建筑群不均匀性参数化方案的风洞实验

Wind tunnel experiments of parameters scheme of non-uniformity buildings

为了在参数化数值模型中更好地引入城市下垫面不均匀建筑群对大气动力特性的影响,从建筑几何结构的形态学角度出发,建立了描述城市建筑群不均匀性的形态学参数化方法,形成一组可以较为系统地表达建筑不均匀性的参数,包括迎风面积指数(λf)、平面面积指数(λp)、形状指数(SBC)和综合非直线系数(R).利用风洞实验方法研究建筑群各形态学参数对拖曳力的影响,其中整个区域所受的拖曳力采用悬浮实验平台直接测量.结果表明:周围环境地貌粗糙度的改变对拖曳力系数影响不明显;迎风面积指数是风向变化引起拖曳力系数变化的主要作用因素.实验工况之间对比表明,在迎风面积指数、平面面积指数、形状指数分别增大或综合非直线系数减小的单因素变化情况下拖曳力系数会出现不同程度地增大.

To more precisely describe the effects of non-uniform buildings on atmospheric dynamics in parametric numerical models,this paper set up a morphological parameterization method to represent the non-uniformity of buildings according to the geometric morphology of buildings,including the frontal area index（λf）,the plan area index（λp）,the shape index（SBC）,and the integrated non-linear coefficient（R）.Wind tunnel experiments were carried out to study the effect of buildings morphologic parameters on drag force.A floating experimental platform was designed to measure the drag force of the whole area.Results show that,different roughness of surrounding landforms has little effect on the drag coefficient,the frontal area index is the main factor of wind direction on the drag coefficient.The drag coefficient increases with the increasing of frontal area index,density index,shape index and the decreasing of integrated non-linear coefficient,respectively.