| The status of energy in national security and development has been increasing,traditional thermal power generation can not meet the current requirements for environmental protection,wind power generation as a renewable green energy technology has been rapidly developed.Wind turbine is a kind of tall and soft special structure,which is sensitive to the action of wind.As the core component of wind turbine,wind turbine blades bear the aerodynamic force that is transferred to the wheel hub of wind turbine along the blade.Therefore,it is necessary to study the wind load characteristics of wind turbine wheel hub.This article simulates the A and B landforms in the atmospheric boundary layer wind tunnel,and conducts the high-frequence force balance(HFFB)wind tunnel test for the horizontal axis wind turbine model.The effects of the blade pitch angle,wind direction angle,rotation speed of wind wheel and landscape category on wind load characteristics at the hub of horizontal axis wind turbine were studied.The main content of this article includes two aspects:1)Wind load characteristics at the hub of stationary state of horizontal axis wind turbine were studied;2)Wind load characteristics at the hub of rotational state of horizontal axis wind turbine were studied: the rotating state is divided into constant speed and variable speed.the influence of the blade pitch Angle,wind direction angle,rotation speed of wind wheel and landscape category on wind load characteristics of wind turbine hub was studied from the aspects of average wind force coefficient,pulsating wind force coefficient,power spectrum and coherence.The main conclusions are as follows: 1)Static state: the y axial average wind force coefficient is the largest at 0° wind angle and the smallest at 90° wind angle,The y axial average wind force coefficient corresponding to the 90° pitch angle is 33% of the 0° pitch angle;The y axial fluctuating wind force coefficient is the largest at 90° and 270° angle;the x axial average wind force coefficient is the largest at 90° wind angle and the smallest at 0°wind angle;The x axial average wind force coefficient corresponding to the 0° pitch angle is48% of the 90° pitch angle;The x axial fluctuating wind force coefficient is the largest at 0°and 180° angle;At 0° and 90° pitch angles,sharp spectral peaks caused by balance-model resonance appeared in both x and y axial fluctuating wind power spectrum at the reduced frequency of 0.6Hz;The coherence of along-across direction is very small,the coherence of90° pitch angle is slightly greater than 0° pitch angle.2)The frequency and damping of the balance-model system are identified,and the power spectrum is modified to eliminate the peak value caused by the balance-model resonance.3)Constant speed state: y axial average coefficient of wind direction at 0° angle is the largest,45° angle is minimal;The y axial fluctuating wind coefficient is the largest at 45° wind angle,and average and fluctuating wind force coefficient of 60° pitch angle is smaller than other pitch angle;x axial average coefficient of wind direction at 45° angle is the largest,0° angle is minimal;The x axialfluctuating wind coefficient is the largest at 0° wind angle,and average and fluctuating wind force coefficient of 60° pitch angle is greater than other pitch angle;Both x and y axial fluctuating wind power spectrum show spectral peaks caused by wind turbine rotation and balance-model resonance at reduction frequencies of 0.4Hz and 0.6Hz;The coherence of 0°pitch angle is greater than that of other pitch angles.4)Variable speed state: the axial average and fluctuating wind coefficient of x and y increase unevenly with the increase of rotation speed;The above two spectral peaks also exist in x and y axial fluctuating wind power spectrum,moreover,the rotation speed of the wind wheel has a greater influence on the x axial power spectrum energy;The coherence of along-across direction increases with the increase of rotating speed. |
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