Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/10263
標題: 坡度跌流工沖擊流場機制之研究
Study on Hydraulic Characteristics of Free Overfall Impacted Flow Downstream of a Sloping Drop Structure
作者: 劉希羿
Liu, Shi-I
關鍵字: 跌流工
Drop Structure
沖擊流場
坡度效應
視窗化模式
Impacted Flow Field
Slope Effects
Windows-Based Model
出版社: 土木工程學系所
引用: 1..余常昭(1999),「明槽急變流-理論和在水工中的應用」,清華大學出 版社,第182-185頁。 2..宋爾寧(1999),「帶工法對投潭水流行為及沖刷特性之影響」,國立中興大學土木工程學系,碩士論文。 3..林呈(2005),「河川橋樑之橋墩(台)沖刷保護工法之研究(第二冊)」,交通部公路總局專案研究計畫,第8章,第70-86頁。 4..梁文壇(1998),「跌水迴水區之水理分析」,國立中央大學土木工程學系,碩士論文。 5..陳正炎、郭信成(1994),「堰壩投潭之沖刷坑特性及其坡度效應研究」,第七屆水利工程研討會論文集,第B263-B274頁。 6..陳正炎、蔡建文(1995),「堰壩投潭水流沖擊力之研究」,中華水土保持學報,第26卷,第2期,第135-144頁。 7..陳正炎、黃宏信、劉希羿、闕河杰、徐垚鉉(2010),「自由跌水流作用於坡度渠床之能量損失試驗研究」,台灣水利,第58卷,第1期,第68-78頁。 8..陳聖文(2000),「防砂壩下游帶工佈置之試驗研究」,國立中興大學土木學系,碩士論文。 9..陳建富(2002),「單階自由跌水之數值模擬」,私立中原大學土木工程學系,碩士論文。 10.黃宏信(2010),「自由跌水作用下坡度渠床之水力特性研究」,國 立中興大學土木工程學系,博士論文。 11..Chamani, M.R., and Beirami, M.K. (2002). “Flow characteristics at drops.” Journal of Hydraulic Engineering, ASCE, 128(8), 788-791. 12..Chanson, H. (1995). Hydraulic design of stepped cascades, channels, weirs and spillways. Pergamon, Oxford, UK. 13..Chanson, H. (1996). “Discussion on energy loss at drop.” Journal of Hydraulic Research, IAHR, 34(2), 273-278. 14..Chen, J.Y., Yao, C.Y., Liao, Y.Y., and Huang, H.S. (2008). “Impact force on downstream bed of weir by free overfall flow.” Journal of the Chinese Institute of Engineers, 31(6), 1047-1055. 15..Davis, A. C., Ellett, B. G. S., and Jacob, R. P.(1998). “Flow measurement in sloping channels with rectangular free overfall” Journal of Hydraulic Engineering, ASCE, 124(7), 760-763. 16..Davis, A. C., Ellett, B. G. S., and Jacob, R. P.(1999). “Estimating trajectory of free overfall nappe.” Journal of Hydraulic Engineering, ASCE, 125(1),79-82. 17..Gill, M.A. (1979). “Hydraulics of rectangular vertical drop structures.” Journal of Hydraulic Research, IAHR, 17(4), 289-302. 18..Hager, W. H.(1983). “Hydraulics of plane free overfall.” Journal of Hydraulic Engineering, ASCE, 109(12), 1683-1697. 19..Ippen, P.J.(1943). Engineering hydraulics. John Wiely and Sons, Inc., New York, 570. 20..Lin, C., Hwung, W.Y., Hsien, S.C., and Chang, K.A. (2007). “Experimental study on mean velocity characteristics of flow over vertical drop.” Journal of Hydraulic Research, IAHR, 45(1), 33-42. 21..Moore, W.L. (1943). “Energy loss at the base of a free over-fall.” Transactions, ASCE, 108, 1343-1360. 22..Rajaratnam, N., and Chamani, M.R. (1995). “Energy loss at drop.” Journal of Hydraulic Reserch, IAHR, 33(3), 373-384. 23..Rand, W. (1955). “Flow geometry at straight drop spillways.” Journal of Hydraulic Engineering, ASCE, 81, 1-13. 24..Rouse, H. (1936). “Discharge characteristics of the free overfall.” Civil Engineering, 6(4), 257-260. 25..Tokyay, N.D., and Yidiz, D. (2007). “Characteristics of free overfall for supercritical flows.” Canadian Journal of Civil Engineering, 34(2), 162-169. 26..Vischer, D.L., and Hanger, W.H. (1995). “Energy dissipators.” IAHR Hydraulic Structures Design Manuals 9, Taylor & Francis, USA. 27..White, M.P. (1943). “Discussion on energy loss at the base of a free over-fall.” Transactions, ASCE, 108, 1361-1364.
