臺灣博碩士論文加值系統

本研究主要是探討都市地形下，兩排建築物形成之街谷對街谷內之汙染排放擴散之影響。利用大氣環境風洞配合適當的粗糙元素及渦流產生器，可模擬出所需之都市地形中性大氣紊流邊界層，該邊界層流之指數律風速剖面之n值為0.27，紊流強度為0.2~0.24間，均符合Counihan(1975)[6]實場研究結果之建議值。
在都市地形之中性大氣紊流邊界層下，研究探討兩排不同高度之建築物、街谷寬度以及不同之排放源高度等因素對於汙染物擴散特性之影響。實驗分析獲致以下結論：
(1) 當街谷寬度S變為狹窄時，廢氣污染濃度較易累積在街谷且較不易擴散，而各斷面垂直向最大濃度值在X/H=1.5時會有較大之下降幅度。若後排建築物高為2H時(此處H為前排建築物高度)，由於氣流通過前排建築物已產生分離現象，在極窄街谷寬度又碰上後排建築物產生分離現象，再加上受後排建築物之影響，使在後棟建築物迎風面產生明顯之下切氣流。
(2) 當兩排建築物間距變大時(亦即街谷寬度增加)，廢氣污染之濃度較易往下游擴散。而各斷面垂直向濃度最大值將沿下游緩慢下降，較不受兩排建築物高度差異之影響。
(3) 廢氣污染排放源高度，在相同街谷寬度以及前後排建築物高差條件下，對於廢氣污染濃度擴散特性無顯著地影響。
(4) 在各種狀況下廢氣污染團之垂直擴散尺度皆往下游漸增，但若遇到建築物後，垂直擴散尺度皆有突然下降之現象。
(5) 當前後排建築物高度固定，街谷寬度S變大，後排建築物表面濃度值皆明顯下降。當兩建築物等高，後排建築物迎風面濃度皆由下往上遞增；而當前後排建築物有明顯高差時，後排建築物迎風面濃度皆由下往上遞減。後排建築物頂面，無論前後排建築物等高或有高差，表面濃度大都由上游往下游遞減。

摘要 I
ABSTRACT II
目次 III
圖目次 V
表目次 IX
第一章　導論 1
1-1　前言 1
1-2　研究目的及方法 1
1-3　文獻回顧 1
1-4　本文研究 2
第二章　風洞試驗之基本理論分析 3
2-1　中性大氣紊流邊界層之風場特性 3
2-1-1　平均風速剖面 3
2-1-2　紊流強度剖面 5
2-1-3　紊流積分尺度 6
2-1-4　紊流能譜 7
2-2　中性大氣紊流邊界層之風洞試驗模擬 7
2-2-1　相似性法則 7
2-2-2　渦流產生器(spire)之設計原理 9
2-2-3　粗糙元素(roughness elements)之設計原理 10
2-3　高斯擴散理論 10
第三章　試驗配置與量測 13
3-1　試驗配置與設計 13
3-1-1　環境風洞介紹 13
3-1-2　中性大氣紊流邊界層之模擬 14
3-1-3　模型配置與設計 14
3-2　試驗流程 15
3-2-1　迫近流場(approaching flow)之量測 15
3-2-2　濃度場之量測 17
第四章　試驗結果與討論 21
4-1　迫近流場之模擬結果 21
4-1-1　平均風速 21
4-1-2　紊流強度 21
4-1-3　紊流能譜 21
4-2　濃度擴散分佈特性分析與討論 22
4-2-1　兩建築物等高之濃度擴散分佈 22
4-2-2　後棟建築物高為2H之濃度擴散分佈 23
4-2-3　各斷面垂直向濃度最大值之變化 24
4-2-4　各斷面擴散尺度之變化 24
4-2-5　改變棟距之影響 25
4-2-6　前後棟相對高度之影響 25
4-3　後棟建築物表面濃度分佈特性分析與討論 25
4-3-1　後棟建築物表面濃度分佈 25
4-3-2　後棟建築物迎風面中心濃度分佈比較 26
第五章　結論 27
參考文獻 29
附圖 31
附表 79
謝誌 81

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