Research And Development Of High Efficiency Lift-drag Composite Vertical Axis Wind Wheel Based On Technology Of Energy Harvest

With the deepening of China’s green development strategy,the vertical axis wind turbine,one of the main ways to utilize wind energy,has fallen into a development bottleneck due to its low efficiency.The improvement of efficiency is difficult to be realized by simply relying on the traditional structure optimization.However,advances in piezoelectric materials and electronic technology bring new solutions to this problem.In wind turbines for structure optimization on the basis of introducing the energy harvest cantilever structure,the vibration and structural deformation in the process of dissipation of energy into electricity,can further enhance the overall efficiency of the wind turbine,make up for the structural optimization of wind energy utilization rate of ascension limitations,it is of great significance to the development of vertical axis wind turbine.Guided by the piezoelectric energy harvest technology,this paper studies the influence of various size parameters on the aerodynamic,structural and piezoelectric performance of the wind wheel by combining the structure of the vertical axial wind wheel with the combination of lift-resistance and the analysis methods of fluid-solid coupling and piezoelectric coupling.The response surface method is used to optimize the structure design.The simulation results and experimental results are analyzed to verify the efficiency of the new type of vertical axis wind wheel with lift-resistance energy harvester.The main research contents are as follows:Firstly,by systematically analyzing the realization forms,structural characteristics and operation state of various energy harvest technologies,the resistance type piezoelectric energy harvesting cantilever is determined as the supplementary path for wind power conversion of wind turbine.Based on the traditional lift type wind wheel the cantilever motion equation and the equivalent dynamics model of the wind wheel are established.The influence of structural parameters such as cantilever section shape,length,width and thickness on aerodynamic performance,structural performance and natural frequency of the wind wheel is determined.Based on ANSYS Design Exploration,the cantilever of lift type wind wheel was optimized,and the maximum stress,maximum strain and torque of parabolic section cantilever H type wind wheel were reduced by 8.6%,9.4% and 13.82%respectively.Secondly,the influence of wind resistance structure and size parameters on the aerodynamic and structural performance of the wind wheel is analyzed.Combined with the optimized basic size of the lift type wind wheel,the model of the vertical axis wind wheel with liftresistance composite was established,and the fluid-solid coupling analysis,mechanical characteristics analysis and modal analysis under preloading were carried out.The results show that the performance of the new wind wheel is excellent,which can effectively improve the output torque of the wind wheel,up to 22.9%,while providing the deformation required for energy capture.Then,the dynamic model and electromechanical coupling model of energy capture cantilever are established,and the factors affecting the efficiency of the cantilever energy harvester system are analyzed.The results of piezoelectric coupling analysis show that the maximum output voltage of the optimized resistance type energy harvesting cantilever can reach 99.734 V.Finally,through the vibration condition monitoring of the optimized prototype of the wind wheel,it is concluded that the first-order natural frequency of the wind wheel is 8.2493 Hz,which is close to the value of the first wave peak frequency(7.5Hz)in the actual operating state,and the maximum frequency of the optimized design of the lift-resistance complementary wind wheel is 6.9275 Hz,which has better safety and stability.The experimental results of cantilever energy capture efficiency verification show that the average output voltage of the cantilever can reach 89.288 v.Although the output result is slightly less than the theoretical value due to the objective experimental conditions,it still has a considerable energy conversion rate and output efficiency.