摘要: 水利工程常於河道中設置攔河堰、跌水工、固床工、防砂壩等抬水跌流消能構造物,以達到穩定取水、調整河道縱坡、控制上游泥砂來源及維護橋樑安全等目標。然因抬水致生跌流,下游渠床在跌流水舌沖擊力與剩餘能量作用下,易導致跌流工下游消能設施損毀,失去原先較佳消能效果,因此,跌流工沖擊流場機制之研究甚為重要。往昔研究跌流工沖擊流場機制,幾乎以跌流工上游渠床坡度為零之「自由跌流工」為對象,惟據台灣22條主要河川資料統計,跌流工上游因淤砂導致跌流工上游渠床坡度大於2%者占68%,因此跌流工上游渠床已具坡度形成「坡度跌流工」,其跌流前流速已驟增,破壞力更勝於自由跌流工,坡度跌流工沖擊流場機制為何,實應深入探究。 本研究經由坡度跌流工沖擊流場機制理論推導後,再運用室內定量清水渠槽試驗,針對跌流工上游不同渠床坡度S (=0~6%)、不同跌流高度H (=0.15~0.30 m)進行跌流試驗。試驗過程以超音波水位計及下游渠床設置不干擾流場壓力計,擷取量測坡度跌流工各種沖擊水力特性相關數據加以分析探討,並經由試驗結果驗證坡度跌流工各沖擊水力特性之物理量理論式,其結果本研究理論式與試驗資料迴歸經驗式均能有效估算試驗值,並經驗證後可實際應用於實務。另由本研究坡度效應可知在坡度S=6%時,無因次跌流沖擊位置(L_d/H)、無因次跌流單寬沖擊力(〖F_d/ρgH〗^2,ρ=水體密度、g=重力加速度)、無因次能量損失(∆E/Y_c,Y_c=臨界水深),較自由跌流工分別增加53.5%、33.2%及41.7%。 另本研究亦將試驗迴歸之經驗式,運用Visual Basic程式語言撰寫一視窗化模式軟體,模擬跌流工上游流況、跌流沖擊水力特性及力與能量等數據,並將呈列於圖表中,可使工程師於水工結構物之設計上更為便捷。
For the purposes of water intake, riverbed slope adjustment, sand source control and maintenance of bridge safety, cross-river structures have been widely constructed in rivers, such as weirs, overfalls, ground sills and check dams. These structures raise upstream water levels and cause overfall flows. Downstream riverbeds and energy dissipation structures could be damaged by impact forces of overfall flows. Thus, study of impacted flow fields of overfalls is very important. Most previous studies focused on impacted flow fields for overfalls with level upstream riverbeds, so called “level overfalls”. According to statistics from 22 important rivers in Taiwan, 68% of check dams have upstream riverbed slopes greater than 2% due to sediment deposition, so called “inclined overfalls”. Impact forces of inclined overfalls are actually greater than those of level overfalls. Therefore, it is worth to further study the impacted flow fields of inclined overfalls. This study carried study out a series of indoor flume experiments of free overfalls under steady flow conditions for various upstream bed slopes (S=0~6%) and drop heights (H=0.15~0.30 m). The longitudinal pressure distributions along the downstream channel bed were measured by a set of pressure transducer system, which was installed without affecting the existing flow field. In addition, to reveal slope effect of upstream bed slopes, theoretical equations associated with impacted hydraulic characteristics were validated by experimental data. According to slope effects developed by this study, the dimensionless drop position(L_d/H), unit width impacted force (〖F_d/ρgH〗^2,where ρ=water density and g=gravity acceleration) and energy loss (∆E/Y_c,where Y_c=critical depth) of a S=6% inclined overfall were 53.5%, 33.2% and 41.7% greater than those of a level overfall respectively. Due to rapid progress in computer technology, engineers now are able to design hydraulic structures with remarkable computing power. This study develops a windows-based model, which incoporates empirical regression equations form experimental work. It can show upstream flow conditions, hydraulic characteristics, impact force and energy dissipation on charts through model calculation. Therefore, it is expected to be much faster than in the past for the design of hydraulic structures.
URI: http://hdl.handle.net/11455/10263
其他識別: U0005-2907201311160800
文章連結: http://www.airitilibrary.com/Publication/alDetailedMesh1?DocID=U0005-2907201311160800
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