Study Of Aerodynamic Characteristic And Flow Filed Of Coaxial Counter-Rotating Verticalaxis Wind Turbine Blade

With the global emphasis on environmental protection and carbon emissions in the 21 st century,the main direction of development research in nations has turned to enhancing energy utilization and exploiting new energy sources.Wind and solar energy have been researched for centuries as a huge energy treasure that can be produced continuously.Among them,vertical axis wind turbine(VAWT)have received a lot of attention from researchers because of their unique advantages.This paper designs a new type of vertical axis wind turbine with coaxial counter-rotating vertical axis wind turbine blade(CR-VAWT)on the basis of VAWT and compares the lift and drag coefficients of CR-VAWT and common VAWT.The studies indicate that the peak of torque coefficient of CR-VAWT with the same parameters is higher than the peak of VAWT by 2.54%,and the structure of CR-VAWT can be installed in a wind farm to augment the generation efficiency.In order to study the development of internal vortex of CR-VAWT in depth,we firstly compare the torque coefficient,vortex volume and turbulence energy variation within the spacing for CR-VAWT at 10 mm and 30 mm spacing,and the results show that the total average power coefficient of upper and lower wind turbine at 10 mm spacing is about 1.24% higher than the average power coefficient at 30 mm spacing.For the comparison of the pressure distribution around the blade under different working conditions,the pressure distribution of the suction surface and pressure surface at the leading edge and trailing edge of the blade are very different in size,and the pressure coefficient of the blade near the wind turbine pitch is higher.Spacing 10 mm blade leading edge pressure coefficient curve fluctuations than the spacing 30 mm blade trailing edge curve fluctuations.Secondly,in the study of the tip speed ratio for aerodynamic performance,tip speed ratio 1.2 of the upper and lower wind turbine average power coefficient is also higher than the tip speed ratio 1.8 average power coefficient.The leading edge around the blade with lower tip speed ratio has higher pressure distribution,especially the pressure distribution at the leading edge of the blade at the pitch of the coaxial reversing upper and lower wind turbine reaches the highest.Finally,for the tail flow development of CR-VAWT under different operating conditions,the velocity trailing development at the trailing direction of the upper and lower wind turbine is different,and the recovery degree of velocity loss of 10 mm spacing is smaller than that of 30 mm spacing.The wind turbine with tip speed ratio 1.2 has more intense distribution of leaf tip vortex and shedding vortex around the wind turbine,and the peak value of turbulent kinetic energy and pressure coefficient fluctuation in the wind turbine spacing is higher than the peak value of tip speed ratio 1.8 when the upper and lower wind turbines meet,and the wake development of tip speed ratio 1.2 decays more slowly than that of tip speed ratio 1.8.