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標題: 陡坡渠槽之摻氣流場特性研究
Investigation on the two-phase flow field of a chute flow with a bottom aerator
作者: 李彥德
Yen-Der Li
關鍵字: Chute flow;Air entrainment;Two-phase flow;Particle image velocimetry (PIV);Bubble image velocimetry (BIV);Fiber optic reflectometer (FOR);陡坡流;摻氣;兩相流;PIV技術;BIV技術;FOR技術
引用: 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。
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.
其他識別: U0005-2811201416180922
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