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1.
An improved method for designing microirrigation submain units 总被引：1，自引：0，他引：1
A method was developed for designing microirrigation submain units using the lateral flow rate equation, finite element method,
and golden section search. Characteristics of water application uniformity affected by lateral parameters (length and diameter)
and submain parameters (length and diameter) were analyzed using computer simulations. The design principle was then implemented
based on the simulation results. When the required average emitter discharge, the required water application uniformity, one
lateral parameter (length or diameter), and one submain parameter (length or diameter) are given, the optimal values of another
lateral parameter, another submain parameter, best submain position (paired laterals), and operating pressure head can be
accurately designed using a personal computer. A submain unit designed using this method has a minimal initial cost. This
method is suitable for both submain units with uniform lateral lengths (in regular fields) and nonuniform lateral lengths
(in irregular fields).
Received: 28 May 1996 相似文献
2.
Design of microirrigation laterals at minimum cost 总被引：1，自引：0，他引：1
Based on the design methods of finite elements and golden-section searches, a method was developed for designing microirrigation
laterals at minimum cost. Characteristics of water application uniformity as affected by lateral diameters and lengths were
analyzed. When the required average emitter discharge is known, the relationships of water application uniformity, best submain
position (paired laterals), and operating pressure head as a function of the lateral diameter and length can be accurately
determined using a personal computer. The lateral diameter and length can then be determined from a contour map representing
water application uniformity as a function of the lateral diameter and length (computer calculation). The best submain position
and operating pressure head for this lateral diameter and length is then determined by computer calculation. This method is
suitable for designing microirrigation laterals on both uniformly and nonuniformly sloping fields.
Received: 30 May 1997 相似文献
3.
4.
基于遗传算法的微灌坡地双向毛管管径优化 总被引：2，自引：1，他引：2
微灌管网毛管的设计,直接影响到工程费用和灌水质量。提出了一种基于遗传算法的坡地双向毛管管径的优化方法,能获得毛管最优管径和灌水器平均流量、灌水均匀度等灌水质量控制指标,同时能确定毛管最佳分流点位置和毛管进口压力等运行控制参数。实例结果表明,模型与算法的求解时间为9s,计算精度达到0.001%,具有很好的通用性和实用性。 相似文献
5.
J. M. Tarjuelo J. Montero F. T. Honrubia J. J. Ortiz J. F. Ortega 《Agricultural Water Management》1999,40(2-3):315-331
One of the most appropriate sprinkler systems for arid or semi-arid areas – where a great deal of irrigating water is required – are the permanent set systems and the continuous-move laterals. To know the reality of water application in this type of areas, many field evaluations of solid set systems and centre pivot irrigation were conducted in Castilla-La Mancha region (Spain). The main factors affecting water application and evaporation and drift losses with these systems (pressure, wind speed, sprinkler type, etc.) were analysed. A set of performance guidelines and recommendations for the design and management of sprinkle irrigation is presented to attain the highest uniformity and efficiency in water application in semi-arid areas. To use working pressure as low as possible, but with sprinklers that produce a great deal of middle size water drops along with night irrigation for minimising evaporation and drift losses are important aspects. 相似文献
6.
A simple procedure was developed for the design of low-cost, gravity-fed, drip irrigation single-manifold subunits in hilly
areas with laterals to one or both sides of the manifold. The allowable pressure head variation in the manifold and laterals
is calculated individually for different pressure zones, and the manifold subunit design is divided into independent processes
for laterals and manifold. In the manifold design, a two-stage optimal design method is used. In the first design stage, the
pipe cost is minimized and a set of optimal manifold pipe diameters is obtained. In the second design stage, a partial list
of available diameters is prepared based on the calculated optimal diameters, and the lengths for available diameters and
pressure head of every lateral location along the manifold are calculated. The size of each of the pressure sections is determined
according to the pressure head distribution along the manifold. Using the proposed methodology, the minimum manifold pipe
cost is obtained, and the target emission uniformity is satisfied for gravity-fed drip irrigation subunits. 相似文献
7.
