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標題: 應用 CCHE2D 數模於跌流工水力特性之影響
The Effect on Hydraulic Characteristics of Drop Structure by Using CCHE2D Numerical Model
作者: 林漢昌
關鍵字: Free Overfall;Drop Structure;Impact Position;CCHE2D Numerical Simulation;自由跌流;跌流工;沖擊位置;CCHE2D 數模
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. 陳聖文 (2000),「防砂壩下游帶工佈置之詴驗研究」,國立中興 大學土木工程學系,碩士論文。 3. 徐垚鉉 (2010),「超臨界自由跌流沖擊水力特性之研究」,國立 中興大學土木工程學系,碩士論文。 4. Chamani, M.R., and Beirami, M.K. (2002). 'Flow characteristics at drops.'Journal of Hydraulic Engineering, ASCE, 128(8), 788-791. 5. Chanson, H. (1995). 'Hydraulic design of stepped cascades, channels, weirs and spillways,' Pergamon, Oxford, UK. 6. Chanson, H. (1996). 'Discussion on energy loss at drop,' Journal of Hydraulic Research, IAHR, 34(2), 273-278. 7. 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. 8. 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. 9. Ferro, V. (1992). 'Flow measurement with rectangular free overfall,' Journal of Irrigation and Drainage, ASCE, 118(6), 956-964. 10. Gill, M.A. (1979). 'Hydraulics of rectangular vertical drop structures,'Journal of Hydraulic Research, IAHR, 17(4), 289-302. 11. Hager, W. H. (1983). 'Hydraulics of plane free overfall,' Journal of Hydraulic Engineering, ASCE, 109(12), 1683-1697. 12. Ippen, P.J. (1943). 'Engineering hydraulic,' John Wiely and Sons, Inc., New York, p.570. 13. 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. 14. Rand, W. (1955). 'Flow geometry at straight drop spillways,' Journal of Hydraulic Engineering, ASCE, 81, 1-13. 15. Tokyay, N.D., and Yidiz, D. (2007). 'Characteristics of free overfall for supercritical flows,' Canadian Journal of Civil Engineering, 34(2), 162-169. 16. White, M.P. (1943). 'Discussion on energy loss at the base of a free over-fall,'Transactions, ASCE, 108, 1361-1364.
水利工程經常於河道中設置橫向跌流工、攔河堰或防砂壩等水利設施,主要係為減緩上游來水及來砂作用力。惟高水位跌流時,上、下游易產生位動能差之變化,加促水舌沖擊力,而造成沖刷潛勢坑,不僅導致跌流工基腳淘空或損毀,同時削減河道內橫向構造物消能之效果。根據臺灣 965 座河川、野溪防砂壩資料統計中,其堰壩上游因淤砂導致渠床坡度小於 6 %者占全部防砂壩之八成二 當水流於上游渠。床呈現非水帄時之自由跌流,又下游渠床亦有坡度變化時流場機制為何?故應用室內渠槽詴驗或數值模擬,以探究上、下游具坡度影響跌流工之流場效應,即顯重要。
本文就自由跌流之跌流工邊緣水深(Yb)、沖擊位置(Ld)及尾水深(Y1)等水力特性,先採用 6 組既有渠槽詴驗之結果,進行 CCHE2D 之數值模擬跌流工流場。藉由比較兩者結果之差異,以及檢定誤差屬可信賴區間,獲致驗證數值模擬之可行性。進一步,再以 CCHE2D 模擬跌流工上、下游渠床坡度同時變化(Su 、 Sd =2、4 及 6%),構成 9 種不同詴驗條件之組合,以預測上游正常水深(Y0)、跌流工邊緣水深(Yb)、沖擊位置(Ld)及尾水深(Y1)之結果。研究結果獲致本 CCHE2D 數模,可提供相關自由跌流工未來物理詴驗之應用。

For dissipation of acting forces from upstream water and sediment, the cross-river structures such as free overfalls, weirs or check dams have been widely used in both natural and artificial channels. But the structures could be damaged or footing is eroded due to the impact forces of the free overfall variation. Their energy dissipation efficiencies are also reduced simultaneously. According to the statistics of 965 check dams in Taiwan, the average slopes of 82 percent are less than 6 percent due to the sediment deposition. It is worth studying the characteristics of flow field when the free overfall from the non-horizontal upstream impacts the downstream with varied slopes. The study uses the indoor channel test and numerical simulation to find out the effect of flow field with varied up- and down-slopes.
This study carries out the numerical simulation of free overfall flow field using CCHE2D. Six existing channel testing results are adopted for comparison with various free overfall brink depth of water (Yb), impact position (Ld), and tail depth of water (Y1). Through the comparison between numerical simulation and testing results, and examination of reliable range for error, the numerical simulation is verified for further application. Then, the CCHE2D is used to simulate the upstream and downstream slopes Su, Sd (0, 2, 4, and 6 %), and nine series of objects are assembled. The normal upstream depth of water (Y0), brink depth of water (Yb), impact position (Ld) and tail depth of water (Y1) can be evaluated. The analyzed results above can be provided in the application of physical test of drop structure.
其他識別: U0005-2606201511423900
Rights: 不同意授權瀏覽/列印電子全文服務
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