Sprinkler rotation and water application rate for the newly-designed complete fluidic sprinkler and impact sprinkler

One important indicator of the good performance of rotating sprinklers is the uniformity of rotation.The objective of this experimental study was to investigate the rotation uniformity and water application rate of the newly designed complete fluidic sprinkler in comparison to the widely used impact sprinkler,with the goal to offer recommendations to improve the fluidic sprinkler’s operation performance.Single-sprinkler water application experiments were conducted in accordance with the American Society of Agricultural and Biological Engineers standard.Sprinkler completion time through the four quadrants of rotation and water delivery in catch cans were measured at different operating pressures for each sprinkler-nozzle size configuration.The capabilities of Matrix Laboratory were employed to simulate the overlap of adjacent quadrants and to visualize the effect of sprinkler rotation speed variation on water application rate.Quadrant completion time variations were small for both impact and fluidic sprinklers.However,variations in completion time through the quadrants were higher for the fluidic sprinkler compared to the impact sprinkler.Relatively higher variations in water application rates were also observed for the fluidic sprinkler.The optimization of the design features of the fluidic component is necessary to improve rotation stability and to minimize variability in water application rate of the fluidic sprinkler.The study significantly highlighted some performance qualities of the complete fluidic sprinkler in comparison to that of the impact sprinkler.The findings of this research will help to improve the efficiency of the new type complete fluidic sprinkler.

Comparison of droplet distributions from fluidic and impact sprinklers

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.

Hydraulic performance characteristics of impact sprinkler with a fixed water dispersion device

One way to adapt to the trend towards low-energy and to improve the hydraulic performance of the impact sprinkler under a low pressure condition is by means of a fixed water dispersion device.A fixed dispersion device disperses jet flow from the nozzle continuously.The shape of the tip,impact angle(θ),diameter(D),and depth in the jet flow(d)have significant influence on the hydraulic performance.In this study,the hydraulic performance characteristics of impact sprinkler as affected by the fixed water dispersion device were studied under indoor conditions.Radial water distributions from the sprinkler were obtained by experiments for the fixed water dispersion devices.MATLAB was used to transform the radial data into net data,and the uniformities were simulated in a square layout from 1 to 2 times the range(R).The droplet size distributions from the fixed water dispersion devices were measured by a laser precipitation monitor(LPM).Results showed that the range increased with the increase of pressure,and the sprinkler with type C_(2) produced a rectangular-shaped water distribution pattern,while the range was maintained.A maximum uniformity of 71.56%,75.56%,77.23%,73.32%,78.88%and 86.67%was found for types A1,B1,C1,A2,B2,and C_(2),respectively under a pressure of 200 kPa.The uniformity from the sprinkler using type C_(2) surpassed 80%,while type C1 fell below.Droplet sizes from type C_(2) was best,and the mean droplet diameter decreased with the increase of pressure.Hence,type C_(2) can be selected for further optimization of the design features to improve the hydraulic performance of the impact sprinkler under low pressure conditions.

Range formula based on angle of dispersion and nozzle configuration from an impact sprinkler

Jet breakup and dispersion from impact sprinkler are mainly influenced by the configurations of nozzle and dispersion device.Based on the structure,different types of nozzles were designed and tested with a pointed tip dispersion device under low pressure conditions.Experiments were performed using High-Speed Photographic technique,and Matlab computation program was established and applied to determine the initial jet breakup length and angle of dispersion from the nozzles.The sprinkler range decreased with the increase in diameter of nozzle,and the largest range of 15.1 m was produced from sprinkler with 6 mm nozzle size under a pressure of 150 kPa.The angle of dispersion decreased with the increase of jet velocity,the spray coverage from sprinkler with 6 mm nozzle size was 1478 mm under 150 kPa,and was not statistically different when the pressure was increased.A new range formula was established for sprinkler with dispersion device through curve fitting of the parameters of initial jet breakup length,angle of dispersion,nozzle size and working pressure.The new formula was reliable for calculating range with a relative error less than 3%.Since the formula is based on the angle of dispersion,it could be useful to estimate uniformity of water distribution in sprinkler irrigated fields.

