Aeroelastic Instability Characteristics Analysis Of 10MW Floating Offshore Wind Turbine Blades

Floating offshore wind turbines are the main way to develop and utilize deep-sea wind energy resources.Floating offshore wind turbines will produce six degrees of freedom movement under the combined action of wind and wave loads.The aeroelastic coupling effect of blades is obviously intensified,and the probability of aeroelastic instability of blades is higher.It is urgent to carry out research on the aeroelastic instability characteristics of floating offshore wind turbine blades.The research results were completed under the support of Huaneng Offshore Wind Power and Smart Energy System Science and Technology Project(Phase Ⅰ),High Efficiency and High Reliability Large-Scale Offshore Wind Turbine and Wind Farm Design Technology Research(No.HNKJ20-H88-01).The main research work and achievements are as follows:(1)Taking the DTU 10MW reference wind turbine as the research object,the aeroelastic-hydrodynamic numerical model of the 10MW floating offshore wind turbine was established based on the modified blade element momentum theory,geometrically exact beam theory and three-dimensional potential flow theory.The aeroelastic response characteristics of blades of the floating offshore wind turbine under steady state conditions are studied,and the aeroelastic instability characteristics of blades of the floating offshore wind turbine under the run-away situation are revealed.(2)The simulation results show that the aeroelastic deformation and fluctuation of the floating offshore wind turbine blades are significantly increased compared with the onshore wind turbines under the combined action of wind and wave loads.The critical rotational speed of blade aeroelastic instability is 7.59%lower than that of onshore wind turbines.The aeroelastic instability of the blade is caused by the coupling of edgewise and torsion.When the aeroelastic instability occurs,the blade will produce large elastic deformation accompanied by severe oscillation.(3)The research results show that the pitch motion of the floating platform has the greatest impact on the aeroelastic response and aerodynamic loading of the floating offshore wind turbine blades,resulting in a significant increase in the thrust of the rotor,the mean and fluctuation of the aeroelastic deformation of the blades.The pitch motion is the main reason that the critical rotational speed of blade aeroelastic instability of floating offshore wind turbines is lower than that of onshore wind turbines.The critical rotational speed of aeroelastic instability of blades is reduced by 7.90%under pitch motion.(4)The simulation research shows that the increase of the significant wave height,spectral peak period,and wind-wave misalignment angle will increase the fluctuation of the rotor thrust and blade aeroelastic deformation of the floating offshore wind turbine to varying degrees.As a result,the blade aeroelastic coupling effect is intensified,and the critical rotational speed of blade aeroelastic instability is decreased.Floating offshore wind turbines have a higher probability of blade aeroelastic instability under harsher sea conditions.