T型管在工業工程中被廣泛應用。為認識T型管冷熱流體混合的相關機理，以國立清華大學T型管裝置為類比物件開展了數值研究。通過使用大型商業CFD軟體Fluent，模擬T型管內的冷熱流體在不同流速比下熱混合和熱振盪現象，分別使用穩態RANS湍流模型模擬流體熱混合特性，和使用瞬態LES分析熱振盪的頻率特性。通過模擬研究發現，不同流速比下T型管內流體呈現出不同流態，在支主管流速比較大的情況下，T型結處會發生回流現象；揭示了不同管路佈置(下游帶彎管)對T型管下游溫度波動的持續的影響。類比結果與實驗資料符合良好。

T-junctions are widely used in engineering. Based on experiments already done by NTHU, this research continue to use the commercial CFD software, Fluent ,to simulate the phenomenon of thermal mixing and thermal stripping of fluids with different temperature in T-junction at different flow rates. The steady state turbulence model RANS is used to simulating the flow characteristics of thermal mixing, and the unsteady state turbulence model LES is used to analyze the frequency characteristics of thermal stripping. It is found that the fluid in the T-junction exhibited different flow pattern at different flow ratios. Under the condition that the flow rate of the branch pipe to main pipe is relatively large, reverse flow occurs at the T-junction. The simulation results presented in average temperature are in good agreement with experimental data. The simulation also reveals that downstream elbow has a constant influence on temperature fluctuation downstream of the T-junction by swirling the fluid ,which is also called Dean vortex.

中文摘要 i
英文摘要 ii
誌謝 iii
目錄 iv
表目錄 vi
圖目錄 vii
符號對照表 ix
第一章 緒論 1
1.1 研究背景與目的 1
1.2 研究目的與方法 3
第二章 文獻回顧 4
第三章 實驗簡介 8
3.1 實驗裝置 8
3.2 實驗流程 10
3.3 實驗條件 10
第四章 幾何模型與數學模型建立 12
4.1 幾何模型 12
4.1.1 湍流尺寸 13
4.1.2 邊界層網格設置 14
4.2 統禦方程 14
4.2.1 RANS模型 14
4.2.2 LES模型 14
4.3 邊界條件設置 15
4.4 模型空間離散和時間離散設定 15
4.5 SGS亞格子模型 16
第五章 直管T型管基準驗證 18
5.1 網格獨立性分析 18
5.2 RANS不同湍流模型評估 19
5.3.1 溫度與速度雲圖 23
5.3.2 流態與流線分析 33
5.4 模擬與實驗驗證 35
5.4.1 平均溫度 35
5.4.2 PSD頻域分析 40
第六章 下游90度彎管的T型管內流動 45
6.1 PSD頻域分析 46
6.2 流線分析 52
第七章 結論與展望 54
參考文獻 55

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