臺灣博碩士論文加值系統

陡槽通氣流場往往伴隨著大量氣泡吸入水體，產生二相流之現象，過去的研究少有針對流場中氣泡區之生成機制與運動特性進行探討。本研究嘗試運用陰影成像法，將流場中的氣泡生成過程予以可視化，進行定性觀察，並結合質點影像測速儀(簡稱PIV)與氣泡影像測速儀(簡稱BIV)量測技術，針對水躍流場中非氣泡區與氣泡區進行量測，進一步計算平均速度場。配合可視化所觀察之氣泡運動情形，且利用光纖反射儀(簡稱FOR)量測技術，對流場特性加以探討。
本研究主要針對三組不同來流水深進行量測與分析，並依流場之定性特性，將流場區分為：(I)來流區；(II)通氣區；(III)撞擊區；(IV)發展區等四個區域，來流區定義為跌水斷面上游段(X < 0)之區域；通氣區定義為空氣腔之區域，跌水斷面下游段(X > 0)至楔形尖趾處；由楔形尖趾處開始，至水舌上水面之延伸線與渠槽底部連結處，此範圍稱為撞擊區；接續撞擊區之後區段到氣泡完全發展至水表面，則泛稱為發展區。並針對各區之相關特性及氣泡生成機制與運動模式進行探討。此外，本研究另針對楔形尖趾處，量測氣泡體積濃度剖面，並探討來流水深與摻氣量之相關性。至於PIV量測系統、BIV量測系統之原理及景深控制、影像平均法及光纖量測訊號等技術，本文亦有所探討說明。

The characteristics of free-surface profile and air-concentration distribution along a chute flow around an aerator model, both in the sliding jet over air cavity and in the aerated flow right downstream of the wedged tip of air cavity, were investigated in past several decades. However, many previous researches mainly focused on the distributions of the air concentration due to the limitation of velocity measurement technique of two phase flow. Therefore, the aim of the present study is to investigate the flow structure in the aerated region using BIV, and the counterpart outside the aerated region using PIV. The mean flow and turbulence properties are obtained by ensemble averaging a large number of repeated instantaneous velocity measurements. Moreover flow visualization technique and FOR measurement technique are combined to explore the characteristics of the flow field.
According to the result observed qualitatively by using visualization technique, the flow region could be classified into four regimes as: (1) approach flow region, (2) aeration region, (3) impact region and (4) developing flow region. This study also investigates the mechanism of air entrainment and modes of motion in the flow region. Furthermore, the air concentration profiles downstream of the wedged tip and the relationship between air entrainment and approaching flow depth are also studied in this thesis.

摘 要 I
Abstract II
目 錄 III
符號說明 VI
第一章 緒論
1-1 研究動機 1
1-2 文獻回顧 3
1-3 本文組織 5
第二章 實驗儀器設備及佈置
2-1 實驗水槽 7
2-2 實驗模型佈置與流場座標系統 7
2-3 PIV量測系統及實驗佈置 12
2-3-1. 雷射光源系統 12
2-3-2. 高速攝影機 12
2-3-3. 流場追蹤物質 13
2-4 陰影成像可視化佈置及BIV量測系統 16
2-5 FOR量測系統 16
2-6 三維精密移行機構 17
第三章 速度量測、分析方法原理
3-1 具高時間解析之PIV系統量測原理 20
3-1-1 PIV量測原理 20
3-1-2 具高時間解析度PIV系統 21
3-2 BIV量測系統 25
3-3 FOR量測原理 29
3-4 陡槽通氣流場量測影像 32
3-5 影像平均法 37
第四章 初步實驗及實驗條件
4-1 光纖訊號分析 41
4-2 FOR率定試驗 48
4-3 因次分析 52
4-4 實驗條件 53
第五章 陡槽通氣流場之可視化定性觀測結果
5-1 陡槽通氣流場之區域分類 54
5-2 由側壁觀察陡槽通氣流場 56
5-2-1 整體流況 56
5-2-2流場通氣區 58
5-2-3流場撞擊區 63
5-2-4流場發展區 73
5-3 由底部觀察楔形尖趾周邊之流場 78
第六章 陡槽通氣流場之PIV、BIV與FOR定量量測結果
6-1 陡槽通氣流場之平均速度場特性 88
6-1-1 流場通氣區之速度分佈 99
6-1-2 流場撞擊區之速度分佈 102
6-1-3 流場發展區之速度分佈 105
6-2 楔形尖趾處之局部氣泡體積濃度量測 108
6-2-1氣泡體積濃度之二維性檢測 108
6-2-2來流水深與摻氣量之驗證 111
第七章 結論與建議
7-1 結論 115
7-2 建議 116
參考文獻 117
附錄A 口試委員審查意見答覆表 A-1
附錄B 各條件下之無因次雷諾剪應力 B-1
附錄C h0/H = 0.72之氣泡體積濃度剖面 C-1

