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张学军 《农业工程技术:农产品加工》2000,(10)
五、喷头 喷头是喷灌系统最重要的部件,水通过它喷射到空中,散成细小的水滴,从而实现对作物的灌溉,亦称为灌水器。无论是在喷灌机中还是在管道式的灌溉系统中,喷头选用是否恰当以及性能的好坏,将对喷灌系统的经济性、可靠性和灌溉水的喷洒质量等起着决定性的作用。因此,在选择喷灌系统时首先应确定的是用什麽灌水器的问题。 喷头的种类很多 ,可按喷头的工作压力和射程分类,也可按结构形式和喷洒特征分类。目前国内常用喷头有摇臂式喷头和穿孔管两种。在大田灌溉中用得最普遍的是摇臂式喷头;在温室、大棚等固定场地是穿孔… 相似文献
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为缩短研发周期,减少成本,通过计算流体动力学(computer fluid dynamics,CFD)技术对风送式喷雾机的风送系统进行设计和优化,从最大限度地减小气流能量的损失和涡流、提高流场分布均匀性的原则出发,设计了最佳的风箱结构和具体参数。为实现根据树冠形状调整风送系统高度和倾角以适应不同生长时期不同类型的果园,通过CFD模拟计算和试验,探究了风送式喷雾机的气流速度和安装角度对气流速度场的影响规律,并模拟分析了喷雾机流场分布规律。在获取了风送距离与风送速度的关系(随着风送距离的增加,风速逐渐减小,减小的幅度也逐渐减小)后,建立了喷雾高度与喷头倾角的线性关系模型。结果显示:当喷头倾角大于85°或小于40°时,喷头倾角变化对于气流场的改变影响不大;当喷头倾角为40°～85°时,随着喷头倾角的增加,喷雾高度也相应地增加。本研究为实现仿形喷雾的自动化提供了理论依据。 相似文献
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<正> 中原12c6型喷灌机组是由中国农业科学院农田灌溉研究所、河南省水利厅农水处和南阳行署水利局修配厂、焦作标准件厂联合设计研制的一种小型人工移动管道式多喷头作业的喷灌机组。全机由12马力柴油机、水泵、胶轮手推车、机架、活动管道、喷头支架和摇臂式喷头等部分组成。适于在平原、缓坡丘陵地区对大田作物进行喷灌,也可喷灌同类地区的果树或林木苗圃。12c 型移动式喷灌机是由省机械厅农机所和新郑农机厂参考意大利喷头的优点,共同研制的产品,12c 喷灌机是柴油机为动力,依靠人力更换工作位置的小型移动式喷灌设备。 相似文献
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喷头是植保机械药液雾化的关键装置,其性能优劣对喷雾质量有重要影响。主要阐述了国外通用喷头、静电喷头、抗飘喷头和变量喷头技术的研究成果和应用发展状况,对现有技术成果进行了综合性评述。在通用喷头方面注重结构优化、材料性能与CAD技术应用研究,在静电喷头方面侧重喷雾系统优化、喷雾技术原理与产业化研究,在抗飘喷头方面关注喷头结构设计、喷雾方案优化与提高药效利用率方法研究,在变量喷头方面强调控制技术、元器件与新喷头开发的研究,并指出国外植保喷头注重新技术、智能化和精准化方面的研究较多,而在喷头管理、新理论应用方面研究较少,没有规范统一的编码制度及缺乏专业化的监控体系等问题。最后提出植保喷头技术应在注重与新机具配套开发、制造技术要专业高精化、建立健全的编码制度和专业监控体系方面引起更多重视,以使其进一步为农林业发展服务。 相似文献
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设计一种气助式静电感应喷头,对其工作原理和关键结构进行了研究。在室内对它进行了雾化性能试验和荷电效果试验。由试验结果分析了充电电压、气体压力与流量、液体压力与流量、喷孔直径等参数对雾化质量和荷电效果的影响,综合分析气体压力为0.4 MPa,液体压力为0.25 MPa,喷孔直径为2.0 mm时气助式静电感应喷头具有最优化性能。 相似文献
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植保常用扇形雾喷头系列型谱模型研究 总被引：1，自引：0，他引：1
《山西农业大学学报(自然科学版)》2016,(7)
[目的]为了实现植保常用扇形雾喷头的数字化管理及生成,促使喷头设计与生产向协调、统一、择优、简化方向发展。[方法]对常用扇形雾喷头的结构组成、性能特征、喷雾质量进行了理论分析,对不同终端型式的扇形雾喷头进行了雾型分布试验。[结果]雾型分布受喷嘴终端型式影响较大。最终建立了不同系列喷头的型谱模型,制定了扇形雾喷头谱系结构。[结论]此研究为相关软件开发与数据库建立提供了支持与参考,便于喷头的快速检索与参数化设计,研发和生产新型植保喷头。 相似文献
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Effects of water application uniformity using a center pivot on winter wheat yield,water and nitrogen use efficiency in the North China Plain 
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下载免费PDF全文 In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain(NCP). The combined effects of water and nitrogen application uniformity on the grain yield, water use efficiency(WUE) and nitrogen use efficiency(NUE) have become a research hotspot. In this study, a two-year field experiment was conducted during the winter wheat growing season in 2016–2018 to evaluate the water application uniformity of a center pivot with two low pressure sprinklers(the R3000 sprinklers were installed in the first span, the corresponding treatment was RS; the D3000 sprinklers were installed in the second span, the corresponding treatment was DS) and a P85 A impact sprinkler as the end gun(the corresponding treatment was EG), and to analyze its effects on grain yield, WUE and NUE. The results showed that the water application uniformity coefficients of R3000, D3000 and P85 A along the radial direction of the pivot(CU_H) were 87.5, 79.5 and 65%, respectively. While the uniformity coefficients along the traveling direction of the pivot(CU_C) were all higher