基于拉格朗日法的抛物线形复合渠道的水力最佳断面

发布时间：2018-04-24 19:40

本文选题：渠道 + 水力最佳断面　；参考：《灌溉排水学报》2017年11期

【摘要】：针对标准抛物线形渠道渠口宽、深度大、难以适应大中型渠道等问题,提出了一种新型平方抛物线形渠坡和水平渠底的抛物线形复合渠道,同时推导出了抛物线复合渠道水力要素计算公式,并以水深、水面宽度和水平渠底宽度为变量,利用拉格朗日乘数法建立求最优解的迭代方程,借助Mathcad数学软件进行计算,推导出了抛物线复合渠道水力最佳断面情况下流量和水深的关系式以及水深、水面宽度、过水断面面积和湿周的计算公式。通过实例计算,当流量Q为12 m~3/s时,在水力最佳断面情况下抛物线复合渠道的水深H0为2.263 m,水面宽度B0为4.538 m,过水断面面积A0为7.463 m~2。结果表明,相同流量下抛物线复合渠道的过水断面面积比梯形渠道减小了1.67%,比弧脚梯形渠道减小了0.84%,比抛物线形渠道减小了1.05%,表明抛物线形复合渠道是更为优越的渠道断面形式。
[Abstract]:A new type of parabola channel slope and horizontal channel bottom is proposed to solve the problems of wide channel opening, large depth and difficult to adapt to large and medium-sized channel, a new type of parabola channel slope and horizontal channel bottom is proposed. At the same time, the calculation formula of hydraulic factor of parabolic composite canal is derived, and the iterative equation for finding the optimal solution is established by using Lagrange multiplier method, taking the depth of water, the width of water surface and the width of horizontal channel bottom as variables, and the calculation is carried out by Mathcad software. The relationship between discharge and water depth and the calculation formulas of water depth, water surface width, cross section area and wet circumference of parabolic composite canal under the optimal hydraulic section are derived. The calculation results show that when the flow rate Q is 12 m / 3 / s, the water depth H _ 0 is 2.263 m, the water surface width B _ 0 is 4.538 m, and the cross section area A _ 0 is 7.463 m ~ (2) under the optimal hydraulic section condition, the water depth H _ 0 is 2.263 m, the water surface width B _ 0 is 4.538 m, and the cross section area A _ 0 is 7.463 m / m. The results show that At the same flow rate, the cross section area of the parabolic composite channel is 1.67 smaller than that of the trapezoidal channel, 0.84 of the trapezoidal channel at the arc foot, and 1.05 of the parabolic channel, which indicates that the parabolic composite channel is a more superior channel section form.
【作者单位】：西北农林科技大学水利与建筑工程学院;旱区农业水土工程教育部重点实验室;
【基金】：国家“十三五”重点研发课题(2016YFC0400203)
【分类号】：TV133

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