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In this study, the performance of offshore wind turbines at low tip speed ratio (TSR) is studied using computational fluid dynamics (CFD), and the performance of offshore wind turbines at low tip speed ratio (TSR) is improved by revising the blade structure. First, the parameters of vertical axis offshore wind turbine are designed based on the compactness iteration, a CFD simulation model is established, and the turbulence model is selected through simulation analysis to verify the independence of grid and time step. Compared with previous experimental results, it is shown that the two-dimensional simulation only considers the plane turbulence effect, and the simulation turbulence effect performs more obviously at a high tip ratio, while the three-dimensional simulation turbulence effect has well-fitting performance at high tip ratio. Second, a J-shaped blade with optimized lower surface is proposed. The study showed that the optimized J-shaped blade significantly improved its upwind torque and wind energy capture rate. Finally, the performance of the optimized J-blade offshore wind turbine is analyzed.

In this study, the structure of the trailing edge of the vertical axis offshore wind turbine blade is modified. First, according to the method of parameterization, the offshore wind turbine model is established, and a series of characteristics of the offshore wind turbine are obtained. Second, we add flaps with different lengths to the trailing edge of NACA0021 airfoil to obtain different dynamic characteristics. The angle of the additional trailing edge flaps is modified. Finally, a simulation model for the modified airfoil of the vertical axis offshore wind turbine is reestablished, and the variable characteristics of the performance is studied. Through the optimization and analysis of the blade structure, this study has obtained the best parameters of the length and angle of the offshore wind turbine blade trailing edge flap. The optimization of the blade structure changes the flow field around the blade, which significantly improves the maximum wind energy capture rate and self-starting ability of the vertical axis offshore wind turbine.