滴灌灌水器多类型流道的微压水力性能研究

微压条件下灌水器的水力性能相对于常压时会发生不同程度的变化。通过试验研究了八种灌水器在微压条件下的流态特征、出水均匀度及抗堵塞性能。结果表明,非压力补偿式滴灌产品在微压和常压下的流量变化率没有明显波动,清水下出水均匀性良好,而抗堵塞性能较差;压力补偿式滴头因为在微压下存在启动水压而影响了工作状态,当超过启动水压后其出水均匀性与常压时没有明显变化,抗堵塞性能良好,但是流量随压力增大而增大,没有起到压力补偿作用。     

振动水压下滴灌灌水器水力性能研究

传统的滴灌系统大都是在恒定水压下工作,其核心元件灌水器容易发生堵塞。以由绕流流道单元构成的灌水器为研究对象,通过计算机CFD模拟和实验来研究灌水器在振动水压下的水力性能。振动模式分别选取为梯形波形、正弦波形、三角波形和矩形波形,取基础水压、振动周期和振动幅度3个参数来设计正交试验。研究结果表明,CFD模拟数据和实验数据具有比较高的一致性;灌水器在振动模式下的消能效果和水流波动效应优于恒压下的状态;基础水压对等效水压的影响最为显著。通过对模拟数据进行线性回归,建立了基于振动参数的等效水压计算表达式,为计算灌水器等效水压值提供了一定的参考。     

高频脉冲条件下灌水器水沙两相流数值模拟

为提高灌水器的抗堵塞性能,在与射流三通产生波形相同参数(周期、振幅)的高频脉冲波(正弦波、三角波、梯形波、矩形波)的条件下,以迷宫流道灌水器为研究对象,应用CFD两相流含沙量数值分析,采用k-ε湍流模型及多相流Eulerian模型,模拟高频脉冲条件下流量与压力水头关系、含沙量的瞬时分布,分析高频脉冲条件对颗粒物沉积区含沙量变化的影响。结果表明,高频脉冲波对灌水器平均流量和抗堵塞性能影响较大,高频脉冲波的波动性和连续性对提高灌水器抗堵塞能力起主要作用;抗堵塞能力由大到小的高频脉冲波形顺序为正弦波、三角波、梯形波、矩形波;入流含沙量增加会导致旋涡区泥沙的沉积,高频脉冲波可以增强旋涡区的冲刷以提高抗堵塞性能;灌水器内各处含沙量均随颗粒粒径的增大而升高,不同粒径下含沙量分布和变化略有不同。射流三通产生的脉冲波有利于提高灌水器的抗堵塞能力。     

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。     

移动插入式灌水器的结构研究与抗

通过对现有滴头、滴箭等产品结构的研究、改进与优化,设计开发出一种抗堵塞功能较强的插入式地下灌水器产品,整体上具有快速装拆、移动灵活、滴流量偏差小、水力性能稳定等特点。为检验其抗堵塞功能的优劣,分别进行了自由出流和插地出流条件的滴水试验。结果表明：移动插入式灌水器出流均匀,具有较强的抗堵塞性能,自由出流时的平均滴水量与多次间歇式插地出流时的平均滴水量相当,其波动范围在5％以内,较适合于在移动式地下滴灌系统中应用。     

含沙水滴灌条件下灌水器抗堵塞试验研究

对4种不同滴灌管(带)在含沙水滴灌条件下灌水器的出流量变化及淤积堵塞情况进行了田间试验研究。经过多次灌水试验,结果表明,4种滴灌管(带)灌水器出流量均随灌水次数的增加和距离毛管进水口长度的增加呈减小趋势,最后完全堵塞的灌水器均发生在毛管的末端;在相同水质和灌水压力下,大流量灌水器抗堵塞性能较好,即大流道灌水器的抗堵塞性能优于小流道灌水器;随着灌水次数的增加在滴灌管(带)的管腔内有细小泥沙淤积,小流量滴灌管(带)在70～80 m处泥沙淤积量骤然增加,大流量滴灌管(带)在80～90 m处骤然增加,管内泥沙的沉积大大增加了灌水器的堵塞几率,因此定期对滴灌带进行冲洗可以有效减小堵塞。     

微灌系统有限元法水力解析和设计(二)

2．3均匀坡度上毛管的设计2．3．1单向毛管的设计伊塔耶和阮科（YitayewandWaxrick,1988）及哈索特等人（Hathootet,1993）提出了一个用于设计毛管的设计方法,在一条单向毛管的内径和长度中的一个参数、用户要求的平均灌水器流量和灌水均匀度给定的条件下,另外一个未知参数和所需要的毛管操作压力就可以准确地设计出来,这个方法的设计步骤为：第一步给设计参数选定由小到大的一组值;第二步对每一个选定的值,找出其能产生用户要求的平均灌水器流量qreq的毛管操作压,并评价出灌水均匀度;第三步画出灌水均匀度与设计参数及毛管操作…     