为了提高滴灌系统水力设计的准确性,基于有限元原理,提出一种计算薄壁内镶贴片式滴灌带能量损失和灌水均匀度的方法,局部水头损失根据贴片式滴头结构、管内压力和管道壁厚确定,沿程水头损失通过改进Darcy－Weisbach公式编写计算机程序,分析了不同滴灌带的水头损失及均匀度变化规律,并与《微灌工程技术规范》中推荐计算方法的结... 相似文献
8.
Numan Mizyed 《Irrigation and Drainage Systems》2002,16(1):53-68
A model to solve the hydraulics of trickleirrigation units is developed in thisstudy. This model is based on utilizingNewton Raphson technique. The modelconverts laterals into equivalent outletsthrough utilizing a simple power relationbetween inlet lateral discharge andhydraulic head. This relation is obtainedthrough least squares analysis betweeninlet lateral discharge and hydraulic head. This study showed that this relation withonly two coefficients is sufficient todescribe the relation between inlet lateraldischarge and hydraulic head. Based onthis relation, the model converts manifoldlines into equivalent laterals and solvestheir hydraulics by Newton Raphsontechnique. After that solution, the modelevaluates trickle irrigation units byestimating statistical uniformity andChristiansen uniformity coefficients andchecks the solution obtained throughforward step method for each lateral. Several numerical examples for utilizingthe model are presented in this paper.Palestine Authority 相似文献
9.
机压喷灌干管管网优化 总被引：2，自引：0，他引：2
在考虑了机压管道式喷灌系统配水干管流量变化的基础上，提出了这一系统干管管网优化的线性规划模型及计算方法。应用这一方法，可在保证各支管入口处所需流量和压力的条件下，确定水泵扬程及干管尺寸最优值，以使干管管网系统年费用值达最小 相似文献
10.
Field evaluation of fertigation uniformity as affected by injector type and manufacturing variability of emitters 总被引：2，自引：1，他引：2
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. 相似文献
11.
12.
A study was conducted at the department of Agricultural Structure and Irrigation, Harran University, Sanliurfa, Turkey, to
determine the effect of increased irrigation water temperature at various irrigation system pressures on emitter flow rate,
lateral elongation, and Standard Flow Rate Index for six different brands of drip laterals. Test materials consisted of seven
pressure and seven non-pressure compensating irrigation laterals from different manufacturers. Tests results showed that (a)
tensile resistance stress tests indicated that 25% elongation levels were reached at about 40 kg of load. On average, pressure
compensating laterals reached 25% elongation at 38 kg, while non-pressure compensating laterals reached 25% elongation at
32-kg load. There was no clear indication of the tested brands’ lateral wall thickness on the measurement, (b) pressure-regulated
drip emitters had no or limited flow rate change due to increased irrigation water temperature, whereas non-pressure compensating
emitters had significantly (P < 0.05) increased flow rates, and (c) finally, increased irrigation water temperature resulted in decreased flow rate variations
that had a positive effect on standard deviation. Standard uniformity values improved with decreased flow rate variations
in drip emitter flow rates. 相似文献
13.
为了阐明滴头制造偏差系数、灌水均匀度、毛管直径及毛管造价的内在联系,降低滴灌系统造价、提高灌水均匀度,通过理论推导结合实证计算的方法,系统分析了不同均匀度条件下滴头制造偏差系数极限值,以及滴头制造偏差系数、毛管直径、允许均匀度等三者的关系,并推导出毛管造价计算公式.结果表明:对于长度为100 m的毛管,当Keller均匀系数( EEU)为0.80时,制造偏差系数从0.05增大到0.07和0.11时,毛管造价分别增大8.7％和37.1％;当滴头制造偏差系数为0.03, EEU由0.80增大到0.85,0.90和0.95时,毛管直径分别增大20％,23.5％和56.5％,毛管造价也相应增大20％,53.8％和207.7％;当滴头制造偏差系数为0.05, EEU由0.80增大到0.85和0.90时,毛管直径则分别增大19.3％和32.8％,毛管造价也分别增大17.1％和71.4％;对于 EEU为0.95时,毛管允许最小流量大于平均流量,管径计算无解.在限定值范围内,滴头制造偏差系数和Keller均匀系数的微小增大将直接导致毛管直径和造价急剧增大;滴灌系统设计应选择制造偏差系数小的滴头及合理的灌水均匀度,以达到降低工程造价的目的. 相似文献
14.