than 85%. The effects of water application uniformity of the R3000 and D3000 sprinklers on grain yield were not significant(P0.05); however, the average grain yield of EG was significantly lower(P0.05) than those of RS and DS, by 9.4 and 11.1% during two growing seasons, respectively. The coefficients of variation(CV) of the grain yield had a negative correlation with the uniformity coefficient. The CV of WUE was more strongly affected by the water application uniformity, compared with the WUE value, among the three treatments. The NUE of RS was higher than those of DS and EG by about 6.1 and 4.8%, respectively, but there were no significant differences in NUE among the three treatments during the two growing seasons. Although the CU_H of the D3000 sprinklers was lower than that of the R3000, it had only limited effects on the grain yield, WUE and NUE. However, the cost of D3000 sprinklers is lower than that of R3000 sprinklers. Therefore, the D3000 sprinklers are recommended for winter wheat irrigation and fertigation in the NCP. 相似文献
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To adapt to the trend toward low-energy precision irrigation, the droplet distributions for two new prototype sprinklers, outside signal sprinkler(OS) and fluidic sprinkler(FS), were compared with impact sprinkler(IS). A laser precipitation monitor was used to measure the droplet distributions. Droplet size and velocity distributions were tested under four operating pressures for nozzles 1.5 m above the ground. For the operating pressures tested, the mean OS, FS and IS droplet diameters ranged from 0 to 3.4, 0 to 3.5, 0 to 4.0 mm, respectively.The mean OS and FS droplet velocities ranged from 0 to6.3 m$s–1, whereas IS ranged from 0 to 6.3 m$s–1. Being gas-liquid fluidic sprinklers, droplet distributions of the OS and FS were similar, although not identical. IS mostly produced a 0.5 mm larger droplet diameter and a 0.5 m$s–1greater velocity than OS and FS. A new empirical equation is proposed for determination of droplet size for OS and FS, which is sufficiently accurate and simple to use. Basic statistics for droplet size and velocity were performed on data obtained by the photographic methods. The mean droplet diameter(arithmetic, volumetric and median)decreased and the mean velocity increased in operating pressure for the three types of sprinkler. 相似文献
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As water supplies become limited, agricultural water use needs to become more efficient to maintain current productivity levels. The efficiency of center pivot and linear move irrigation systems can be increased by matching the amount and rate of water application to specific soil conditions that vary in the field. Such site-specific application can be achieved by variable-rate control systems. Although such systems are being developed, their effects on center pivot and linear move uniformity have not been documented. The uniformity along the length of a center pivot and a linear move irrigation system was measured at two system movement speeds and three variable-rate settings. One variable-rate system is commercially available using pneumatically actuated solenoid valves to turn groups of sprinklers ON and OFF at fractions of a minute corresponding to the cycle rate, for example a 50% cycle rate is 30 s ON and 30 s OFF. The other