滴灌灌水器流道设计理论研究若干问题的综述

灌水器是滴灌系统最关键的部件之一,其结构与水力性能的优劣对滴灌系统的灌水均匀性、抗堵塞能力以及寿命影响很大。在简要论述国内外滴灌灌水器流道发展现状的基础上,从灌水器流量压力关系、流道内流体流动机理、流道堵塞与防治三个方面详细阐述了灌水器流道设计理论的研究进展,最后提出了滴灌灌水器流道的发展趋势以及国内在灌水器流道设计理论研究中急需解决的问题。     

基于CFD三维数值模拟的新型蠕动式滴灌灌水器水力性能研究

灌水器是滴灌系统中的核心部件。滴灌技术在农业节水灌溉系统中发挥着举足轻重的作用。针对传统滴灌灌水器流道易堵塞,结构较复杂,流量不稳定等缺点,提出一种新型蠕动式滴灌灌水器。该灌水器以转轮为核心部件,水流推动转轮间歇挤压具有较好弹性的软管,达到定时定量输水的目的。基于CFD三维数值模拟技术,对该滴灌器内部流道结构进行模拟,得到流量-压力关系式。蠕动滴灌器提高了滴头流道的抗堵性能,具有"自清洗"功能;装置结构简单,便于使用和安装。     

高钙镁离子地下水滴灌施肥系统堵塞效应

为了分析高钙镁离子地下水滴灌条件下施肥系统堵塞风险及综合影响效应,开展了大田春玉米田间滴灌试验.选择地下水和再生水2种灌溉水源,使用圆柱型迷宫流道灌水器和片式灌水器两类灌水器进行试验,并从灌水器堵塞及其对作物生长、产量的影响角度,对比分析了高钙镁离子地下水、再生水滴灌施肥的安全性问题,结果表明:该种高钙镁离子质量浓度(180 mg/L)地下水滴灌施肥比40~60 mg/L的再生水滴灌施肥具有更大的系统安全性问题;高钙镁离子地下水滴灌系统灌溉7次后灌水器相对平均流量Dra降至77.6%,灌水器均匀度CU降至79.9%,比再生水滴灌还低3.0%和5.3%,春玉米植株株高、茎粗、产量及水分利用效率分别比再生水降低7.4%,3.5%,3.7%,3.7%.研究可为合理利用地下水滴灌提供参考.     

引黄滴灌条件下混配水对堵塞物质表面特征的影响

为探明引黄滴灌条件下黄河水与微咸水混配对滴灌系统灌水器堵塞物质表面特征的影响,选择黄河水（YR）、微咸水（SW）以及黄河水和微咸水1∶1混配水（MW）3种水源,针对灌水器流道内易形成堵塞物质的位点,进行堵塞物质形成过程的模拟培养,借助三维白光干涉形貌仪观测并分析灌水器内部堵塞物质的表面形貌及变化特征,结果表明：黄河水与微咸水混配后堵塞物质表面凸起少,较为平坦;堵塞物质的厚度、表面均方根偏差、表面展开面积比率显著降低。其中,系统运行结束时（800h）,混配水条件下堵塞物质的平均厚度为4.39μm,分别比黄河水、微咸水条件下低65.32%、32.51%,这充分说明黄河水和微咸水混配后可有效缓解灌水器堵塞。     

滴灌灌水器流道堵塞及防治研究进展

滴灌的堵塞问题一直是困扰滴灌技术应用与发展的限制性因素,为了探索解决或者预防该问题的技术途径,从堵塞的成因、机理以及预防措施等方面进行了论述,提出了预防灌水器堵塞的基本措施,包括改进灌水器流道结构、强化水质处理以及严格过程管理。在此基础上,对今后的重点研究方向提出了若干建议。     

再生水滴灌条件下灌水器抗堵塞试验研究

随着新农村的建设,农村污水处理系统建设逐渐完善,同时节水灌溉技术的推广,农村再生水的利用成为农业灌溉节水的一种新方法。本试验针对农村污水处理系统,进行再生水滴灌试验。结果表明:市场常见的灌水器产品对农村的再生水有一定的适用性,具有抗堵塞的功能,可在农村推广再生水滴灌技术。宽齿形灌水器具有自清洗功能,抗堵塞性能优于其他3中灌水器,且大流量的灌水器的抗堵塞性能优于低流量的灌水器。由微生物与固体颗粒团体等组成的生物膜易沉积于灌水器的格栅和出水口缓冲区,引起灌水器堵塞,其是直接诱发灌水器堵塞的原因。灌水器流道内沉积物质的随机生长与脱落,造成灌水器的堵塞是一种随机的过程。滴灌系统运行大概350h,应对其进行清洗,以提高灌水器的抗堵塞性能。     

