Study On Aerodynamic Performance Of Floating Φ-type Vertical Axis Wind Turbine

Vertical axis wind turbines have the advantages of receiving universal wind directions,low maintenance cost,and low aerodynamic noise.However,due to the problems of poor startup performance and low wind energy utilization,their application in practical engineering has been restricted.By transferring the vertical axis wind turbine to work in the offshore wind environment and selecting the Φ-type as the structural form of the wind turbine,the problems of poor startup performance and low wind energy utilization might be effectively alleviated.However,the aerodynamic performance of floating Φ-type vertical axis wind turbines are very complicated,thus the research on the aerodynamic performance of floating Φ-type vertical axis wind turbines has very important value and significance.In this paper,the CFD method is employed to study the aerodynamic performance of a floating Φ-type vertical axis wind turbine,and the simulation results of the wind energy utilization rate obtained by the IDDES SST k-ω turbulence model are compared with experimental values for verification purpose.The results show that the IDDES SST k-ω model is more accurate in simulating the wind energy utilization coefficient of theΦ-type vertical axis wind turbine,and the wind energy utilization rate gradually increases with the increase of the tip speed ratio λ.Because of the small tangential velocity,the end section of Φ-type blade is prone to have dynamic stall effect.Also,the vorticity in the flow field region varies with different positions.The effects of surge motion of platform on the wind turbine are studied,and the laws of characteristics of the flow field are summarized.In addition,the parameters of the aerodynamic performance under different surge amplitudes and periods are compared.The results show that the surge motion enlarges the difference of torque and pressure while the structural load and fatigue are increased.With the increase of the amplitude and the decrease of the period,the surge motion becomes intense,and the mutual interference between the blade and the airflow also increases,which is not conducive to the safety and stability of the structure.The differences and connections between pitch motion and surge motion of platform are studied.The analysis focuses on the changes of pressure coefficients and details of flow fields at different height sections under pitch.The results show that the effects of surge-like motion and surge motion on the aerodynamic performance of the wind turbine are similar.The pressure coefficients of the upper,middle and lower cross sections of the blades under the pitching motion are quite different,and the speed of energy dissipation is slower than the surge motion.The effect of reducing the aerodynamic performance parameters of wind turbines in pitch motion is obvious.The research results in this paper provide important reference for the layout optimization of offshore wind farms,the maintenance and reinforcement of existing offshore wind turbines,and the design and selection of new offshore wind turbines,which will help promote the future optimization and application of vertical axis wind turbines.