The Aerodynamic Analysis Of Spar Type Floating Offshore Wind Turbine

With the development of the offshore wind power technology,the deep-water floating offshore wind turbines(FOWT)have gradually attracted more researchers.As the power and sizes of wind turbines increase,the research on large FOWT has drawn more and more attention.FOWT experience complicated and extreme movements in deep sea environments,and these movements not only lead to complex dynamic responses of wind turbines,but also greatly influence the aerodynamic characteristics.The change of the aerodynamic loads will raise higher requirements on the structural strength and elasticity of the wind turbine blades and have a greater impact on the output power.The drastic change of wake distributions will also influence the aerodynamic characteristics of the downstream wind turbine.Therefore,It is necessary to study the contribution of each motion along each DOFs to optimize the design of FOWT.In the research of the influence factors of the aerodynamic characteristics of the fixed wind turbines,the torque and thrust of the NREL 5MW wind turbine in rated wind speed are calculated,and the calculation precision is improved by trying different parameters.By comparing the optimized torque and thrust results with the reference results,the feasibility of this method is verified.In the research of the effects of pitch motion and surge motion on the aerodynamic characteristics of FOWT,the motions of single degree of freedom(pitching or surging)at different frequencies are simulated,and the aerodynamic load,the limit streamline and the wake vortex distribution at different time point in one period are analyzed.The influence of frequency on these characteristics are also compared.Next,the coupled motion of pitch and surge motion at the same frequency is simulated.The simulation results show that the coupled motion has a different coupled effect on the aerodynamic loads compared with the one-DOF motion.Finally,in the research of the aerodynamic characteristics of the Spar platform supported FOWT that moves freely under uniform wind and regular waves,the average amplitudes and the variation range of amplitudes of the three DOFs(pitching,surging and heaving)motionare compared with that of single DOF motion.The similarities and differences of the output power and shaft thrust of three DOFs motion and the one-DOF motion are analyzed,including the average values and the amplitudes of variation.The influence of the mooring system are considered herein.