Study On Aerodynamic Performance Of Offshore Floating Wind Turbine

With the rapid development of the national economy and a substantial increase inelectricity consumption, how to protect the power supply will become a new topic. As a greenenergy, ocean wind power, which has been widely developed and utilized, arises more andmore attention from the world. When exploiting wind energy in deep water, conventionalfixed foundations are difficult to adapt to the requirements of deep-sea environment. And theusing of floating foundations will be an inevitable choice. But the offshore floating windturbine system should not only endure the load caused by wind, but also the load from wavesand currents. The6DOF movements of floating foundation, caused by waves and currents,can non-negligibly affect the performance characteristics of wind turbine. So how to predictthe aerodynamic characteristics of wind turbines in this environment is particularly important.In addition, the turbulence characteristics of the offshore wind resources has a significanteffect, which is further amplified because of the cube relationship between the output powerand wind speed, on floating wind turbine power system, especially the performance windturbine. So much more attention should be paid.The statistical properties and affecting factors of turbulent wind, described by thestatistical parameters, have been analyzed in this paper at first. And then based on the vonKarman spectrum the turbulence wind in front of wind turbine disk has been simulated byspectral representation method. Subsequently, classical blade element momentum (BEM)theory has been elaborated and the limitations, improved by some corresponding correctionmodel, of the classical BEM have been studied. According to the revised classical BEM thewind turbine of Unsteady Aerodynamic Experiments which were conducted by United StatesRenewable Energy Laboratory experiments has been simulated. And calculated results havebeen compared with experimental data to examine the accuracy of classical BEM theory.According to the characteristic of floating wind turbine, five sets of coordinates wereused to describe the whole system. Then the main formulas of unsteady BEM theory werededucted. Dynamic wake model and yaw model has been introduced respectively to deal withthe effect of time delay of flow and wake misalignment. By analyzing and comparing of thecalculated results the characteristics of unsteady BEM theory have been studied in this thesis.Then the performance of wind turbine in turbulent wind was calculated using unsteady BEM theory and the results have been compared with the steady wind conditions to analyze theimpact of wind turbulence. Finally, considering the impact caused by the movements offloating foundation to the inflow velocity and orientation of the wind turbine, the movementsof floating foundation have been put into the wind turbine performance calculations, usingunsteady BEM method. And the regulation of performance of wind turbine was studied bychanging the form or parameters of movementsThe results show that BEM theory is competent to model the performance of windturbine. The performance of wind turbine in turbulence wind will acutely fluctuate. And themovements of floating foundation have a serious impact on the performance of wind turbine.While the amplitude and initial values of movements are the key parameters.