大氣邊界層特性之實場監測及風洞實驗模擬

Field measurements and wind tunnel investigation on the characteristics of atmospheric boundary layer

曾鈺婷(Yu-ting Tzeng)

指導教授 ： 鄭啟明

淡江大學/工學院/土木工程學系碩士班/碩士(2011年)

https://doi.org/10.6846/TKU.2011.00343

摘要

隨著人口膨脹迅速，在有限的土地上為求生活空間，建築物只有往上發展，因此現代都市中越來越多高層建築物。然而高層建築的設計發展方向朝向高度高和輕質量，為因應對風的敏感程度增加，在亞熱帶島嶼的台灣，冬天有東北季風，夏天又常有颱風侵襲，由於高層建築相對於低矮建築來說勁度較低，且當建築物愈接近地面因地表粗糙度的關係風力較小，因此愈高的建築物所受到的風力會愈大，因此風力對於結構物的反應成為高層建築設計裡重要的一環。
本研究對台北市中心與淡水濱海地區兩個地方做邊界層特性的實場監測，取得颱風與東北季風的實測數據。並進行實際地況模型和粗糙元素的風洞模擬實驗，驗證實場監測得到結果。本文探討的邊界層特性包含風速剖面、紊流特性、陣風因子、空間相關性等重要風場特性。
研究結果顯示：在強風下，平均風速強度對風速剖面指數值有些許的影響，紊流強度隨著平均風速強度增加而遞減，而順風向積分尺度長度則隨著平均風速強度增加而遞增，Von-Karman 經驗頻譜公式作為代表該地自然風場特性的建議參數值，不同高度的空間相關性符合Davenport建議參數值。無論是實際地況模型或是粗糙元素的風洞模擬實驗，在精密縮尺條件下，風場特性與實場監測結果做比較，都有不錯的相似性。

關鍵字

自然風場 ； 實場監測 ； 粗糙元素

並列摘要

The population is growing rapidly in Taiwan, and as a result the geographical area encapsulating the population is decreasing dramatically. This is forcing people to use space more efficiently, and this was reflected by constructing tall, multi-storey buildings. Therefore, it is often common to see a lot of tall buildings in modern and congested cities. However, according to reinforcing of wind, tall buildings are of exceptional height and relatively low mass. These two characteristics have their advantages and disadvantages.
Since Taiwan is located in the subtropical zone, it has northeast monsoon in the winter and typhoons in the summer, so people have to be extremely considerate when it comes to designing tall buildings in such conditions. It is critically important that they understand the causes and effects of wind power on the buildings’ physical structures. For example, tall constructions are stiffer than low ones; however they suffer more pressure from wind.
The main objective of this research is to discuss the different characteristics of atmospheric boundary layer between Taipei city and Danshui. It also focuses on the comparison between the wind tunnel experiments and field measurement. It includes characteristics of atmospheric boundary layer, wind profile, turbulence intensity, turbulence length scale, turbulence spectrum, gust factor, and coherence function.
According to the experiment result, it shows that the average intensity of wind velocity have some effects on the wind profile figure under a strong wind circumstance; the turbulence intensity decrease steadily when there is an increase on the average intensity of wind velocity. On the other hand, the turbulence length scale expands while the average intensity of wind velocity increases. The Von-Karman spectrum density function represent the recommended figure of local’s normal wind characteristics. Different level of height of Coherence Function satisfied Davenport’s recommended figure. Under the accurate reduced scale conditions, both the Practical situation model and wind tunnel investigation have similar outcome after comparing the result of the Characteristics of wind field and Field measurement.

並列關鍵字

natural wind characteristics ； field measurement ； Roughness element

參考文獻

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