1. Chanson, H. (1994). “Aeration and de-aeration at bottom aeration devices on spillways.” Canadian Journal of Civil Engineering, Vol. 21, No. 3, June, pp. 404 - 409 (ISSN 0315-1468).
2. Gaskin, S., Aubel, T., and Holder, G. (2003). “Air demand for a rampoffset aerator as a function of spillway slope, ramp angle and Froude number.” Proceedings of the 30th IAHR Congress, D, Thessaloniki, Greece, pp. 719 - 724.
3. Juli?, J. E., Harteveld, W. K., Mudde, R. F., and Akker, H. E. A. Van den. (2005)“On the accuracy of the void fraction measurements using optical probes in bubbly flows.” Review of Scientific Instruments, Vol. 76, 035103.
4. Koschitzky, H. P., and Kobus, H. (1988). “Hydraulics and design of spillway aerators for cavitation prevention in high speed flows.” Internation Symposium on Hydraulics for High Dams, IAHR, pp.724 - 733.
5. Kramer, K., and Hager, W. H. (2005). “Air transport in chute flows.” International Journal of Multiphase Flow, Vol. 31, Nos. 10-11, pp. 1181 - 1197.
6. Kramer, K., Hager, W. H., and Minor, H. E. (2006). “Development of air concentration on chute spillways.” Journal of Hydraulic Engineering, ASCE, Vol. 132, No. 9, pp. 908 - 915.
7. Lim, H. J., Chang, K. A., Su, C. B., and Chen, C. Y. (2008). “Bubble velocity, diameter, and void fraction measurements in a multiphase flow using fiber optic reflectometer.” Review of Scientific Instruments, Vol. 79, 125105.
8. Pan, S., Shao, Y., Shi, Q., and Dong, X. (1980). “The self-aeration capacity of the water jet over the aeration ramp.” Journal of Hydraulic Engineering (Shuili Xuebao), Beijing, China, No. 5, pp. 13 - 22 .
9. Pfister, M. (2011). “Chute aerator: steep deflectors and cavity sub-pressure.” Journal of Hydraulic Engineering, ASCE, Vol. 137, No. 10, pp. 1208 - 1215.
10. Pfister, M., and Hager, W. H. (2010a). “Chute aerators (I): air transport characteristics.” Journal of Hydraulic Engineering, ASCE, Vol. 136, No. 6, pp. 352 - 359.
11. Pfister, M., and Hager, W. H. (2010b). “Chute aerators (II): hydraulic design.” Journal of Hydraulic Engineering, ASCE, Vol. 136, No. 6, pp. 360 - 367.
12. Pinto, N. L., Neidert, S. H., and Ota, J. J. (1982). “Aeration at high velocity flows.” Water Power and Dam Construction, No. 34, February/March, pp. 34 - 38 and 42 - 44.
13. Pinto, N. L., and Neidert, S. H. (1983). “Evaluating entrained air flow through aerators.” Water Power and Dam Construction, No. 35, August, pp. 40 - 42.
14. Rutschmann, P., and Hager, W. H. (1990). “Air entrainment by spillway aerators.” Journal of Hydraulic Engineering, ASCE, Vol. 116, No. 6, pp. 765 - 782.
15. Ryu, Y., Chang, K. A., and Lim, H. J. (2005). “Use of bubble image velocimetry for measurement of plunging wave impinging on structure and associated greenwater.” Measurement Science and Technology, Vol. 16, pp. 1945 - 1953.
16. 田宗謀，2009，「潛堤附近碎波氣泡之實驗研究」，博士論文，國?成功大學水?及海洋工程學系，台南
17. 林怡如，2009，「應用PIV與BIV量測系統於水躍流場特性之探討」，碩士論文，國立中興大學土木工程研究所，台中
18. 陳逸芬，2008，「應用PIV於水躍速度場之分析探討」，碩士論文，國立中興大學土木工程學系，台中。
19. 謝世圳，2008，「建置具高時間解析度之PIV系統並應用於圓柱近域尾流特性之探討」，博士論文，國立中興大學土木工程學系，台中。