养殖肥水喷灌条件下摇臂式喷头水力性能研究

【目的】研究不同喷灌介质对喷头水力性能的影响。【方法】以20PY2H摇臂式喷头为研究对象,在不同工作压力下测定了清水和养殖肥水2种喷灌介质对喷头压力-流量、喷头水量分布的影响。通过模拟计算和田间喷灌试验分析相结合的方法,探查喷灌介质、工作压力、组合间距、田间气象条件与喷灌均匀性之间的关系。【结果】(1)与清水灌溉相比,养殖肥水运行下喷头流量降低了2.06%~5.38%,射程前中段径向水量分布差异较大;(2)工作压力为200~300k Pa、组合间距为1.0R~1.4R条件下,MATLAB拟合出的CU模拟值为0.74~0.88,CU试验值为0.66~0.79。复杂的大田气象条件导致喷灌均匀系数下降了6.28%~12.78%。工作压力、喷头组合间距对清水运行喷灌均匀性的影响大于养殖肥水运行。【结论】养殖肥水喷灌更利于喷灌系统降低工作压力和增加喷头布置间距以降低设计成本。

某钨矿基于预选抛废作业的洗矿优化试验及生产实践

采用XNDT-104全自动智能在线分选机,使用X射线光电选矿技术对某钨矿石进行预先抛废,抛废尾矿品位为0.035%,作业抛废率45.07%,精矿品位由0.228%富集到0.293%,金属回收率达到92.18%,预抛废效果明显。但在处理堆存时间长、矿石表面性质发生变化、泥化程度高、含粉矿多的低品位白钨矿时,抛废指标大幅下降,抛废率下降到43.86%,抛废尾矿品位提高到0.046%,金属回收率也下降到90.28%。经分析主要是该矿粉矿较多,易黏附在矿石表面,影响分选机的识别效果;同时因粉矿品位较高,附在废石表面会造成废石品位偏高,影响金属回收率。为解决粉矿问题,采取入选前洗矿作业,后又对喷水装置等进行工艺改进,试验结果表明入选物料洗矿越彻底,取得的指标越优。最终试验结果:抛废尾矿品位降至0.026%,作业抛废率达53.29%,精矿品位由0.206%富集到0.412%,金属回收率达到93.298%的优良指标。

我国摇臂式喷头的研究与发展

综述了国内外摇臂式喷头的发展历程和未来趋势,详细分析了近期摇臂式喷头的新型结构与适用特点,结合我国实际情况论述了我国在摇臂式喷头的研究与生产中存在的研究手段单一、研究力量单薄、企业缺乏产业化等问题,提出要应用新发展的计算流体动力学(CFD)、计算结构动力学(CSD)和粒子成像速度场仪(PIV)等技术进行喷头基础理论研究,加强联合攻关,建立质量监督体系等发展摇臂式喷头的对策和建议。

摇臂式喷头组合喷洒均匀性的改进

该文针对摇臂式喷头副喷嘴为圆形,径向水量分布中部较高不利于组合的问题,根据水射流原理,设计出一种新型结构的副喷嘴,其上端设有盖板,起到阻挡水流的作用,使副喷嘴水流射出后主要分散在近处,从而有利于提高组合喷洒的均匀性。分别对15PY、20PY、30PY摇臂式喷头副喷嘴改进前后的水量分布进行了对比试验,同时,以正方形布置方式为例,计算出不同组合间距下的喷洒匀性系数。结果表明:副喷嘴的改进消除了改进前喷头中间部分水量,使径向水量分布呈"三角形"。改进副喷嘴后提高了均匀性系数,不同组合间距下的值均为80%以上,平均喷灌强度符合喷灌规范中的要求。最后,提出副喷嘴改进后15PY,20PY,30PY摇臂式喷头的最佳组合间距分别为1.2R,1.3R,1.1R,计算出组合均匀性系数值分别为85.6%,86.3%,85.3%。改进后的副喷嘴对喷洒均匀性有较好的改善作用。

异形喷嘴对变量喷头水力性能的影响

研究了异形喷嘴对变量喷头水量分布的影响。依据面积相同原则设计多种形状的异形喷嘴,测量了异形喷嘴的流量系数、射程和末端水滴直径,得出星形喷嘴射程降低较少,不同压力时水量分布规律相近,可改善低压力下均匀度。对比了星形喷嘴变量喷头和圆形喷嘴变量喷头的水力性能,星形喷嘴变量喷头远射程处平均喷灌强度为近射程处的85%,圆形喷嘴变量喷头远射程处平均喷灌强度为近射程处的79%,星形喷嘴变量喷头水量分布优于圆形喷嘴变量喷头。分析比较了变量喷头水量分布等值线图,结果表明,星形喷嘴变量喷头的水量分布均匀度好于圆形喷嘴变量喷头,方形喷洒域的均匀度好于三角形喷洒域。

摇臂式喷头内流道流动分析与数值模拟

应用CFD通用软件Fluent模拟了PY140型摇臂式喷头的内流道在安装两种常用稳流器和不安装稳流器情况下的三维黏性流场,分析了三种稳流器情况下喷头流量、内流道静压力分布以及出口断面平均湍动能随进口工作压力的变化规律,并进行了试验验证。研究结果表明不同进口工作压力下喷头流量的计算值要高于实测值约11%,但两者的变化趋势非常一致。喷头安装稳流器有助于消除内流道中的涡流和横向流,降低喷头出口湍动能值,但在一定程度会增加内流道阻力损失,影响喷头的过流能力。此外,常用的90°出口扩散角的圆锥形喷嘴容易在喷嘴出口附近产生逆流。数值模拟和试验表明,减少喷嘴出口扩散角可改善喷嘴出口流态,提高喷头流量。

