Research On Key Technology Of Wind-collected Horizontal Axis Wind Turbines

The growing depletion of traditional energy and the high attention on the environmental issues have prompted countries to focus more on the development and use of renewable energy sources,especially,the application of wind power generation is more and more widely all over the world.Generally,the starting threshold of wind velocity of current horizontal axis wind turbine is about 3.0~3.5 m/s,rated wind speed is above 10m/s.When the wind speed is too high,the wind turbine is often in a state of less than full load during operation,which reduces the power generation and makes the rating power of existing wind turbine very large but the annual average power generation very low.The waste of wind energy resources is severe.In view of the above problems,in order to solve the problems of low starting threshold of wind velocity of horizontal axis wind turbine and increase the output power of single machine,a kind of wind-collected horizontal axis wind turbine is proposed in this paper.This kind of wind turbines can guide the flow by using the variable cross-section channel of the wind concentrator,which reduces the flow loss at the tip of the blades and significantly increases the wind speed acting on the blades.At the same time,the wind speed of the wind turbine is reduced by using 5-blade-form,and the static starting characteristic and dynamic output performance of the wind turbine are improved as a whole.This paper works on the optimal design of the structure parameters of the wind concentrator,the design of blade aerodynamic shape,the calculation of starting performance and the research on simulation analysis of whole machine’s performance,etc.,with the help of numerical simulation,based on the analysis of the control equations of fluid mechanics and the basic aerodynamic theory of the aerodynamic shape design of the blade.This paper selects the form of the accelerator tube used in the wind concentrator,and confirms that the main structural parameters which affect the wind speed amplification performance of the wind concentrator are the shrinkage angle α and the characteristic length L.On the basis of that,this paper carries out simulation experimental design of 25 sample points,and 25 sample data were calculated by means of numerical simulation,including the average wind speed of the outlet,the average static pressure of inlet/outlet and the average dynamic pressure of inlet/outlet.The response surface model is used to predict the response of unknown points when α=20~45° and L=0.5~3.5m,and the three-dimensional response surface of the average export wind speed is established to analyze the influence of shrinkage angle α and the length L on the air velocity and pressure in the wind concentrator.The optimal solution of the average export wind speed,the shrinkage angle and the characteristic length of the wind concentrator are calculated and verified by the quadratic sequence programming method in the Matlab optimization toolbox.In the design of blade aerodynamic shape,the airfoil of blade is selected,and the overall design parameters of the blade are determined in this paper.The impeller diameter,axial/tangential induction factor,tip speed ratio,installation angle,chord length and other airfoil geometry parameters are determined according to Glauert design method.This paper uses the spatial coordinate transformation to solve the three-dimensional actual spatial coordinates of each blade discrete points,draw the cross-section of each blade,and establishes the three-dimensional model of the blades by using UG software.In addition,using ANSYS Workbench software,the blade modal analysis is carried out,and the natural frequency of the blade and vibration mode is obtained.In this paper,the starting torque and starting threshold of wind velocity of the impeller are calculated according to the aerodynamic load calculation method.The flow field characteristics of wind-collected wind turbine-generator are simulated by using Fluent software,including the wind speed which has actual effect on the blade,the pressure on windward and leeward of the blade,and the wind speed amplification performance.Finally,the wind speed magnification and the starting threshold of wind velocity of wind-collected wind turbine-generator are determined.