variable-rate system used commonly available electric solenoid valves to accomplish the same task. Overall, the coefficient of uniformity and low quarter distribution uniformity averaged 93% and 0.90, respectively for the center pivot irrigation system; 84% and 0.74 for the linear move system. The results were not significantly (P > 0.05) affected by wind speed, cycling rate, or system movement speed. The type of nozzle did influence the uniformity because of the distinctly different application characteristics of rotator, fixed plate, and wobbling low pressure sprinklers. Thus, the variable-rate technologies tested under the conditions presented in this paper had at least as good uniformity as the center pivot and linear move systems when functioning in non-variable-rate mode.Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the University of Florida or the University of Georgia and does not imply approval of a product or exclusion of others that may be suitable. 相似文献
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The objective of this research was to assess the effect of soil cracks on soil moisture distribution under various sprinkler
irrigation applications and to identify the optimal irrigation strategy that enhances soil moisture distribution and reduces
water drainage for the upper soil layer 0–250 mm. The assessment was made for six irrigation events: the first two were for 10 and 46 mm water applications using a hand shift-set
sprinkler system. The second set was for 43 and 19 mm water applications using the lateral move system with fixed sprayer
heads and the third pair of events were for 43 and 32 mm water applications using the lateral move system with rotating sprinklers.
The experiments were conducted on two adjacent fields at the University of Queensland, Gatton, Australia. Each field was divided
into 2 m × 2 m grids that covered 62 sampling locations. For each event, the initial soil moisture content (SMC) was measured
at each sampling location before irrigation. After irrigation, catch can readings were recorded for each sampling location.
After 12 h overnight, the second set of soil moisture measurements was taken at each location. The area1 distribution of SMC
for the studied applications was quantified. An attempt was made to identify the relationship between the applied water uniformity
using catch cans and the soil moisture uniformity using gravimetric water content measurements. The study also took into consideration
variables that could affect the soil physical and hydrological properties including the field slope, the soil texture, the
infiltration rate, the salt content and the soil organic matter content of the two fields. Since the soils were cracking clay
Vertisols, further analyses were conducted on the crack dynamics, size and distribution using image analysis techniques. The
research findings demonstrated that the cracks were the main contributors to water drainage below 250 mm soil depth due to
the micro-run off from the crust surface to the cracks. The cracks ranged from a few millimeters to more than 40 mm in width.
It was observed that the cracks which were wider than 15 mm remained open after irrigation for the specified application rates.
Improving the irrigation system application uniformity did not always result in higher uniformity of the surface SMC (0–250 mm).