摇臂式喷头副喷嘴仰角及位置参数的优化

摇臂式喷头副喷嘴的主要作用是增加喷头近处的喷水量，从而提高喷头的喷灌均匀度，因此对摇臂式喷头副喷嘴的研究具有重要意义。该文采用流场模拟和试验相结合的方法对摇臂式喷头的副喷嘴结构参数进行了优化设计。首先采用逆向工程的设计方法，运用Pro/E建立了摇臂式喷头的三维结构，选择副喷嘴的仰角和位置为待优化参数，设计出9种副喷嘴结构的摇臂式喷头。运用Pro/E和HyperMesh软件建立了9种副喷嘴结构摇臂式喷头的三维内流道模型，利用CFD软件FLUENT对9种喷头的内流道进行三维模拟，运用快速成型技术加工出喷头样品进行试验验证，在矩形组合方式下运用4种插值方法（距离插值法、线性插值法、立方插值法和三次样条插值法）计算喷灌组合均匀度，并且利用Sprinkler3D 软件通过二维插值的方法建立了9种喷头的压力水量分布模型，对喷头喷洒均匀性进行评价。结果表明，6号喷头（副喷嘴位置参数为19.8 mm、仰角参数为18°）的模拟流量和速率较大，试验水量分布在2～12 m之间能够保持较好均匀性，且射程达到14 m以上，喷灌均匀度在压力为250和300 kPa下都达到80%以上。因此，副喷嘴位置参数19.8 mm、仰角参数18°为摇臂式喷头副喷嘴的最佳结构参数。该研究为摇臂式喷头结构设计和喷灌系统优化等提供参考。

摇臂式喷头与全射流喷头水滴分布对比试验

摇臂式喷头(impact sprinkler,PY)出口流体为单相水,全射流喷头(complete fluidic sprinkler,PXH)出口流体为气液两相流,为了深入探索2种类型喷头水滴分布的存在规律及差别,该文采用激光雨滴谱仪测量技术对PY及PXH喷头的水滴分布进行试验研究,采用体积加权法分析了这2种喷头在工作压力为150、200、250、300和350 k Pa情况下,距喷头不同距离处的水滴频率分布、水滴累计频率及中数直径的变化规律。结果表明:1)PXH喷头水滴频率普遍小于PY喷头。PXH喷头和PY喷头水滴频率分布分别符合对数正态分布和正态分布;2)PXH喷头水滴累计频率变化更加均匀,2种喷头的水滴直径分布均符合指数函数分布规律,在距离喷头距离较小时,PXH喷头比PY喷头的拟合精度更高,在距喷头距离为4 m下,PXH喷头拟合函数的R2值较PY喷头高3.5%;3)在低压条件下距喷头不同距离时,PXH喷头的水滴分布更加连续及均匀。建立了2种喷头中数直径与工作压力及距喷头距离的函数。该结果完善了多类型喷头喷洒水力学特性,对研究射流运动模型及喷洒的外特性提供了参考。

基于LPM的摇臂式喷头水滴分布试验研究

为了研究旋转式喷头水滴直径、速度及动能的分布规律,采用激光雨滴谱仪(Laser Precipitation Monitor,LPM)对3026B型摇臂式喷头分别在0.15,0.20,0.25,0.30,0.35 MPa这5种工作压力下进行了室内无风水滴分布试验,并根据最小二乘法原理建立了水滴分布数学模型.试验结果表明:3026B型摇臂式喷头的喷洒水滴直径与喷头距离之间总体上呈指数函数分布;直径为1~3 mm的水滴在5种压力下占整个喷洒区域的频率分别为56.80%,64.35%,72.14%,61.72%,40.17%;距喷头不同距离的水滴累积频率曲线斜率随着压力的增加逐渐减小;水滴速度与直径呈对数函数分布;水滴动能与喷头距离呈指数函数分布,其相关系数在0.800以上.压力对近处水滴直径、速度及动能的分布规律影响较小,对远处的影响较大.

