大型水平轴风力发电机桨叶稳定性研究

大型水平轴风力发电机桨叶为流-刚-柔耦合的周期时变多体系统。本文暂未考虑风载荷,分析了重力载荷和桨叶预锥角、转速等因素的变化对稳定性的影响。力学建模中,考虑了桨叶挥舞、摆振、扭转和轴向运动以及根部铰的挥舞、摆振和变矩等刚体运动。利用有限元法形成5节点18自由度的刚-柔混合梁单元模型,应用Hamilton原理建立桨叶动力学方程,求得对应的摄动方程,采用Newmark隐式积分方法求解。根据Floquet理论判断运动稳定性,计算了相关转换矩阵的特征值。结果表明预锥角对桨叶运动稳定性影响不容忽视。在通常的工况下,桨叶能够稳定地运转。

STABILITY OF A HORIZONTAL AXIS WIND TURBINE BLADE

The blade of a large horizontal axis wind turbine is a nonlinear periodic multi-body system with fluid-rigid-flexible coupling. The blade motion stability involves the effects of gravity, the blades pre-cone and the rotating speed. The blade has elastic flap-lag-torsion and axial deflections along with rigid displacements of the flap, lag and pitch hinges. A new 5 node 18 DOF rigid-elastic beam element with three rigid displacements and fifteen nodal displacements is used to model the blade. The dynamics equations are derived using the Hamilton principle. The perturbation equations are then derived and solved using the Newmark integration method. The Floquet theory is used to analyze the blade stability by calculating the eigenvalues of the transition matrix. The results show that the effects of the blades pre-cone on the motion stability cannot be neglected without wind load and the isolated blade is stable when the turbine has a normal angular speed.