Calculation of optimal compound cross-section dimensions channel with flat-bottom and parabolic side walls
ZHAI Donghan1, HE Wuquan1,2*, LI Gang1
1.College of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100, China; 2.Key Laboratory of Agricultural Soil & Water Engineering in Arid and Semiarid Areas, Ministry of Education, Yangling, Shaanxi 712100, China
Abstract：To solve a few problems such as great depth and large amount of earthworks occurred when a parabolic cross-section is applied in large- and medium-sized channels, a channel with compound cross-section was proposed, which is subject to a flat bottom and two 2th-order parabolic side walls. Analytical formulas for determining the channel cross-sectional area and wetted perimeter were deduced. Based on the open-channel uniform flow theory, a relationship between flow and water depth was established for the channel when the channel cross-section profile was under optimal hydraulic condition. Additionally, a series of formulas for the optimal width-to-depth ratio, water depth, water surface width, cross-sectional area and wetted perimeter were deduced and programmed by using Mathcad software. It was shown that at flow Q=30 m3/s, the channel had 2.904 m water depth, 6.278 m water surface width and 13.604 m2 cross-sectional area under the optimal hydraulic condition. The channel cross-section area is 1.7% and 0.2% smaller than the channels respectively with ordinary trapezoidal cross-section, arc-bottomed trapezoidal cross-section at the same flow rate. This indicates that the proposed compound cross-section profile is better in hydraulics and earthwork cost in comparison with the two kinds of existing trapezoidal cross-section channels.
翟东汉, 何武全,*, 李刚. 平底抛物线形复合渠道水力最佳断面计算方法[J]. 排灌机械工程学报, 2018, 36(3): 204-208.
ZHAI Donghan, HE Wuquan,*, LI Gang. Calculation of optimal compound cross-section dimensions channel with flat-bottom and parabolic side walls. Journal of Drainage and Irrigation Machinery Engin, 2018, 36(3): 204-208.
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