本研究探討以點狀雷射加熱管壁至穩態後，再由管壁上的溫度分佈推算出管內流量之非侵入式流量量測法的可行性，內容包含實驗以及數值模擬兩部分，實驗將以點狀雷射加熱管壁，再利用紅外線熱相儀量測雷射熱點周圍的溫度分佈，並觀察改變管內流量對溫度分佈造成的影響；而數值模擬則將模擬軟體的計算結果與實驗結果作比對。由於雷射熱點的加熱面積與輸出功率皆相當小，管壁上的溫度分佈由熱傳導效應所主導，進而減弱熱對流效應的影響，因此與熱對流效應密切相關的流量對於溫度分佈造成之影響亦減弱。此外，僅有接近管壁的流體會受到熱源的影響而升溫，熱量難以藉由此處流體較低的流速傳遞至下游，使得管壁上無法明顯觀察到改變流速對溫度分佈造成的影響。實驗與數值模擬均顯示改變流量對溫度分佈造成的影響相當有限(小於3%)，以此方法量測管內流之流量的可行性並不高。若要以加熱管壁並量測管壁溫度分佈的方式來推算出管內的流量，宜使用熱傳導係數較低的管壁、減少管壁厚度、增加熱源面積以及增加輸入的熱量以改善此流量量測法。

This study discusses the feasibility of a non-intrusive flow measuring method, by heating the outer surface of the pipe with spot laser until steady state is reached. The flow rate is then calculated according to the temperature distribution of the pipe wall. The study includes experiment and numerical simulation. At various flow rates, the outer surface of the pipe is heated with spot laser in the experiment, then the temperature distribution around the heat spot is measured by an infrared camera. Numerical simulation is conducted and compared with the experimental results. Since the heating area and heating power are relatively small, the temperature distribution of the outer surface of the pipe is dominated by heat conduction. The effect of heat convection appears insignificant and only the slowly-moving fluid near the pipe wall is heated by the spot laser. Since the heat is not effectively carried downstream, changing flow rate exerts little effect on the temperature distribution. Experimental and simulation results show little changes of less than 3% in temperature distribution for wide variation of flow rate. Therefore the feasibility of this flow measuring method is questionable. However, improvement may be attained by using lower-thermal-conductivity wall materials, thinner pipe wall, and larger size and power of the heat source.

摘要 I
Abstract II
致謝 III
目錄 IV
圖表目錄 VI
符號表 X
第一章 緒論 1
1.1 研究背景 1
1.2 原理概述 2
1.3 文獻回顧 2
1.3.1 非侵入式的流量量測 3
1.3.2 非侵入式的熱對流係數量測 5
1.3.3管內流場受到不同面積之熱源加熱後的溫度分佈以及熱傳效應 18
1.4 研究動機 25
第二章 實驗方法 27
2.1 實驗設備與架構 27
2.2 實驗流程 29
2.3 實驗參數 31
第三章 數值模擬方法 34
3.1 幾何與數值模型 34
3.2 數值方法 36
3.3 模擬參數 37
3.4 網格設定與計算域建立 38
第四章 結果討論與可行性評估 42
4.1 實驗結果與討論 42
4.2 數值模擬結果與討論 48
4.3 可行性評估 55
第五章 結論 58
參考文獻 59

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