微灌毛管环状和树状布置对灌水均匀性的影响

为了提高微灌灌水质量,通过试验分别研究了毛管进口压力、长度、管径和滴头流量对毛管环状管网和树状管网灌水均匀度及其流量偏差率的影响。结果表明:两种管网结构下灌水均匀度均随毛管进口压力和毛管管径的增大而增大,随毛管长度和滴头流量的增大而减小,且相同条件下环状管网的灌水均匀度比树状管网高1%～2%;本试验条件下环状管网流量偏差率基本保持在20%以内,而树状管网流量偏差率则大于20%;环状管网灌水均匀度、流量偏差率随各因素变化的幅度小于树状管网。通过方差分析可得,毛管管径对两种管网灌水均匀度、流量偏差率影响均显著,滴头流量仅对树状管网灌水均匀度影响显著。所以,在微灌工程设计中可考虑采用毛管管网环状布置形式。     

地下滴灌田间管网灌水质量对土壤物理特性差异的响应

压力水头偏差率和滴头流量偏差率是评价微灌灌水质量的重要指标.在试验与地下滴灌毛管水力计算数学模型的基础上,建立了地下滴灌田间管网水力计算数学模型.利用该模型,分析了地下滴灌田间管网灌水质量对土壤物理特性差异的响应.结果表明,由于土壤物理特性对地下滴灌滴头流量的制约作用,致使地下滴灌田间管网压力水头与滴头流量偏差率比地表...     

微灌系统均匀度的保证率分析

本文将可靠性理论引入微灌系统灌水质量的评价中。因为微灌灌水均匀度或出流均匀度作为评价灌水质量的指标,它受许多具有不确定性因素的影响,文中分析了这些不确定因素在一定的概率分布条件下微灌单元灌水均匀度的保证率或可靠度。在文献的基础上分析了在一定坡度下,微灌系统均匀度的保证率计算。     

微灌灌水均匀度测试系统的设计

微灌是一种先进的节水灌溉技术，微灌均匀度系数是衡量微灌系统灌水均匀度的重要指标。为此，提出了一种基于AT89S51单片机的微灌灌水均匀度智能测试方式，此法可对微灌系统的均匀度进行快速测定，具有实际应用价值。     

低压滴灌系统研究

通过分析微灌技术的特点和应用现状，定义了低压滴灌系统的概念和原理，讨论了该系统的主要研究内容和现状，并提出流量偏差、灌水均匀度、灌水器工作压力的确定，以及滴灌系统关键设备的开发、研制是今后的研究重点。     

微地形影响下滴灌均匀度设计指标研究

首先对滴灌系统中田面微地形偏差、水力偏差、制造偏差三因素独立作用及共同作用下产生的滴头流量偏差率、偏差系数、均匀度的计算公式进行分析，对符合正态分布的田面局部高、滴头制造系数进行计算机模拟。并随机分配给滴头；然后借助计算机模拟计算出上述三种因素独立作用及共同作用下流量偏差率、偏差系数、均匀度等指标；最后将上述四种计算结果的500组数据。经过统计分析。确定了灌水均匀度计算公式，并建立了各均匀度参数之间的关系，分析得到的公式可直接用于滴灌系统的水力学计算。     

灌水器制造偏差系数测定试验研究

提出了一种测定微灌灌水器制造偏差系数的试验方法,分析了微灌灌水器出口压力对其制造偏差系数的影响,提出运用灌水器工作压力下的理论流量计算灌水器制造偏差系数,从而消除了压力对制造偏差系数的影响,并设计具体试验装置进行试验得到数据验证了上述试验方法。     

微灌均匀度参数之间的关系及其应用

本文通过模拟计算建立了微灌灌水均匀系数Ｃｕ与总的灌水器流量变差系数Ｃｒ和流量变差率ｑｖ，ｑｖａ及灌水器工作水头变差率ｈｗ，ｈｖａ之间的关系，并直接用于水力学计算，使微灌系统设计考虑灌水器制造偏差变得非常容易。     

灌水器制造偏差系数测定试验研究

提出了一种测定微灌灌水器制造偏差系数的试验方法，分析了微灌灌水器出口压力对其制造偏差系数的影响，提出运用灌水器工作压力下的理论流量计算灌水器制造偏差系数，从而消除了压力对制造偏差系数的影响，并设计具体试验装置进行试验，得到数据验证了上述试验方法。     

微灌均匀度参数之间的关系及其应用

本文通过模拟计算建立了微灌灌水均匀系数已与总的灌水里流量变差系数Ｃｖ和流量变差率ｑｖ、ｑ（ｖａ）及灌水器工作水头变差率ｈｗ、ｈ（ｖａ）之间的关系，并直接用于水力学计算，使微灌系统设计考虑灌水器制造偏差变得非常容易。     

An assessment of hydraulic design of micro-irrigation systems

The hydraulic design of micro-irrigation systems to achieve high system uniformity has led design engineers to over-design irrigation systems arbitrarily. Commonly used emitter flow variations of 10–20% are equivalent to a uniformity coefficient of about 98-95%, or a coefficient of variation of emitter flow of only 3–7%. The uniformity of a micro-irrigation system is affected by not only hydraulic design but also manufacturer's variation, grouping of emitters, plugging, soil hydraulic characteristics and emitter spacings. Among all the factors affecting the uniformity, the hydraulic design, with an emitter flow variation of 10–20%, produces only a few percent change in uniformity. The manufacturer's variation of micro-irrigation emitters ranges from 2% to 20%. The hydraulic variation will be less significant when an emitter with 10% or more manufacturer's variation is selected. The grouping effect will reduce the coefficient of variation to half or more if four or more emitters can be grouped together. The effect of hydraulic design is also less significant with plugging situations. When there is no plugging, the emitter flow variation from 10% to 20% in hydraulic design will reduce spatial uniformity only about 8% from 93% to 85% when the emitter spacing is designed as half of the wetting diameter in the field. The hydraulic design criterion can be relaxed to 30%v of emitter flow variation, q_var(H), which can still achieve less than 20%v in coefficient of variation, or over 80% of uniformity coefficient in spatial uniformity of a micro-irrigation system     

