Study On Dynamic Performance Of Floating Offshore Wind Turbine With Elastic Actuator Line Theory

Offshore wind farms come into peopled sight with the gradual popularity of onshore wind farms.It becomes to be attention that the offshore wind power,because of the strong wind on the ocean,not taking up the land resource,and small noise pollution.The wind turbine works mainly on the floating platform on the ocean.The motion of the floating offshore wind turbine will be caused by the randomness ocean environment.As a result,the output power will be different from that of the onshore one,and the loading will get more complicated.Therefore,it is very difficult to analyze the performance of the floating offshore wind turbine and need a simplified method to solve this problem.In this research,the aerodynamic performance and blade structure characteristics of the Spar-type floating offshore wind turbine are computed and analyzed by the extension pack of OpenFOAM called turbinesFoam.Firstly,the basic theory of the actuator line method and the use of the turbinesFoam are introduced.The accuracy of the turbinesFoam is verified with NREL 5MW wind turbine,Then the wake of the single wind turbine and the force on the blade are analyzed briefly,and the area of the wake recovery is summarized too.The computational efficiency of the actuator line method,which is a speediness algorithm,are compared with STAR-CCM+.Secondly,the aerodynamic performance of double wind turbine arranged on a line is studied.The rotate speed of the wind turbine and the separate distance of the two turbines are optimized respectively.7 times diameters of the rotor is validated as the best distance.With such separate distance,the upstream turbine is not affected by the downstream one,while the output and the thrust of the downstream wind turbine are greatly attenuated and the forces are more unstable.Thirdly,the theory and the solution method of the blade aeroelasticity is introduced,and a simplified way is proposed called elastic actuator line method.Compared with NREL and without aeroelasticity result,the relative error is small.Besides,the influence of the aeroelasticity is less on the aerodynamic characteristics off the wind turbine,but the forces on the blade is greater.Also,the aeroelasticity stability of the blade is analyzed.Finally,the elastic actuator line method is used to simulate the aerodynamic performance of the Spar-type floating offshore wind turbine with given motion.And the feasibility of the method is verified too.With the given motion of the surge and pitch,the output power and the thrust of the wind turbine change periodically,and the wake vortex structure will also be disturbed.This research of the wind turbine simulating will give a simplified model and as a reference in engineering.