NUMERICAL STUDY OF DYNAMIC CHARACTERISTICS FOR OFFSHORE WIND TURBINE UNDER COMPLEX ATMOSPHERIC INFLOW

With the great development of wind energy technology, the blades of wind turbine have gradually developed to large-scale, which makes the real and complex atmospheric inflow have more and more significant impacts on the operating performance of wind turbines. The numerical simulation of bottom-fixed offshore wind turbine under neutral complex atmospheric inflow is performed to study the dynamic responses of wind turbine under that complex inflow. A precursor simulation method based on large eddy simulations is used to generate the complex atmospheric inflow, and the actuator line model is combined to model the wind turbine blades. The numerical results are compared with the uniform inflow condition, and the results are focusing on the analysis of aerodynamic performance and the dynamic characteristics of rotor and blade root. The numerical results show that the large-scale low-velocity airflow in the neutral and complex atmospheric inflow is responsible for the lower output of wind turbine aerodynamic power in a long period time. In addition, the high turbulence intensity characteristics of the neutral and complex atmospheric inflow lead to the significant increase of varying amplitude and standard deviation of wind turbine aerodynamic power. The standard deviation of rotor thrust increased to 53 times of the uniform inflow condition, and the maximum value, root mean square and standard deviation of yaw moment increased to 10, 4.4 and 4.3 times of uniform inflow condition, because of the disturbance of the neutral and complex atmospheric inflow. The standard deviation values of flapwise shear force and bending moment reach up to 2 and 4.6 times of uniform inflow condition, respectively, caused by the collective effects between the inhomogeneity of the velocity vertical distribution and the large-scale low-velocity plume structures near the hub height.