Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/10736
標題: 雙道固床工下游沖刷坑流場之PIV量測分析
Investigation of the Flow Field in the Scouring Holes Downstream of two Grade-Control Structures with a PIV System
作者: 溫啟倫
Wen, Chi-Lun
關鍵字: 質點影像測速儀;Scouring holes;沖刷坑;雷諾應力;底床剪應力;Particle Image Velocimetry;Reynolds stress;Bed shear stress
出版社: 土木工程學系所
引用: 1.台灣省水利局,防洪工程設計手冊,1969。 2.吳紋瑩,雙道固床工下游沖刷之室內試驗研究,中興大學土木工程研究所碩士論文,2012。 3.劉羽哲,明渠流通過固床工下游側沖刷坑之FLDV與PIV量測分析,中興大學土木工程研究所碩士論文,2012。 4.張凱博,變量流作用下之固床工沖刷室內試驗研究,中興大學土木工程研究所碩士論文,2010。 5.彭思顯,投潭水作用下局部沖刷之動態研究,中興大學土木工程研究所碩士論文,1994。 6.楊翰宗,陡坡光滑渠流水力特性之研究,中興大學土木工程研究所碩士論文,1998。 7. Breusers, H. N. C. and Raukivi, A. J., (1991). “Scouring” A. A. Balkema. 8.Breusers, H. N. C. (1966) “Conformity and time scale in two-dimensional local scour” Proc. Symposium on model and prototype conformity: 1-8, Hydraulic research Laboratory Poona (also Delft Hydraulic, Delft, Publication 40). 9.Bennett, S. J. and Alonso C. V., (2006) “Turbulent flow and bed pressure within headcut scour holes due to plane reattached jets” J. Hydraul. Res.,44(4), 510-521. 10.Farhoudi, J. and Smith, K. V. H. (1982). “Time scale for scour downstream of hydraulic jump” ASCE, 108(HY10), 1147-1161. 11.Farhoudi, J. and Smith, K. V. H., (1985). “Local Scour Profiles Downstream of Hydraulic Jump” J. Hydraul. Res., 23(4), 343-358. 12.Gaudio, R., Marion, A., and Bovolin, V. (2000). “Morphological effects of bed sills in degrading rivers” J. Hydraul. Res., 38(2), 89-96. 13.Gaudio, R. and Marion, A. (2003). “Time evolution of scouring 14.Hoffmans, G. J. C. M., anf Verheji, H. J. (1997). “Scouring manual” Balkema, Rotterdam, The Nethelands. 15.Hoffmans, G. J. C. M. (1990) “Concentration and flow velocity measurements in a local scour hole” Report 4-90, Faculty of civil Engineering, Hydraulic and Geotecnical Engineering Division, Delft Univercity of Technology, Delft. 16.Kurniawan A. and Altinakar, M. S., (2002). “Velocity and Turbulence measurements in a scour hole using an Acoustic Doppler Velocity Profiler” EPFL, Lausanne, Switzerland. 17.Meftah, M. B. and Mossa, M. M. (2006) “Scour holes downstream of bed sills in low-gradient channels” J. Hydraul. Res., 44(4), 497-509. 18.Melville, B. W. and Coleman, S. E. (2000) “Bridge Scour” Water Resources Publications, LLC., 193-196. 19.Nezu, I. and Rodi, W. (1986). “Open-channel flow measurements with a laser Doppler anemometer” J. Hydraul Eng., 112(5), 335-355. 20.Nezu, I. and Nakagawa, H. (1993). “Turbulent structures and bursting phenomena over roughness discontinuity in open channel flows” turbulent structures and related environment in various water flows, Scientific Research Activities, 122-129. 21.Nezu, I. and Nakagawa, H. (1993). “Turbulent in open-channel flows” Kyoto University ( in Japan ). 22.Oliveto, G., Comuniello, V. and Onorati, B. (2008) “Temporal development of local scour downstream of positive-step stilling basins” River flow 2008, vol. 2, 1673-1678. 23.Pagliara, S. (2007) “Influence of sediment gradation on scour downstream of block ramps” J. Hydraul. Eng., 133(11), 1241-1248. 24.Shields, A. (1936) “Anwendung der ahnlichkeitsmechanik und turbulenz forschung auf die geschiebebewegung” Mitteil. Preuss. Versuchsanst. Wasser, Erd, Schiffsbau, Berlin, Nr. 26. 25.Zanke, U. (1978) “Zusammenhange zwischen stromung und sediment transport” Mitt. Des Franzius Instituts der Univ. Hannover, Nr. 47,Nr. 48 (in German).