内镶式反滤防堵塞灌水器及滴灌管的研制和应用技术研究

目前国内外内镶式灌水器设计和生产中普遍采用的在灌水器上直接设置单一紊流态细小流道的生产工艺,在实际应用中存在着滴头易堵塞、对水质要求高等问题,为此,研制内镶式反滤防堵塞灌水器及滴灌管,既能防物理性堵塞,还能防生物性和化学性堵塞,解决滴灌系统灌水器的易堵塞难题,不仅可用于常规的地表滴灌,还可用于地下滴灌和灌溉施肥。     

再生水条件下灌水器内生物膜生长对流量的影响

选用生物泳动床、生物滤池两种污水处理工艺下的再生水进行滴灌试验,研究灌水器内生物膜的生长情况。结果表明:灌水器内的生物膜经历附着期、生长期和成熟期,在成熟期达到动态平衡状态;灌水器进水口处的生物膜附着快、生长速度快,生物膜最厚。脱落的生物膜沉积于流道内或出水口,体现流量的变化。灌水器的平均流量变化落后于生物膜的生长变化;当生物膜到达成熟期时,生物膜反复脱落生长,是灌水器堵塞的高风险期,表现为灌水器的平均流量持续下降。系统运行184 h后,可采用加酸、加氯等措施冲洗滴灌灌水器。     

滴头堵塞诱发过程及其可控方法的研究进展

滴头作为滴灌系统的关键部件,其性能的优劣直接反映了整个滴灌系统寿命、节水性及灌水的均匀性.流道的堵塞问题一直是抑止滴灌技术发展的主要瓶颈,而随着再生水滴灌、微咸水滴灌、雨水滴灌等技术的迅速发展,对滴灌系统抗堵塞能力也提出了更高的要求,堵塞问题成为了滴灌技术研究的热点.分析了滴头堵塞诱发的研究现状,就流道内的堵塞诱发因素、诱发过程、生物膜的存在对于堵塞的影响、流道内生物膜生物、物理特征以及控制方法等几个问题进行了探讨,并结合现代分子生物学技术及测量技术提出了有关流道内生物膜微生态多样性、生长特征等问题研究的发展方向.     

新型微压侧翼迷宫滴灌带设计方法研究

利用计算流体动力学(CFD)技术对设计的一种新型微压滴灌带的水力特性进行了数值模拟,得到了灌水器内部的压力和流速分布,预测了压力流量关系。研究结果表明:该滴灌带灌水器的流量系数为0.4858,说明流道内为全紊流状态,有利于灌水器的消能,并可提高其抗堵塞性;灌水器进口及出口的压力变化很小,流道内沿水流前进方向压力均匀下降,流道单元相同时,压力变化幅度相同;流道内的流速可分为流道齿尖附近的主流区及齿脚附近的旋流区二个区,每二个单元之间的速度分布基本一致。采用CFD技术进行微压滴灌带结构设计是一种新方法,可快速准确地获得灌水器的水力特性,为其结构设计提供理论指导,同时大大缩短了研制周期,降低开发成本。     

Water quality in drip/trickle irrigation: A review

Summary The intensive treatment of irrigation water required for the proper operation of drip irrigation systems is presently an accepted practice. To control emitter clogging, we need to know the basic causes of clogging. The major clogging factors have been identified and control measures developed to prevent emitter malfunction. All emitter clogging problems, however, have not been solved primarily because of cost. The main approach to control clogging is proper water treatment. The type of treatment is based on the quality of the irrigation water, which can be classified in terms of its physical, chemical and biological composition. The causes of emitter clogging and possible water treatment and preventive measures to maintain reliable operation are reviewed.     

