partnership with SWAY AS, the National Renewable Energy Laboratory (NREL) installed scientific wind, wave, and motion measurement equipment on the 1/6.5^th-scale prototype SWAY floating wind system to collect data to validate a FAST model of the SWAY design in an open-water condition. Nanyang Technological University (NTU), through a collaboration with NREL, assisted in this validation. This paper shows the use of the results of the SWAY open-water tests to calibrate the numerical FAST model, which will be used for future validation efforts. First, the modeling strategies and development of the FAST model for the SWAY prototype wind turbine are presented, including justification of the modeling assumptions. Next, the model calibration-based on a subset of the free-decay test data-is shown. This process involved tuning properties of the FAST model where uncertainties existed to better match the response of the prototype wind turbine. Finally, limitations of the FAST model and potential areas of improvement of the project are discussed.