Fluid Dynamic Performance Of Semi-submersible Floating Offshore Wind Turbine

In the process of continuous development of renewable energy,wind energy is being continuously developed due to its rich resources,wide distribution and convenient and low-cost power generation.Compared with onshore wind energy resources,offshore wind energy resources have the advantages of strong and stable wind speed,small wind shear and no occupation of land,and are developed for human use.As the development and utilization of wind energy resources continue to advance to the deep sea,the development of wind power generators,especially semi-submersible floating wind turbines in the deep sea,has gradually become a hot research direction.Semi-submersible floating fans floating on the sea free surface,and always subject to the impact of ocean waves,it will have a dynamic impact on the electrical power generation,and make the aerodynamic loads on the blades more complex,so semi-submersible floating wind turbine performance analysis and evaluation have great challenges.Therefore,the analysis of fluid performance of semi-submersible floating wind turbine is significantly important for the future development.In this paper,numerical simulation software STAR-CCM+ is used to analyze the aerodynamic performance and hydrodynamic performance of the semi-submersible floating turbine.Firstly,taking NREL 5MW wind turbine as the research object,the UG software is used to model the wind turbine.The thrust force and output power of the wind turbine under static state are simulated.The results have been compared with those of other calculation methods to verify the simulation method.The effects of surge motion and pitch motion on the aerodynamic performance of the blades are analyzed respectively.The rotor thrust and power variations under different motion amplitudes are studied by comparing the airfoil pressure on the blade sections.The wake vortex distribution and velocity distribution have been discussed as well.Secondly,the effect of tower on the aerodynamic performance of the wind turbine is studied.The pressure coefficient of the turbine blade with tower in the case of surge motion and pitch motion is studied respectively.It is found that the presence of tower reduces the pressure coefficient of the leading edge of the airfoil.Thrust and power curve values areless than the case without the tower,Vortex broken phenomenon is detected in the wake by comparing vortex shedding pattern with and without tower.Finally,the six-degree-of-freedom motion of semi-submersible floating turbine foundation is simulated and analyzed under the condition of wave motion.The simulation results are contrasted with the experimental results,which shows the accuracy of the calculation method.The effect of the heave plate and its parameters on the surge,pitch,heave and other motions of the turbine base is also studied.It is found that the installation of heave plate can reduce the response of heave and pitch motion of semi-submersible floating foundation,and the size and shape of heave plate have a corresponding effect on the floating foundation.The whole turbine movement and the aerodynamic response under the wave and wind condition are analyzed.