Research On Rotor Configuration And Pitch Control Of H-darrieus Wind Turbine

The horizontal motion of atmosphere on the surface of the earth is called the wind,which is the result of comprehensive actions of the factors such as the earth’s rotation,radiation temperature of the sun and so on.The wind energy resource on the earth is abundant,and it has become the most widely used new energy resource in the industrial utilization,with a increasing strategic position in energy development.The vertical axis wind turbine is one kind of wind power equipment with great developing potentiality,especially for the straight-bladed vertical axis wind turbines(short for SB-VAWT,or H-Darrieus)which can be comparable with horizontal axis wind turbine.The H-Darrieus wind turbine gain increasing interest for its virtues,including the ability of collecting wind from any direction without yaw mechanism,simple manufacturing process,better supporting stiffness of blade,simple transmission and much lower center of gravity.However,the poor self-starting and relative low power coefficient of H-Darrieus restrict its large-scale development;meanwhile,the complication of the flow field made the aerodynamic force of the blade unsteadily and periodically,leading an absence of mechanical problems for H-Darrieus.Therefore,the investigations on the flow field of H-Darrieus,mechanism of aerodynamic loads and the rotor dynamic response have an important significance for aerodynamic structure design of the H-Darrieus wind turbine.The research problems are determined on the basis of compresion of H-Darrieus and HAWT.From the research on the improvement of aerodynamic performance of H-Darrieus,the aerodynamic structure optimization method of the rotor is established via the height-radius ratio,chord-radius ratio,blade number and operating tip speed ratios(TSRs);furthermore,an approach of controlling the blade pitch angle is proposed to improve self-starting capacity and power coefficient.The flow field characteristics and mechanical properties of H-Darrieus will be studied by using computational fluid dynamics(CFD)method and experimental verification,and the method for information collection and condition monitoring method is presented in this paper.Numerical simulations based on CFD is carried out to investigate the influences of rotor parameters on the performance criterions of the H-Darrieus.Taking the average power coefficient of H-Darrieus as research objects,a mechanical model considering the local flow field of blade is established,as well as its performance criterions.With a two dimensional CFD model be biult,the effects of CFD model and its parameters on the computational accuracy are analyzed,and a contrastive analysis is done between the computed result and experimental data.The airfoil of this paper is chose by CFD simulations,and investigations of height-radius ratio,chord-radius ratio,blade number and operating TSRs on rotor aerodynamic performance,achieving the rotor configuration.Investigations on structural configuration and aerodynamic shape design for supporting beams are carried out to obtain their influences on aerodynamic performance and structural dynamic characteristics of the H-Darrieus.Taking the lateral deformation of blade as the research object,with mechanical models under different support way be established,researches of supporting beams configuration on deformation and bending moment of blade are done,and the dynamic response of various supporting configuration are studied by using fluid-structure interaction method.What’s more,the lift and resistance characteristics of aerodynamic configuration of several supporting beams are conducted and obtain a better contour for the supporting beams,by using the CFD and experiment methods,and a drag reduction method is analyzed.Investigations on the problems of dynamic stiffening and dynamic balancing of the rotor are performed.The deformation equations of supporting beam under the condition of aerodynamic force and rotating speed are built,which lay the theoretical foundation for the deformation analysis and correction of the rotor;furthermore,a soft cable preloaded method is put forward to improve the deflection of the wind turbine.With the rotor configuration optimization implemented,studies of angle of attack and blade pitch angle on the aerodynamic parameters and operating performance of H-Darrieus wind turbine are carried out,laying a foundation for blade pitch control,and a condition monitoring system of H-Darrieus is put forward.The condition monitoring of aerodynamic loads and structural dynamic response is achieved by using strain gauges,and calibration experiments of the condition monitoring system are implemented by applying static load,achieving the preliminary basis for experimental researches.By using CFD method,a series of researches on variation of blade aerodynamic loads and mechanism of dynamic stall under sinusoidal pitching motion are done,and methods for measuring the aerodynamic loads and pitch moment of blade are present.Moreover,the influences of blade pitch angle on operating performance of the H-Darrieus are explored by using the CFD and experimental studies.Based on the present variable-pitch laws,CFD and experimental researches are carried out to verify the effectiveness of the present blade pitch method.The adaptability and power generation of NACA0018 under collective pitch control are conducted.From the comparative analysis of aerodynamic performance,mechanical parameters and flow field between the individual variable-pitch method and fixed blade pitch,further optimization is done and comes to the half-sine law.The feasibility experiments are performed from the aspects of power generation,structural response and power consumption.