Aerodynamic Parameters of Regular Arrays of Rectangular Blocks with Various Geometries
Aerodynamic Parameters of Regular Arrays of Rectangular Blocks with Various Geometries
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DOI：
10.1007/s10546-009-9403-5
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发表时间：
2009-06
影响因子：
4.3
通讯作者：
A. Hagishima;J. Tanimoto;Koji Nagayama;Sho Meno
中科院分区：
文献类型：
--
作者：
A. Hagishima;J. Tanimoto;Koji Nagayama;Sho Meno
通过风洞试验研究了城市天线阵不同布局的气动力效应。分析中使用了三个表征阵列的空气动力学参数--阻力系数（Cd）、粗糙长度（Zo）和位移高度（d），其中Cd是基于使用浮动单元直接测量的总表面切变，而另外两个参数是通过对测量的风廓线和预定的总阻力进行对数拟合来估计的。设计了用于测量的63个阵列的配置，以估计布局、风向和块体高度变化对这些参数的影响。结果表明：（1）交错排列的Cd和z 0对平面面积指数（λp）和正面面积指数（λf）的响应最大，而正方形排列的Cd和z 0对λ p和λf的响应较弱。此外，风向为45°的正方形阵列具有相当大的Cd，并且风向增加了2倍。(2)当λ f超过20%时，粗糙度高度不均匀性对粗糙度的影响更加显著，且差异性特别显著，超过200%。(3)高块体布局对C_（max）的影响大于短块体布局。结果表明，风向和建筑物高度不均匀性对城市空气动力学参数的影响随λ p和λf的变化规律很大，应在考虑粗糙堆积密度时考虑这些影响。
The aerodynamic effects of various configurations of an urban array were investigated in a wind-tunnel experiment. Three aerodynamic parameters characterising arrays—the drag coefficient (Cd), roughness length (zo) and displacement height (d)—are used for analysis.Cdis based on the direct measurement of the total surface shear using a floating element, and the other two parameters are estimated by logarithmic fitting of the measured wind profile and predetermined total drag force. The configurations of 63 arrays used for measurement were designed to estimate the effects of layout, wind direction and the height variability of the blocks on these parameters for various roughness packing densities. The results are summarised as follows: (1) The estimatedCdandzoof the staggered arrays peak against the plan area index (λp) and frontal area index (λf), in contrast with values for the square arrays, which are less sensitive to λpand λf. In addition, the square arrays with a wind direction of 45° have a considerably largerCd, and the wind direction increaseszo/Hby up to a factor of 2. (2) The effect of the non-uniformity of roughness height onzois more remarkable when λfexceeds 20%, and the discrepancy inzois particularly remarkable and exceeds 200%. (3) The effect of the layout of tall blocks onCdis stronger than that of short blocks. These results indicate that the effects of both wind direction and the non-uniformity of the heights of buildings on urban aerodynamic parameters vary greatly with λpand λf; hence, these effects should be taken into account by considering the roughness packing density.