风机叶片疲劳加载振动频率特性分析与试验

针对风机叶片疲劳加载过程振动特性,建立旋转偏心块驱动的叶片疲劳加载系统动力学模型。基于拉格朗日方程推导出系统的数学模型,利用平均法近似解析系统动力学方程,得出振动过程中电机转矩平衡方程。分析振动频率的变化规律,建立仿真模型,对系统频率捕获过程进行数值仿真,揭示系统的自同步振动特性。风机叶片疲劳加载试验表明:叶片在受迫振动时,叶片振动频率并不总等于驱动频率;驱动频率与叶片固有频率偏差较大时,叶片振动幅值及频率波动明显;频率偏差在较小区间范围(0.47~0.62Hz)时,偏心块驱动系统与叶片容易发生频率捕获,振幅较小并趋于稳定;在负载转矩较大而电机功率不足时,偏心块会发生转速跳变。

Analysis on Coupling Vibration Frequency Characteristics of Wind Turbine Blade Rotating Fatigue Loading System

In light of the characteristics of coupling vibration in the wind blade fatigue loading process, a dynamic blade fatigue loading system model block driven by a rotating eccentric was established. An electromechanical coupling mathematic model was derived using the Lagrange equation. The system dynamics equations were approximate analysis by using the averaging method, then the torque balance equation of vibration was obtained. Based on analysis of the variation in vibration frequency, the simulation model was established. Numerical simulations on the system frequency capture process, and revealed the characteristics of a self synchronous vibration system. Finally, the correctness of the mathematical model and simulation results was verified by the wind blade fatigue loading. The results showed that the blade frequency and vibration amplitude fluctuation when the deviation between the driving and natural frequencies of the blades was obviously large. The frequency deviation in a small range (0.47~0.62 Hz), eccentric rotary system and blade will appear in frequency capture, and then amplitude tended to be stable, but decreased. When the load torque was larger and the motor power was insufficient, the eccentric block will rotate speed jump.