温度对施肥滴灌系统滴头堵塞的影响

为探究不同灌水温度下水肥一体化滴灌滴头堵塞成因与过程,采用固定周期间歇滴灌的多因素完全随机试验设计方法,分别在冬、夏两个季节研究了3种不同泥沙级配浑水与3个不同施肥质量浓度组合对滴头堵塞的影响和堵塞变化过程。结果表明,灌水温度是影响滴头堵塞的重要因素,与水质交互耦合效应显著,夏季施肥和未施肥2种情况下灌溉滴头的抗堵塞性能均高于冬季,夏季有效灌水次数是冬季的1.26~1.43倍;施肥加速滴头堵塞的作用受泥沙级配和灌水温度的影响,冬季灌溉水中0.034~0.1 mm粒径粗颗粒含量越多,施肥质量浓度对堵塞的影响越敏感,夏季灌溉水中0~0.034 mm细颗粒越多,施肥质量浓度对堵塞的影响越敏感。建议灌水温度较低时,水肥一体化滴灌应控制在较低的施肥质量浓度下灌溉,适当增大次灌水时间,减少灌溉次数。     

不同冲洗措施下迷宫流道灌水器泥沙运行分布机理研究

评估了3种冲洗流速（0.25、0.50、0.75m/s）和5种冲洗频率（2d冲洗1次、4d冲洗1次、7d冲洗1次、10d冲洗1次和无冲洗对照组）对内嵌式齿形迷宫流道灌水器抗堵塞性能的影响,利用激光粒度仪对水源泥沙、滴头排出泥沙、滴头内滞留泥沙进行级配对比和粒径分析,并对不同冲洗处理下灌水器的相对流量和灌水均匀度进行拟合。结果表明：冲洗处理对齿形迷宫流道灌水器抗堵塞性能有显著影响,12种冲洗处理提高了内嵌式齿形迷宫流道灌水器的输沙能力,使滴头使用年限平均提高了39.58%;在冲洗作用下,泥沙凝聚沉降的机会降低,流道内小颗粒泥沙及时排出,没有形成体积较大的团聚体,滴头堵塞形成缓慢,灌水均匀度和流量系数下降缓慢;冲洗处理能有效减少毛管内泥沙堆积,降低大颗粒泥沙进入迷宫流道的机率,从而提高了齿形迷宫流道灌水器的抗堵塞性能。     

低压滴灌施肥条件下温度对滴头堵塞的影响

【目的】探究低压滴灌施肥条件下温度对滴头堵塞的影响。【方法】采用短周期间歇灌水试验方法,考虑温度、运行压力、肥料质量浓度等因素,展开完全随机试验,研究滴头堵塞过程,寻求适宜的加肥质量浓度阈值。【结果】温度越高、运行压力越大、加肥质量浓度越低滴头堵塞风险越小;温度40℃时,运行压力50kPa、加肥质量浓度3g/L的处理具有最高的平均相对流量、均匀度系数以及最低的堵塞率;不同温度下加肥质量浓度阈值不同,温度10、20、30、40℃时加肥质量浓度阈值分别为4、5、7和8g/L。【结论】升高温度、提高运行压力、降低加肥质量浓度能有效降低滴头堵塞风险;升高温度还能提高加肥质量浓度阈值及水流携带固体颗粒的能力,但升高温度对滴头堵塞风险的降低程度随着压力的升高而减弱。     

Trickle irrigation water quality and preventive maintenance

The most serious problem in trickle irrigation is clogging of emitters or applicators. Recommendations and guidelines are presented for preventive maintenance which include water filtration, chemical treatment, pipeline flushing, and field inspection. A suitable type, size, and capacity of a filtration unit is required. Chemical treatment should be considered in terms of theory and field research on the reclamation and prevention of emitter clogging. Proper procedures for the flushing and field inspection of trickle irrigation systems are also essential. Because water quality is of primary importance in the design and operation of this maintenance program, a tentative water-classification system was developed to establish criteria by evaluating the clogging potential of a trickle irrigation water source.     

Eight emitters clogging characteristics and its suitability under on-site reclaimed water drip irrigation