The event that best enhanced soil moisture distribution and thus improved soil moisture recharging was observed after the
sixth irrigation event when the field received 32 mm water application. The soil was at a relatively high initial SMC of 25%,
(which represented 43.3% of the plant available water range) and the sprinkler water uniformity was rather high above 87%
Christiansen coefficient of uniformity (CUc). At this SMC, the extent of soil cracking is limited. 相似文献
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为了加快节水灌溉技术推广和普及,采用内生转换回归模型分析农户节水灌溉技术采用行为,并评估节水灌溉技术的增产效应,结果表明,节水灌溉技术的增产效应十分显著,能够使农户每hm2胡萝卜产量增加约7 961kg,相当于单产水平的21%。户主受教育程度、家庭在外务工人数和技术采用经历对农户节水灌溉技术采用行为影响显著;生产规模大、参与产销合作的农户也会更倾向于采用节水灌溉技术。根据研究结论,本研究最后提出了4点政策建议:1)努力提升农户受教育程度;2)积极推进耕地适度规模经营;3)大力推广产销合作模式;4)加强节水灌溉技术推广力度。 相似文献
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通过田间试验,研究了覆膜沟灌条件下不同水氮处理对番茄产量与品质的影响,旨在探讨西北旱区覆膜沟灌条件下番茄的水肥调控模式,以达到节水、增产、高效与优质的目的。结果表明：采用85%对照灌水量处理（CK）对番茄
市场产量（≥60 g）无显著影响,而65%和45%对照灌水量处理则减产明显;采用3/4当地施肥量(CK)处理对番茄总产量与市场产量影响不显著;减少灌水量处理显著增加番茄的果色指数与硬度,提高可溶性固形物、可溶性糖含量,降低有机酸含量;施氮量对番茄可溶性固形物、有机酸含量影响不显著,但减少施氮量增加可溶性糖含量;番茄维生素C含量随灌水量与施肥量的降低呈现先增加而后降低的趋势。综合考虑产量、品质及水分利用效率(WUE),本研究认为采用416.76 mm（85%CK）灌水量及117.6 kg·hm-2（3/4CK）纯氮施用量,为西北旱区覆膜沟灌种植条件下适宜的水肥调控模式。 相似文献
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Evaluations of emitter clogging in drip irrigation by two-phase flow simulations and laboratory experiments 总被引：2，自引：0，他引：2
Wei Qingsong Lu Gang Liu Jie Shi Yusheng Dong Wenchu Huang Shuhuai 《Computers and Electronics in Agriculture》2008,63(2):294-303
Emitter clogging will affect greatly the irrigation efficiency and the running cost of a drip irrigation system. If there is an effective method to predict the emitter clogging, the lost will be reduced to a minimum. A solid–liquid two-phase turbulent model describing the flow within drip emitters was studied. Then, the moving trace and depositing feature of suspending solids in emitter channels were obtained by computational fluid dynamics (CFD) based on the turbulent model established, which provided some visual and direct evidences for predicting the clogging performance of drip emitters. The three types of emitters with novel channel form, including eddy drip-arrows, pre-depositing drippers and round-flow drip-tapes, developed by us were used in this study. The simulation results showed that the solids moved along a helical path in the eddy drip-arrow, but no obvious deposition existed in its interior channel. In the pre-depositing dripper, some solids concentrated in the parts of “depositing pones”. In the round-flow drip-tape, a small number of solids adhered to the out-edges of every channel corner, which was a potential factor for the occurrence of emitter clogging. To verify the predictions from the CFD simulations, series of “short-cycle” clogging tests for the three emitters were conducted in laboratory. The statistical data of discharge variation caused by emitter clogging were in good agreement with the two-phase flow CFD simulations. 相似文献
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不同灌水方式下干旱区盐碱地土壤水盐运移特征分析 总被引：8，自引：0，他引：8
采用滴灌、漫灌和沟灌的灌溉方式,分析了新疆干旱区典型盐碱地灌水前后土壤水分、盐分时间和空间运移规律.结果表明,滴灌后表层土壤含水量水平差异较沟灌、漫灌大;滴灌形成近倒圆锥型的土壤湿润区,沟灌则形成近似U型的土壤湿润区;滴灌在湿润层外围形成盐壳,沟灌的沟顶部分在返盐的作用下形成积盐,漫灌总体压盐效果较滴灌和沟灌好;与沟灌... 相似文献