Study On The Coupling Effect Of Random Wind And Wave Current On Offshore Wind Turbines

In recent years,offshore wind power has developed rapidly with its advantages of large capacity,high efficiency and stability of power generation,and no occupation of land resources.The following problem is that wind turbines face more complex and variable load environments,so higher requirements are put forward for the rationality of wind turbine structure design.Based on the theory of aerodynamics and hydrodynamics,this paper numerically simulates the actual random load conditions(wind load and wave load)faced by offshore wind turbines,and then imports them into finite element simulation software.Combined with the fluid-solid coupling analysis method,the coupling calculation model of random wind load and wave load on wind turbines is established.According to the calculation results,the wind pressure characteristics,stress distribution law and deformation of the wind turbine surface are analyzed and studied.The main research contents and results are as follows :(1)Based on the wind characteristic theory,random wave theory and wind-generated wave mechanism,the random wind load and wave load of wind turbine are numerically simulated by MATLAB program.By studying and comparing the advantages and disadvantages of harmonic superposition method and linear filtering method,an improved numerical simulation method is proposed and verified by an example.The results show that the improved numerical simulation method can accurately and efficiently simulate random wind load and wave load,and provide external flow field load conditions for subsequent simulation of offshore wind turbines.(2)Taking the 5MW offshore wind turbine published by the US Renewable Energy Commission as the research object,several key structural components(blades,tower,foundation)of the wind turbine are modeled by Solid Works,and then several models are assembled into a whole to obtain a 5MW offshore wind turbine model.The whole machine model is verified by power verification and modal analysis to verify the accuracy and applicability of the model.The verification results show that the whole machine model established in this paper will not resonate under the condition of external excitation source.The natural frequency and modal shape diagram of the wind turbine model are obtained.(3)Based on the fluid-solid coupling theory,the external flow field fluid domain model of random wind load and wave load,the solid domain model of wind turbine and the rotating domain model of wind turbine are established by using ANSYS Workbench.The coupling solution process of flow field domain and solid domain is designed,and the simulation process of the coupling effect of random wind and wave load on wind turbine is completed.The deformation of the wind turbine surface,the stress distribution law,the streamline distribution of the fluid and the flow around the wind turbine are analyzed.The results show that under the action of random wind and wave load,the stress distribution of the upper structure of the sea level at different heights and the area where the wind pressure extreme value exists show certain regularity.The research results have certain reference value for the design of offshore wind turbines in the future.