Dynamic Load CharacteristicsResearch For Rotor System Of Horizontal Axis Wind Turbine

Rotor system is one of the most inportant parts of wind turbine, the research about its dynamic load characteristics and aeroelastic coupling characteristics during wind turbine nomal operation is the important theory basic of wind turbine design and optimization, and ensuring operating life and security and stability of whole wind turbine.Based on the reduced version of Beddoes-Leishman model, dynamic stall charactrestic of NACA0012airfoil is simulated and analysised through using self-written Matlab program. The simulated result shows when variable range of angle of attack locates in the static stall range of airfoil, dynamic stall angle of attack is delayed, compared with static aerodynamic coefficient, dynamic lift coefficient is increased obviously,but the change of dynamic drag coefficient is very little.The effect of model parameters to airfoil dynamic stall is researched, the result shows when angle of attack locates in the range of light stall and deep stall, the effect of dynamic stall is obvious. Flow separation of airfoil is restrained with reduced frequence increasing.The max lift coefficient is increased through increasing the pressure constant, while the dynamic stall angle of attack is increased through increasing the boundary lag time constant.On the basic of classical Blade Element Momentum (BEM) theory and related corrections, dynamic inflow models of Pitt-Pitters and TUDkare introduced in the classical BEM respectively. Load calculationMatlab program ofrigid rotor system based on above two modelsiswritten and debugged separately.The result of gust wind condition shows the calculated resultof TUDk model is basically consistent with GL GH Bladed resultin induced speed and rotor loads, so the validity of Matlab programcalculatedresult is verified. The result of dynamic pitching condition shows Pitt-Pitters model and TUDk model can reflect load impact phenomenonof rotor system compared with equilibrium wake model, in which dynamic inflow effect is not considered. On the basic of dynamic inflow model, dynamic stall model isintroduced into time domain simulation of rotor system load. Dynamic load characteristics of rotor system are analysised under turbulent wind condition, the result shows both of blade element load and whole rotor system load are increased obviously compared with the result which is not considering the dynamic stall effect.Baded on dynamic deformation theory of beam, structure dynamic equations of blade for considering and notconsidering about centrifugal stiffening effect are established respectively.The calculated method ofaerodynamic damping on blade elment areresearched and deduced, the Matlab simulated program for aerodynamic damping is established, and the simulated result shows negative damping occurs more easily in edgewise than flapwise of blade element. Mode superposition method is combined with BEM,Matlab calculated program of rotor system load considering aeroelastic coupling is established.Blade modal aeroelastic dampingcharacteristic responsing to pitch angle is simulated and researched, the result shows blade used in this paper is stable inaeroelastic.Under turbulent wind condition,the silumated results keep consistent with the caculated result of GL GH Bladed in rotor system load and flexible deformation, the reasonableness of calculated resultsof Matlab program is demonstrated.