Aeroelastic Analysis Of Offshore Floating Wind Turbine Blades

With the increasingly serious environmental pollution,global warming,and the increasing consumption of non-renewable energy,countries around the world are looking for clean,nonpolluting and renewable energy.As a kind of renewable new energy,wind energy has the characteristics of large reserves,wide distribution and no pollution.It has attracted wide attention from all countries in the world.Especially the development and utilization of offshore wind energy,which has the advantages of high wind speed and low turbulence effect,has become an important direction of wind energy research in the future.As one of the most important equipments for offshore wind energy development,the research of aeroelastic performance of offshore floating wind turbines is of great significance.Firstly,through a trapezoidal wing model,the correctness of simulation is verified by comparing the results of numerical simulation and experimental research.The comparison shows that the lift coefficient curve,drag coefficient curve and lift-drag ratio curve obtained by numerical simulation and experiment have the same change trend under the same condition.In the lift coefficient curve,the lift coefficient decreases abruptly after the stall Angle,and in the drag coefficient curve,the drag coefficient increases abruptly after the stall Angle.The error between numerical simulation and experimental research is less than 5%,indicating the feasibility of numerical simulation research and the correctness of the analysis method.Secondly,taking the 5MW wind turbine published by NREL as the model,the aerodynamic performance of fixed wind turbine and floating wind turbine blades is studied by numerical simulation.The results show that the design errors of horizontal thrust,output power and NREL of fixed wind turbines are not more than 5% under different wind speeds,which indicates the validity of the three-dimensional numerical model.Then the influence of the motion amplitude and period of the floating platform on the aerodynamic performance of the floating wind turbine is analyzed.With the increase of the motion amplitude of the floating platform,the horizontal thrust and output power of the wind turbine have been significantly increased,which is due to the change of the incident wind speed of the blade caused by the motion amplitude,and the change of the wind speed has a significant impact on the aerodynamic performance of each cross-section airfoil of the fan blade.With the increase of the motion period of the floating platform,the aerodynamic performance of the wind turbine is limited.This is because under normal sea conditions,the variation range of wave cycle is relatively limited.Finally,the elastic properties of wind turbine blades are studied by one-way fluid-structure coupling method.The results show that the amplitude of the floating platform has a great influence on the elastic performance of the wind turbine blades,while the motion period of the floating platform has a limited influence on the elastic performance of the wind turbine blades.Under different wind speeds,the stress on 20%~80% of the blade is larger,which is the main area to bear bending moments,and also where the section of the airfoil varies greatly.Therefore,in the design of the blade,the rib plate should be strengthened in the blade area.