吸力式微润灌水器水力特性试验研究

在参照滴头水力特性检测方法的基础上,从流量变异系数、流量压力关系、水量分布均匀系数等角度研究了吸力式微润灌水器水力特性。结果表明,0.02MPa工作压力下微润灌水器流量变异系数均值为5%,流量变异系数随着压力的增大先减小后增大;流量随着工作压力的增加而明显增大,二者之间具有良好的幂函数关系;水量分布均匀系数在83%～93%之间变化,随工作压力的增加先增大后减小,为了尽可能保证灌水器出流量和灌水均匀,工作压力宜控制在0.018～0.025MPa之间。     

KD型大流量系列孔口滴头的研制

孔口滴头是微灌设备中重要的灌水器分支,通过对大流量系列滴头的研制,使我国的灌水器种类更加齐全。测出的此种滴头的水力性能参数,为微灌工程设计提供了重要的设计参数。     

基于二分法的微灌毛管水力设计

根据微灌毛管水力学特性,采用二分法搜索原理,并与逆递推法相结合,提出微灌毛管水力解析与设计方法。利用计算机编程从毛管末端向毛管进口逆序递推,可以快速、方便地求解出毛管各个孔口的压力和流量,设计毛管运行的水力参数,校核平均流量、流量偏差率等设计控制指标。实例验证结果表明,该设计方法具有直观、简便和快捷的特点,易为非专业人员理解与应用,具有较高的求解效率和计算精度。     

自压滴灌支管灌水单元设计方法

为了解决山地自压滴灌支管灌水单元水力设计问题,以滴头制造偏差、水力偏差和微地形偏差产生的综合流量偏差率作为灌水均匀度衡量标准,计算出支管灌水单元不同压力区允许水压力偏差和最大水压力,根据不同压力区支管水压力递推关系,确定出支管压力偏差分配系数,将支管单元设计转变为支管设计和毛管设计;支管设计采用两阶段设计法,计算出支管各节点水压力,根据该水压力和不同压力区允许最大水压力,对支管进行压力单元的划分,在不同压力区选择不同类型的滴头,使滴头额定工作压力与地形高差提供的工作压力相匹配．研究结果可直接用于山地支管灌水单元设计,计算可在Excel表格中完成,设计方法简单实用．     

Field evaluation of fertigation uniformity as affected by injector type and manufacturing variability of emitters

Fertigation with microirrigation systems is increasing in popularity. Uniformity of fertigation is important for many reasons. Field experiments were conducted to evaluate the effects of injector types and emitters on fertigation uniformity by simultaneously measuring the distributions of water application, solution concentration, and fertilizer applied within a subunit of microirrigation system. Three conventionally used injectors, a water-driven piston proportional pump, a venturi device, and a differential pressure tank, were evaluated with three different emitters. The results indicated that both manufacturing variability of emitters and injector types had a very significant effect on the uniformity of fertilizer applied, while the uniformity of water application was mainly dependent on emitter type. The uniformity of solution concentration was dependent on injection methods. Emitters having a higher manufacturer’s variation produced a more nonuniform distribution of water application and fertilizer applied. For a given emitter type, a differential pressure tank produced considerably higher coefficients of variation (Cv) for water application and fertilizer applied than a proportional pump or a venturi injector because a differential pressure tank released fertilizer in a decreasing rate with time. To obtain a uniform fertigation distribution, an injector that can inject fertilizers in a constant rate is recommended. The relationship between water application uniformity and fertigation uniformity for a microirrigation system was established for different injection methods. Cv for fertilizer applied was very close to water application Cv for a microirrigation system using a proportional pump or a venturi injector as an injection device. However, fertilizer Cv for a differential pressure tank was approximately double of the water application Cv. The injection method and injector performance should therefore be considered in the design of microirrigation systems.     

涌泉根灌灌水器抗堵性能试验研究

为了研究大流道涌泉根灌灌水器的水力性能及抗堵性能,在微灌产品测试平台上对其进行了水力性能和短周期抗堵测试,并与常规迷宫流道灌水器进行比较。结果表明,涌泉根灌灌水器流态指数为0.517,制造偏差为3.5%,属优等产品;在含沙水条件下,其出水均匀性高于95%;经强制加沙试验验证,涌泉根灌灌水器与常规迷宫流道灌水器相比,具有较强的抗堵塞能力,并且该灌水器流量大,适合旱地经济林灌溉。     

基于混合蛙跳算法的自压微灌管网系统优化设计

[目的]解决自压微灌管网系统布置与管径优化设计的问题,节省工程投资造价.[方法]以新疆某灌区一微灌工程为研究对象,以微灌系统中各级管道的管段长度、管径为决策变量,支毛管允许水头差、工作压力、管径、流速等为约束条件,以管网总投资最小为目标,分别建立了双向毛管布置和单向毛管布置的自压微灌管网数学模型,并采用混合蛙跳算法进行...