树木气弹模型风致响应特性的风洞试验研究

Wind tunnel study on wind-induced response characteristics of an aeroelastic model tree

  • 摘要: 为研究风荷载作用下树木的风致位移响应特性,揭示不同尺度阵风与树木风致位移的相互关系,基于满足主要相似要求的树木缩尺气弹模型,参照工程科学数据集ESDU 85020,在风洞中构建相应风场,通过同步测量风速、树冠中心位移和树干位移,开展了树干-树冠-风速三者之间的相互关系和时频特征研究。结果表明:树冠中心位移、树干位移、风速三者之间呈正相关关系,三者之间的互功率谱密度函数解释了其时域和振型特征;树冠中心位移和树干位移均以顺风向为主;树叶数量增加到一定程度时可以减缓树冠中心位移,但是不能减缓树干位移;树冠中心和树干位移的脉动特性主要受树冠频率控制,树冠中心和树干的风致位移响应主要受大尺度阵风控制,满足准定常假设。

     

    Abstract: This study aims to investigate wind-induced displacement response characteristics of trees under wind load, analyze interactions and tempo-frequency characteristics, discover gust effects on canopy and trunk displacements with different crown configurations. Based on an aeroelastic model tree that meets major similarity requirements, wind tunnel terrain was constructed according to the engineering database of ESDU 85020, and the wind speed, crown center and trunk displacements were measured synchronously. The results show that the crown center and trunk displacements are mainly along the wind direction, and the crown center displacement, trunk displacement and wind speed exhibit positive correlation, and their co-spectral density functions elucidate their temporal characteristics and mode shape characteristics of the model. Leaf number that reaches a certain level can mitigate crown center displacement but has a limited impact on trunk displacement. The wind-induced displacements of crown center and trunk are dominated by large-scale gusts, which indicates that it meets the quasi-steady assumption.

     

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