杨树叶风振实验研究

Experimental investigation on the deformation and vibration of a poplar leaf in wind

通过研究杨树叶及其模型在不同风速下的风振变形情况,发现基于风速和叶片长度的雷诺数是单一叶片振动变形的重要气动参数.实验主要采用摄像机记录树叶变形振动过程和粒子图像测速仪测量叶片尾流流场的方法进行.实验过程中,随着风速由小变大,真实树叶依次经过了静态变形,大幅低频振荡,叶片翻卷并重归静态,由静态变为大幅高频振动等不同状态.实验表明,随着风速的增大,人造树叶经历了与真实树叶相似的状态变化过程,但各个状态的临界雷诺数与真实树叶有所不同.

The deformation and vibration of a twig-connected single poplar leaf and its model in wind was investigated experimentally. Results showed that the Reynolds number based on wind speed and the length of leaf blade was a key parameter to the aerodynamic problem. The deformation and vibration of the leaf was recorded with a CCD camera, and the flow field downstream of the leaf was measured with PIV. With the increase of wind speed, the following deformation of the leaf was observed： static deformation, large amplitude and low frequency sway, turning upward and reconfiguration to static, and then large amplitude and high frequency vibration. The aerodynamic characteristics of an artificial poplar leaf made with PVC sheet were also investigated. The results show that, with the increase of wind speed, the artificial leaf experiences the same changes of deformation and vibration as those of the real leaf. But the critical Reynolds numbers of the artificial leaf are different from those of the real leaf.