Numerical Simulation And Analysis On Aerodynamic Performance Of Offshore Wind Turbine And Hydrodynamics Of Floating Platform

With a large number of demands for energy in modern society, and increasing exploitation and consumption of traditional energy sources, the energy crisis is more and more apparent. People began to look for a way out, so they set their sights on new energy filed. Wind energy, especially offshore wind energy,as a clean, renewable energy sources, which has been fully developed in recent years, has attracted the attention of governments, and becomes an important direction for future energy development. The study of offshore wind turbine is of great importance to offshore wind power development and solving the energy problem in the future.This thesis, taking the Computational Fluid Dynamics(CFD) open source software platform OpenFOAM as a tool, calculate and analyze the aerodynamic performance of offshore wind turbine and hydrodynamic performance of floating platform in waves by using numerical simulation method, as well as initial coupling for impact of offshore wind turbine on floating platform motion response, and directly analyze the three-dimensional viscous flow filed of offshore wind turbine by using the advantage of CFD method,which laid a basis for the overall coupling simulation analysis for future offshore wind turbine foundation.This paper describes two methods for solving the rotational motion of the blade: Multiple reference frame method to solve the problem of steady flow field and sliding mesh method to solve the problem of unsteady flow field. And these two methods are validated respectively by the benchmarks of propeller and American National Renewable Energy Laboratory(NREL) Phase VI wind turbine, which show that the reliability of these two methods.On this basis, the aerodynamic performance of offshore wind turbine has been analyzed. At first, influence of different parameters, such as turbulence models, different computational domain size and yaw angle, to the accuracy of simulation results is analyzed. Then, aerodynamic performance of NREL 5MW offshore wind turbine blade for Phase II of the Code Comparison Collaboration Continuation(OC4) in International Energy Agency(IEA) task 30 is calculated, respectively with multiple reference frame method and sliding mesh method. And in order to study the tower shadow effect, aerodynamic performance of the blade with the tower is analyzed.Finally, naoe-FOAM-SJTU solver which developed by our team based on OpenFOAM platform is used to calculate the forces and motion responses of floating offshore wind turbine platform in waves. By using an equivalent way, the impact of wind turbine is equivalent to a fixed force and torque exerted on the rotating center of platform. The force and motion responses are compared to the platform without the external forces, and analyze the changes of velocity field, pressure field in free surface and pressure distribution on the platform, which display the impact of the wind turbine on the hydrodynamic performance of the platform.