行道树风致响应的风洞试验研究

Wind tunnel test on wind-induced responses of roadside trees

本文主要研究树木在一定风速下的树木变形及受力状况。使用photoshop软件算出树木的迎风面积和疏透度,得到了树木迎风面积和疏透度分别与风速的关系。结果表明在风速增加时模型树在四个风向角下其迎风面积都呈减小趋势,但其疏透度呈增加态势。运用六分力天平测力技术测得树木在一定风速下阻力,得出模型树阻力是随着风速的增加而呈幂函数关系增加的。同时探讨了模型树在特定风速下的阻力系数的变化情况,结果表明模型树在迎面面积减小、疏透度增加的情况下其阻力系数随着风速增加而呈幂函数下降。这说明树木的流线缩减效应减小了风荷载的进一步增加,进而利用本身的柔韧性保护自身安全,促使其自身在高风速下受到的阻力相对减小。

This paper mainly studies the reconfiguration and force condition of trees under certain wind speeds. With Photoshop used to calculate the frontal area and the porosity, the relationship between the frontal area and the porosity and the wind speed were obtained.The results suggest that the frontal area of the model tree decreases at four wind direction angles,but its porosity increases.The drag of the trees at a certain wind speed is measured by the six-component balance force measurement technique.The conclusion that the drag of the model tree increases in power function with the increase of the wind speed was reached.In the mean time, we studied the variation of the drag coefficient of the model tree at a specific wind speed.The results show that the drag coefficient decreases in power function with the increase of wind speed.This shows that the streamline reconfiguration effect of the tree reduces the further increase of the wind load, and then uses its own flexibility to protect itself and reduce its own drag at the high wind speed.