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。     

硬水灌溉陶瓷灌水器堵塞特性研究

受水资源短缺的限制,我国仍有较多地区采用硬水进行灌溉。硬水易引发灌水器堵塞,为探明硬水灌溉下水的硬度对陶瓷灌水器堵塞的规律及堵塞机理,选取砂基陶瓷灌水器,使用杨凌自来水和配制的3种不同总硬度的硬水进行灌溉实验,观察其在55 d内流量变化过程,观察灌水器内堵塞物质形态,并借助X射线衍射仪检测堵塞物成分、含量。结果表明:硬水会造成灌水器堵塞,且水质越硬,堵塞越严重;硬水灌溉条件下,陶瓷灌水器流量随时间的变化过程分为"波动阶段"和"下降阶段",且水质越硬,流量下降越明显;堵塞物质分析表明CaCO_3沉淀是灌水器堵塞的主要原因。堵塞物影像表明,运行时间越长,水质越硬,堵塞物沉积越严重。研究结果为陶瓷灌水器在水质较硬地区的推广提供了参考。     

迷宫流道转角对灌水器抗堵塞性能的影

以转角分别为45.0°、60.0°、67.5°和75.0°的齿形流道灌水器为研究对象,应用CFD流场速度数值分析、PIV颗粒运动轨迹线和速度观测对比以及浑水抗堵塞测试相结合的方法,研究了转角对灌水器水力性能和抗堵塞能力的影响.结果表明转角与流量系数及流态指数均呈负相关关系,而灌水器的抗堵塞能力随着转角的增加呈下降趋势.综合分析转角对水力性能和抗堵塞性能的影响,提出迷宫流道结构灌水器的合理转角为60.0°.     

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。     

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.     

新型微压滴灌灌水器水力性能试验研究

在试验室内,对研制的微压灌水器进行了水力性能试验。试验结果表明:在微压(2~5 m)工作时,新型微压滴灌灌水器在自由出流状态下的出流规律符合设计要求;在工作压力范围内,微压灌水器的流量稳定,变化小;新型微压滴灌灌水器在连续工作1周后流量略有变化,出流更加均匀;微压滴灌灌水器抗堵塞能力强,性能可靠。     

温室水肥滴灌系统迷宫式灌水器堵塞试验

为探明温室滴灌灌水器堵塞的影响因素及机理,研究了灌水量和施肥量对灌水器堵塞的影响,并利用场发射扫描电镜分析了灌水器内的堵塞物质。结果表明,灌水器平均流量随着灌水量和施肥量的增加呈下降趋势,下降幅度在1.51%~14.16%之间。方差分析表明施肥量对灌水器平均流量的影响达到极显著水平(P0.01)。解剖灌水器后发现堵塞物质多沉积在流道前部。堵塞物质主要由生料带残渣、微小沙粒和白色粉末状化学沉淀物组成,其中白色粉末主要由钙、镁、碳、氧、磷元素等组成。说明本试验中灌水器堵塞主要是由物理堵塞和化学堵塞共同作用引起的。     

Effect of flushing frequency on emitter clogging in microirrigation with effluents

Flushing is an important maintenance task that removes accumulated particles in microirrigation laterals that can help to reduce clogging problems. The effect of three dripline flushing frequency treatments (no flushing, one flushing at the end of each irrigation period, and a monthly flushing during the irrigation period) was studied in surface and subsurface drip irrigation systems that operated using a wastewater treatment plant effluent for three irrigation periods of 540 h each. The irrigation systems had two different emitters, one pressure compensating and the other not, both molded and welded onto the interior dripline wall, placed in laterals 87 m long. Dripline flow of the pressure compensating emitter increased 8% over time, while in the nonpressure compensating emitter, dripline flow increased 25% in the surface driplines and decreased 3% in the subsurface driplines by the emitter clogging. Emitter clogging was affected primarily by the interactions between emitter location, emitter type, and flushing frequency treatment. The number of completely clogged emitters was affected by the interaction between irrigation system and emitter type. There was an average of 3.7% less totally clogged emitters in flushed surface driplines with the pressure compensating emitter as compared to flushed subsurface laterals with the nonpressure compensating emitter.     

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。     

Emitter discharge variability of subsurface drip irrigation in uniform soils: effect on water-application uniformity

Emitter discharge of subsurface drip irrigation (SDI) decreases as a result of the overpressure in the soil water at the discharge orifice. In this paper, the variation in dripper discharge in SDI laterals is studied. First, the emitter coefficient of flow variation CV _q was measured in laboratory experiments with drippers of 2 and 4 L/h that were laid both on the soil and beneath it. Additionally, the soil pressure coefficient of variation CV _hs was measured in buried emitters. Then, the irrigation uniformity was simulated in SDI and surface irrigation laterals under the same operating conditions and uniform soils; sandy and loamy. CV _q was similar for the compensating models of both the surface and subsurface emitters. However, CV _q decreased for the 2-L/h non-compensating model in the loamy soil. This shows a possible self-regulation of non-compensating emitter discharge in SDI, due to the interaction between effects of emitter discharge and soil pressure. This resulted in the irrigation uniformity of SDI non-compensating emitters to be greater than surface drip irrigation. The uniformity with pressure-compensating emitters would be similar in both cases, provided the overpressures in SDI are less than or equal to the compensation range lower limit.