风力机叶片挥舞摆振气弹失稳分析

为避免风机叶片在强风作用下发生破坏,需对其采取停机保护措施。该文研究叶片处于非旋转状态时的挥舞摆振气弹失稳现象发生的条件。基于风力机叶片简化模型,采用迭代法求解叶片的自振频率及振型,建立了非旋转叶片挥舞摆振气弹效应响应的振型叠加法,该方法可以便捷地进行叶片多工况气动弹性响应分析。计算了在不同风速不同攻角条件下叶片的挥舞摆振气弹效应响应,得到了叶片挥舞摆振响应随风速和风攻角的变化规律以及不稳定风攻角的分布特征。结果表明:在某些风攻角下,风机叶片挥舞摆振失稳现象在风速较低的情况就有可能发生,其响应幅值与结构阻尼联系紧密。另外,挥舞摆振失稳会大大增加作用于叶片上的风荷载,并进一步造成叶片结构的损伤破坏。

CALCULATING FOR AERODYNAMIC STABILITY RESPONSE OF WIND TURBINE BLADE IN FLAPWISE AND EDGEWISE DIRECTION

The measures of a force stoppage should be taken to avoid wind turbine blade damage under strong wind. The precondition for the flapwise and edgewise aeroelastic instability of a wind turbine blade on a non-rotating state was studied. Based on a simplified model, the natural frequency and vibration mode of a wind turbine blade were calculated by applying an iterative method. A modal superposition method was established, which could conveniently analyze the flapwise and edgewise vibration response of a wind turbine blade on a non-rotating state. The variation of flapwise and edgewise vibration response under different wind speed and attack angles and the distribution of a unstable wind attack angle were obtained. The results show that the response of the flapwise and edgewise vibration of a blade may be unstable even if wind speed is not too high in some attack angles, and it has great relationship with the inherent damping ratio of blades. Moreover, flapwise and edgewise instability will increase the wind load acting on blades significantly, and this kind of accretion may lead to failure of a wind turbine blade severely.