摘要: 
台灣地理環境特殊,洪峰期間河床沖淤劇烈,為穩固河床,工程上常利用固床工控制河床高程。惟水流通過固床工與河床交界面,於下游產生局部沖刷坑,嚴重時甚至造成水工結構物之毀壞或潰決。
近年來有關沖刷坑之研究多著重於平衡條件下最大沖刷深度之推估,對於沖刷坑之流場缺乏深入探討。惟沖刷坑之流場特性等物理現象,實為一重要之研究議題。
吾人於室內實驗渠槽設置雙道固床工,以質點影像測速儀 ( PIV ) ,於下游側形成之沖刷坑內流場進行量測實驗。量測之變數包括單位寬度流量、渠床坡度及流速歷程,主要分析項目包括:平均流速場、平均紊流強度、平均雷諾應力及底床總剪應力等。本研究主要目的為探討沖刷坑隨時間演變並趨緩穩定之歷程,其底床剪應力之變化與隨機特性。
實驗結果顯示,吾人於最大沖刷坑深度處所量測之總剪應力平均值,與希爾茲圖 ( Shields diagram ) 臨界剪應力平均值相距甚大。吾人將實測剪應力以機率分佈呈現,發現於沖刷坑發展前期沖刷劇烈,瞬間底床剪應力超過臨界起動剪應力之機率甚高,並隨沖刷坑之演化而逐漸遞減。其次,研究結果顯示,在不同實驗條件下 ( 變化坡度與單位寬度流量 ) ,此一物理現象具有可重複性。此外,本研究並針對沖刷坑內流場,進行平均與紊流水理參數之深入探討。

Due to the characteristics of Taiwan’s geographical features, the situation of scouring and depositing are quite severe during flood peaks. In order to stabilize the riverbed, it is common to use groundsill to control the riverbed elevation. While flow go through the interface between groundsill and riverbed, the roughness difference will cause the local scour, and even induce the hydraulic structure damages.
Recently most researches place their emphases on the evaluation of maximum scour depth research rather than the flow field of scour hole. However, the characteristics of the flow field are important research issues.
In this study, we use PIV system to measure the flow field in the scouring holes downstream of two grade-control structures. The independent variables include discharge, bed slope and duration of the scouring holes. The main variables measured are: mean velocity, turbulence intensity, Reynolds stress and bed shear stress etc.
Dual grade-control structures are established in an indoor flume experiment and Particle Image Velocimetry (PIV) is utilized to measure the flow field in the downstream scour holes in this study. The independent variables include the unit flow discharge and bed slope, and the major dependent variables analyzed include the average flow field, turbulence intensities, Reynolds stress, and bed shear stress. This study aims to explore the change and the random characteristics of the bed shear stress during the evolution of the scour holes. The experimental results show that although the mean bed shear stress measured at the deepest point of the scour hole is less than the critical shear stress based on the Shields diagram, the probability of instantaneous bed shear stress exceeding the critical shear stress is fairly high in the early stage of the scouring process, and it decreases gradually. The research results also show that the physical phenomenon is reproducible under different experimental conditions (changes of slope and unit flow discharge). Moreover, the mean and the turbulence parameters in the flow field of the scour holes.
URI: http://hdl.handle.net/11455/10736
其他識別: U0005-2108201313555600
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