L. Mateos 《Irrigation Science》1998,18(2):73-81
The procedure established in the literature for the evaluation of stationary sprinkler irrigation systems is limited in space
and time since it is based on a sample of precipitation taken around one sprinkler during a given period of the whole irrigation
event. This procedure also ignores what happens in the soil after water infiltrates. A model of the drop trajectory and of
the water distribution pattern is formulated here for simulating precipitation from single sprinklers. The operating pressure
determines sprinkler flow and maximum throw. Wind and evaporation distort the distribution patterns. The water distribution
of individual sprinklers is overlapped to generate precipitation over the whole field and to calculate a coefficient of uniformity.
Field effective uniformity is then calculated by averaging precipitation over the extension of plant roots or water redistribution
within the soil profile. Application of the model has shown the impact of system management and design, field topography and
wind on irrigation uniformity. Management factors such as lateral operation time or riser inclination may account for a large
part of the field precipitation variations. A rough topography may also reduce uniformity significantly. Wind speed is important
when it exceeds 1.8–2 m s–1. The allowable maximum pressure loss of 20% fixed as a design criterion seems an overly strict limit when other factors may
overcome pressure loss as sources of non-uniformity. The sources of non-uniformity have different scales of variation. Large-scale
sources, such as lateral operation time or pressure loss, are not dampened by the crop or soil. Sources of smaller-scale variation,
such as wind or inclination of the sprinkler riser, are better compensated by the crop and soil. The application of this kind
of model to the design and management of sprinkler irrigation systems is discussed.
Received: 9 May 1997 相似文献
15.
低压条件下滴灌灌水均匀度试验研究 总被引：3，自引：0，他引：3
低压滴灌毛管进口工作压力、铺设长度、地面坡度及毛管管径是影响滴灌灌水均匀度的重要参数。试验研究结果表明,低压条件下毛管进口压力的变化对灌水均匀度的影响并不明显;灌水均匀度随着毛管铺设长度的增大呈降低趋势,管径越小,降低越显著,但在一定管长范围内,毛管铺设长度对灌水均匀度的影响并不明显;逆坡情况下,灌水均匀度随着坡度的增大而减小,顺坡情况下,灌水均匀度随着坡度的增大呈先增大而后减小的趋势,在2‰的坡度时达到峰值;灌水均匀度随着管径的增大而增大,当管径增大到一定程度后,灌水均匀度随管径增大的幅度减缓。 相似文献
16.
Pedro Vallesquino 《Irrigation Science》2008,26(6):475-486
A new method for simulating lateral hydraulics in laminar or turbulent flow has been developed. The outflow is considered
as a discrete variable and the friction head losses are calculated using the Darcy–Weisbach equation with an equivalent friction
factor. Local head losses are also computed by applying equivalent coefficients that can be dependent on Reynolds number.
Considering these premises, a compact expression that is valid for any type of regime has been deduced for calculating global
head losses along any lateral stretch. The proposed method is useful to workout the hydraulic computation of laterals with
the inlet segment at full or fractional outlet spacing, and complex laterals when a different pipeline diameter, slope, flow
regime or emitter gap have to be considered. 相似文献
17.