Drip irrigation is the most effective and reliable method for reclaimed water irrigation. The water usually contains a lot of suspended particles, metal salt ions, organisms and microbial communities, which will enhance the possibility of emitter clogging or more complex clogging mechanism. Emitter clogging has become one of  the key problems to the application and popularization of the drip irrigation technology. In this paper, we selected four kinds of pressure-compensating emitters and four kinds of non-pressure-compensating emitters, and executed the experiment of drip irrigation with on-site reclaimed water treated with cyclic activated sludge system (CASS). The emitter discharge ratio variation (Dra), coefficient of uniformity (CU) and clogging rate distribution were analyzed to evaluate the emitter clogging characteristics after eliminating the effect of temperature and pressure on the emitter outflow by data correction. The results showed that Dra and CU varied in three periods as system operation. The beginning of experiment was the fluctuated balance period, Dra and CU recurrent fluctuated in 5 %, and the emitters clogged at some spots after the system run 36–48 h. Then the two parameters varied linearly in 60–108 h, tuning into the initiate linear period, as the non-pressure-compensating emitters got an obvious linear change than the pressure-compensating ones with the gradient changed from ?0.094 to 0.042 and ?0.073 to 0.047, respectively. Some of the emitters have a significant difference on these two parameters at this stage. After the restarting in the second year, Dra and CU decreased sharply. The maximum decrement was, respectively, 9.6 and 10.7 %. Then they varied in line with a greater slope degree as all emitters reached the significant level, the gradient ranges were ?0.176 to 0.115 and ?0.216 to 0.117, respectively. This stage was called the accelerated linear period. Seriously clogged and completely clogged emitters appeared, and both Dra and CU dropped down to 38.7 and 41.5 %. Various degrees of clogged emitters often emerged in the end part of lateral at first then propelled to the head gradually, the completely clogged emitters in the end accounted for more than 73.0 % when the system run 540 h. Comprehensively considered, the pressure-compensating emitters and cusp-shaped saw-tooth non-pressure-compensating emitters with short flow path are recommended in reclaimed water drip irrigation. These researches are aimed to provide references explaining the emitter clogging mechanism of reclaimed water drip irrigation as well as its technological application and popularization.     

引黄滴灌水源中泥沙表面附生生物膜的分形特征

为了解决灌水器堵塞这个制约引黄滴灌技术应用和推广的关键问题,联合运用扫描电镜测试法和分形理论对黄河泥沙颗粒表面形貌进行了分析,结果表明:黄河泥沙颗粒表面形貌表现为以固体颗粒、微生物及其分泌的黏性胞外聚合物形成的复杂生物膜结构.黄河泥沙颗粒表面具有显著的分形和多重分形特征,简单分形维数虽然能从整体上表征颗粒物表面形貌的复杂性与不规则性,但未能刻画颗粒物局部奇异性的微观特征,而多重分形谱可以定量描述这种复杂泥沙颗粒形貌特征.黄河泥沙借助其巨大的表面积,吸附了大量的微生物,微生物分泌的胞外聚合物质量浓度高达276.08~360.68 mg/L,这就要求在控制引黄滴灌系统灌水器堵塞时,需要从以往单纯考虑泥沙颗粒物本身转变为综合考虑泥沙颗粒和微生物的耦合作用,寻求更为有效的堵塞控制策略.     

浑水特性与水温对滴头抗堵塞性能的影响

为探明迷宫流道滴头发生物理堵塞的成因及过程,采用分段粒径浑水周期间歇滴灌的试验方法,分别对含沙量、泥沙颗粒粒径和水温对滴头堵塞发生过程的影响进行研究。结果表明:对于泥沙颗粒粒径小于0.1 mm的浑水滴灌而言,粒径越小越易造成滴头堵塞,且其堵塞程度随浑水含沙量的升高而急剧升高;存在造成滴头堵塞的敏感粒径范围,在夏季灌溉时小于0.031 mm的粒径为易堵塞粒径;水温是影响滴头堵塞的重要因素,水温越高滴头的抗物理堵塞性能越好。     

Influence of fine particle size and concentration on the clogging of labyrinth emitters

The evolution of drip emitter clogging with labyrinth channel was investigated experimentally to study the fine particle size and concentration effects in the irrigation water. Short-term clogging tests were performed using muddy water containing particles with 8 different sizes (all less than 0.1 mm). The particles used in this study were composed of fine sands, slit and clay. Afterwards, verification tests were conducted to prove the results obtained from short-term clogging tests. The impacts of particle size and particle concentration in muddy water on emitter clogging were analyzed by means of calculating the mean discharge and the Christiansen uniformity coefficient. The results showed that for particles that were smaller than 0.1 mm in diameter, sediment concentration significantly affected clogging. The clogging level of emitters increased with raising the concentration. Especially when the sediment concentration was higher than 1.25 g/L, the impacts became remarkable. On the other hand, the sensitive sediment particle range that could get emitters clogged easily was found. In this study, the sensitive particle range were D6 (0.038–0.034 mm) and D7 (0.034–0.031 mm) The results aim to help in improving drip irrigation methods using water with high sediment concentration and providing experimental data for optimization design of emitter channel.