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標題: 大氣邊界層流場部分模擬及氣動力實驗應用
Part-depth Simulation of Atmospheric Boundary Layers and Its Applications in Wind Tunnel Tests
作者: 孫德偉
Sun, Te-Wei
關鍵字: wind tunnel test;風洞實驗;part-depth simulation;scale factor;low-rise buildings;部分模擬;尺度因子;低層建築物
出版社: 土木工程學系
範圍。研究顯示,渦流產生器的下底寬度影響積分長度尺度 的大小,上底寬度與渦流產生器高度影響部分模擬的有效高度。粗糙元素的疏密間隔可有效調整所需紊流強度。風壓機率密度函數型態在TTU模型的驗證中,屋頂角落附近,平均風壓係數的機率密度函數在各風攻角大於高斯分佈,呈現右偏。牆面中央在迎風面的機率密度函數大於高斯分佈,呈現左偏。模型牆面由側風面到背風面,機率密度函數略大於高斯分佈。屋頂中央各種風攻角下,平均風壓係數機率密度函數大於高斯分佈。經與TTU實場量測成果相比較,證明採用部分模擬之大氣邊界層流場,對低層建築物之氣動力實驗,較直接模擬流場特徵值的均勻紊流場氣動力實驗,有更佳的效果。尖峰風壓分佈中低層建築物表面風壓大多不屬於高斯分佈的型態,而且PDF型態多呈現高狹峰。利用Type I極值分佈推估其尖峰風壓的準確性顯然高於以高斯模式推估的結果。

A part-depth simulation of atmospheric boundary layer which is based on full-depth simulation techniques developed by Counihan and Standen is conducted in this study. The vortex-generator and roughness elements are used in this study to simulate atmospheric boundary layer in wind tunnel. The mean velocity profile, turbulence intensity, power spectra, and integral length scale of flow field are checked. The results shown that the properties of the simulated flow field are accepted and suitable to be used in the aerodynamic tests. Also we found that the scale factor of flow field could be another important reference in wind tunnel tests besides boundary layer thickness.
The part-depth simulated flow field was used to check the pressure distribution on the roof of scaled down low-rise building model used by TTU real field test. The measured pressure distribution are compared to the TTU results and shown they were similar. In this study we found that the size of vortex-generator is related to the integral length scale and effect height of the boundary flow field. The probability distribution function of the roof corner, front face, side face and rear face of the model are also investigated with different angles of approaching flow. The probability distribution of peak pressures on roof are almost identical to the Type I extreme value distribution. This study shown that the aerodynamic experiments results got in part-depth simulated atmospheric boundary layer is similar to the results in the full-depth simulated atmospheric boundary layer in larger wind tunnel for the tests of low-rise buildings, but the technique developed in this study will be much more economical.
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