Numerical Study on Influence of Turbulent and Steady Winds on Coupled Dynamic Response of 6-MW Spar-type FOWT

摘要

Wind turbine tower, Spar-type platform and mooring system of the 6-MW spar-type floating offshore wind turbine (FOWT) are designed in the paper based on a given 6-MW wind turbine. And then the 6-MW FOWT model is established in the fully coupled aero-hydro-servo-elastic simulation tool of FAST. Model validation is conducted firstly. Calculation values of FOWT under combined wind- and wave-induced loads have great agreement with reference values. The factor of simulation length varied from 10min to 3 h is also studied to investigate the influence of simulation length on coupled dynamic response. And results display that the 1 h simulation length is sufficient. And then, comparison between steady wind and turbulent wind is carried out and results illustrate that the maximal response values of mean rotor thrust, mean rotor power, platform pitch motion and fairlead force under the turbulent wind conditions are larger -9.4%, -0.01%, 5.5% and 12.8% than that of the steady wind conditions, respectively. The influence of wind type on the mean rotor power is scarcely. However, the effect of wind type on the response of fairlead force cannot be ignored and should be put more attention on the phenomenon. Also, the platform pitch, surge and heave motion and fairlead force response are compared to investigate the effect of wind turbine on spar-type platform and mooring system tension. And the rotor power, out-of-plane blade tip deflection, nacelle surge acceleration and tower base fore-aft bending moment response are compared to investigate the effect of spar-type platform motion on wind turbine and tower. The results can provide a clear understanding of the wind type influence and interaction influence between the wind turbine and spar-type platform. And it is beneficial to the further study on the FOWT system.