通过单喷头雨量分布室内试验,获取雨量分布信息及出水轨迹信息.利用三维建模、粒子系统等虚拟现实技术,结合实际的雨量分布数据及出水轨迹,模拟出喷头喷洒水雾的三维动态模型.研究喷灌机各跨同步行走时前进方向喷灌雨量分布均匀性,实现前进速度的最优化.分析喷头配置间距和喷头高度对横向灌溉均匀度的影响,优化平移式喷灌机喷头配置.在进行单喷头雨量分布室内试验的基础上,建立了雨量分布仿真模型.仿真结果和现场试验表明：改变驱动电机的频率可以实现纵向的变量灌溉,横向的灌溉均匀度取决于喷头的型号和压力,田间与仿真试验得到的水分分布数据最大相对误差为3.39%,证明仿真模型的可信度.为平移式喷灌机同步行走控制条件下变量控制对灌溉效果的影响和优化研究提供了手段. 相似文献
18.
《Agricultural Water Management》2005,71(2):167-179
The present investigation was undertaken to evaluate the effect of various levels of water and N application through drip irrigation on seed cotton yield and water use efficiency (WUE). In this experiment three levels of water (Epan 0.4, 0.3, and 0.2) and three levels of N (100, 75, and 50% of recommended N, 75 kg/ha) through drip were compared with check-basin method of irrigation under two methods of planting (normal sowing, NS; paired sowing, PS). The results revealed that when the same quantity of irrigation water and N was applied through drip irrigation system, it increased the seed cotton yield to 2144 from 1624 kg/ha (an increase of 32%) under check-basin method of irrigation. When the quantity of water through drip was reduced to 75%, the increase in seed cotton yield was 12%; however, when water was reduced to 50%, it resulted 2% lower yield than check-basin. The decrease in N through fertigation resulted in reduction in seed cotton yield at all the levels of water supply, but the magnitude of reduction was the highest at highest level of water supply. In paired sowing (PS), 20% higher seed cotton yield was obtained as compared with check-basin method under NS along with 50% saving of water. In paired sowing the sacrifice of 9% seed cotton yield as compared with NS resulted in saving of 50% water as well as the cost of laterals because there was one lateral for two paired rows. The WUE increased by 26% (22.1 from 17.6 kg/ha cm) in drip irrigation system when same quantity of water and N fertilizer was applied as compared with check-basin. WUE was not affected with quantity of water but decrease in rate of N caused a decrease in WUE at all the quantities of water applied. In general, WUE was higher in PS as compared with NS. The agronomic efficiency of nitrogen increased from 21.65 to 28.59 kg of seed cotton per kg of N applied when same quantity of water and N was applied through drip irrigation as compared with check-basin. However, decrease in quantity of water applied resulted in a decrease in agronomic efficiency of N but reverse was true for rates of N applied. When the same quantity of water and N was applied under both the methods of planting, PS produced 22% higher seed cotton yield and along with reduced cost owing to half the number of laterals required. 相似文献
19.
Dimensional analysis approach to estimate local head losses in microirrigation connectors 总被引：1，自引：0，他引：1
Danieli Bariviera Zitterell Jose Antonio Frizzone Osvaldo Rettore Neto 《Irrigation Science》2014,32(3):169-179
Local losses, which affect the uniformity of water application, are often ignored in the design of irrigation systems. Some accessories have no simple, efficient equations to estimate these losses. The main objective of this work was to develop an equation to estimate the local head loss in lateral passage connectors. Fifteen connector/pipe combinations were tested. The connectors were characterized by their internal diameters and dimensions. The local head loss was determined by subtracting the head loss on the connector and pipe from the head loss on the pipe. The parameters affecting the local head loss were defined as dimensionless terms using Buckingham’s theorem. A mathematical model was developed that presented a determination coefficient of 93.31 %. Elements such as the inner diameter of the connector, pipe length, connector, water flow velocity, Reynolds number and Froude number influenced the local head loss in the connectors. The model was compared with the observed data and presented excellent performance. It can be used to calculate the local head loss in lateral passage connectors. 相似文献
20.
基于二分法的微灌毛管水力设计 总被引：2，自引：0，他引：2
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。 相似文献