Research On Pitch Law Of H-type Vertical Axis Wind Turbine

In recent years,energy and environmental problems have become prominent.As a crucial component of energy development strategy,wind energy has attracted widespread attention.Currently,wind turbines are mainly divided into horizontal axis wind turbines and vertical axis wind turbines.Compared with horizontal axis wind turbines,vertical axis wind turbines have advantages of non-yaw,low noise,convenient for installation and maintenance and easy for airfoil manufacturing.Therefore,vertical axis wind turbines have become the focus of attention.In various vertical axis wind turbine types,the H-type vertical axis wind turbine(H-type VAWT)is widespread used.But there are still some problems such as its low power coefficient and so poor self-starting performance that impede its development.This paper aims to improve the wind energy utilization of the H-type VAWT,and studies the improvement of wind energy utilization and self-starting performance of the H-type VAWT through pitch.Firstly,the basic parameters and theories of the H-type VAWT are analyzed,and the existing mathematical model of the vertical axis VAWT is studied,the advantages of different models are compared.Based on NACA0012 airfoil,the change of attack angle and blade pitch angle in different operation hours are obtained.Based on the theories of variable pitch angle,ideal variable pitch curve was analyzed.Secondly,using double-multiple streamtube model established the mathematical model of the H-type VAWT.The more accurate multi-tube model pitching was obtained.According to the actual operation of the H-type VAWT,the model is optimized,and a minimum sine curve correction algorithm is proposed.After the optimized variable pitch curves of the streamtube model,the applicable variable pitch law can be summed up.Through analysis and comparison,it was shown that the pitch law has a significant effect on the performance of the H-type VAWT.Then,in order to further study the practical pitching law,a preliminary two-dimensional model of the H-type VAWT blade was established.The computational fluid dynamics(CFD)was used to simulate the wind conditions of the blade.The aerodynamic cloud diagrams of the blade at different states were obtained and the aerodynamic cloud diagram was analyzed.The results show that the existence of blade wakes will have some impact on each other.A preliminary mathematical modeling of the effect of the wake on the blade was performed to analyze the wake effect,The wake effect was analyzed to reveal the effect of blade wake effects on pitch law.Influencing characteristics,a correction method for pitch law was proposed.Finally,combined with the pitch law studied in this paper,a wireless pitch control system of the H-type VAWT is proposed,and an experimental prototype is set up to carry out experiments.It is verified that the pitch control system has improved the performance of the H-type VAWT.