水保所知识产出(1956---)知识库

满足灌水均匀度设计标准与额定流量的滴灌毛管管径优化设计是滴灌毛管水力设计的重要内容。该文以流量偏差率为灌水均匀
度设计标准，提出一种简易的滴灌毛管管径水力设计方法。通过改变单向和双向滴灌毛管流量偏差率解析公式的形式，提出一个新的管
径设计参数。基于能坡线法，建立参数与坡降比参数的关系，并绘制和构建相关图形和计算公式。结果表明：当流量指数分别取值为1.75、
1.69 和1.00 时，单向毛管管径的设计参数取值分别为−1～≤2.801，−1～≤2.859 和−1～≤4；双向毛管管径的设计参数取值分别为0～≤
3.143，0～≤3.183 和0～≤4。满足流量偏差率设计标准和灌水器额定流量时，单向毛管管径将有1 或2 个设计值，双向毛管管径将有1、
2 或多个设计值。根据参数的取值范围，以坡降比参数为设计变量，推导了均匀坡下单向和双向毛管管径的计算公式。此外，进一步简化
了滴灌毛管进口工作水头的计算公式。当已知设计流量，流量偏差率设计标准，毛管管长等参数时，可以按照设计步骤直接计算滴灌毛
管管径和进口工作水头，无需进行任何复杂的试算。设计案例1 表明在多数地形条件下，利用该文方法设计单向毛管的结果与传统方法
设计结果的相对误差不超过4%；设计案例2 表明该文方法设计双向毛管的结果与其他2 种常用方法设计结果的最大相对误差为4%。因
此，从工程实践角度，利用该方法设计的滴灌毛管管径和进口工作水头与其他传统方法设计结果非常接近。相比于传统设计方法，该方
法简便实用，可以直接应用于滴灌工程设计。该研究可为改进滴灌毛管优化设计提供理论依据。

A simple, direct, and easily adaptable analytical approach was developed for determining the appropriate diameter of
the drip laterals laid on uniformly sloping grounds. The emitter flow variation was used as the index of water application
uniformity. A diameter design parameter was developed by reformulating the analytical expressions of emitter flow variation of
the single inlet lateral and paired laterals. The relationship between parameter and pressure loss ratio were expressed by the graphs
and formulas. For the specific value of velocity exponent, the condition for designing the diameter of a single inlet lateral was the
calculation parameter lying between -1 and ≤2.801, between -1 and ≤2.859 and between-1 and ≤4, respectively; meanwhile,
the condition for designing the diameter of the paired laterals was the calculation parameter lying between 0 and ≤3.143,
between 0 and ≤3.183 and between 0 and ≤4, respectively. On the other hand, for the required emitter flow variation and
emitter design discharge, there would be one or two solutions of diameter for a single inlet lateral, and one, two or numerous
solutions for the paired laterals. Based on the ranges of the parameter, the design equations for the diameter of the single inlet
lateral and paired laterals were derived with the pressure loss ratio as the design variable. The analytical expressions of inlet
working pressure head of drip laterals were also simplified based on the energy gradient line method. When the emitter design
flow, emitter flow variation criterion, and lateral length were provided, the diameter and inlet working pressure head of the drip
laterals could be easily calculated without performing complex computer operations or tedious computations. In case 1, the
differences in the designed parameters of a single inlet lateral from the proposed approach and variable discharge method are less
than 4% for most ground slopes. In case 2, the maximum deviation in the design parameters of the paired laterals from the
proposed approach and previous two methods was ≤4%. These 2 cases indicated that the proposed approach could produce
accurate results as those of the previous methods for practical purposes. By using the developed analytical expressions and
regression relationships, the proposed approach provided a more simplified and adaptable design procedure than the traditional
methods. This research could provide valuable information for improving the hydraulic design of drip irrigation system.