弹尾形稳流器对摇臂式喷头内流道水力性能影响

对PY140型摇臂式喷头在不同的弹尾形稳流器与喷嘴直径组合工况下进行了喷头内流道水力性能试验。结果表明:喷头内流道阻力损失与喷嘴直径、稳流器长度及进口工作压力呈正比,并建立了回归模型;喷管段产生的阻力损失与喷头内流道阻力损失之比的平均值为0.666;当进口工作压力一定时,喷嘴工作压力与喷嘴直径、稳流器长度呈反比,喷头流量的最大相对误差为4.7%;锥角为40°的圆锥形喷嘴流量系数算术平均值是0.928。

考虑配重的垂直摇臂式喷头摇臂运动规律及水力性能

为了研究摇臂运动规律及配重对喷头水力性能的影响，以垂直摇臂式喷头为研究对象，对垂直摇臂式喷头摇臂的运动特征进行理论分析，推导出摇臂运动周期公式，并在公式中考虑了配重位置变化因素；采用高速摄影对 Nelson SR100喷头的摇臂运动情况进行了试验研究，将得出的摇臂运动周期与计算结果进行对比，并通过改变配重安装位置来考察运动周期变化对喷头水力性能的影响。结果表明：通过高速摄影试验得到的摇臂运动周期与理论公式计算值吻合较好，相对误差基本在10%以内，验证了推导公式的正确性，针对理论公式的计算误差，根据试验结果对理论进行了修正，进一步提高了理论公式的计算精度，相对误差都在3%以内；增大喷头工作压力和前移配重安装位置均可使喷头的运动周期减小。配重位置距摇臂旋转轴较近时，喷头近处的喷灌强度明显增加，3～10 m内的水量分布较配重在最远处时增加了40%左右；配重位置距摇臂旋转轴远时，喷头近处的喷灌强度随之降低，射程末端的喷灌强度随之增加。该研究可为垂直摇臂式喷头摇臂设计方法的建立和在喷头运行过程中能合理调节摇臂配重提供参考。

隙控式全射流喷头性能特点及与摇臂式喷头的比较研究

研制了一种新型旋转式喷头——隙控式全射流喷头,介绍了其结构形式及工作原理。首次对二种PX 10型号的全射流喷头及一种PY 210摇臂式喷头的水力性能进行了对比试验及分析。研究表明:隙控式全射流喷头的流量大于试验用PY 2摇臂式喷头8%左右,射程比摇臂式喷头的射程明显加大,最大增幅达到31%。全射流喷头水量分布均匀性与摇臂式喷头相当,但末端雨滴直径小于摇臂式喷头。由于其独特的射流元件及反向机构,全射流喷头结构简单,性能优良,价格低廉,具有显著的节能效果及良好的市场前景。

出口可调式变量喷头喷灌均匀性

以喷洒域形状和水量分布均匀性为指标研究变量喷头的喷灌均匀性,分析了影响PY2系列喷头射程和水量分布的关键因素,得知改变单一参数的变量喷头喷灌均匀性较差.为提高变量喷头的灌溉均匀性,设计了出口可调式的变喷洒域喷头,使用流量调节机构改变喷头工作压力,使用出口调节机构改变喷头出口面积,通过出口面积和喷头工作压力的同步调节实现均匀喷洒.测试了出口可调式变量喷头的水力性能,对比了圆形喷嘴变量喷头和出口可调式变量喷头水量分布,出口可调式变量喷头不同射程处喷灌强度相近,喷洒性能优于圆形喷嘴变量喷头.计算了变量喷头的方形喷洒域系数和不同间距下的组合灌溉均匀性,结果显示BPY20变量喷头的方形喷洒域系数为97.8%,最佳组合间距为1.66,组合灌溉均匀性为75.4%;BPY30变量喷头的方形喷洒域系数为91.5%,最佳组合间距为1.69,组合灌溉均匀性为77.2%.

SR100垂直摇臂式喷头摇臂有限元分析

针对垂直摇臂式喷头导流器几何结构及运动特性,研究了摇臂在运动过程中的受力及约束情况,并结合动力学理论计算公式,计算和分析了喷头在运动过程中载荷大小和约束情况.采用ANSYS Workbench软件,建立摇臂三维模型,对摇臂进行有限元模态分析、静力学分析及疲劳可靠性分析.通过有限元模态分析,得出各阶模态下摇臂的固有频率和振型,该摇臂的各阶振型主要表现为弯曲、扭曲及局部变形;当摇臂的工作频率小于41.785 Hz时,其振动以一阶振型为主.通过静力分析得出摇臂的应力分布情况,发现在摇臂安装导流器处存在较大的应力分布;通过对摇臂的疲劳分析,发现摇臂各部位安全系数差别很大,其最小值位于摇臂前端,为1.229 1,长期工作此处易发生裂纹或断裂.为提高摇臂的工作稳定性与可靠性,可以通过加强薄弱部位设计,或改进局部结构、提高材料的力学性能来实现.

全射流喷头与摇臂式喷头的对比实验

提出臂式喷头和全射流喷头的计算公式,通过实验对比它们的参数。结果表明,全射流喷头步进角度和步进频率主要由导管长度决定,导管越长则步进角度越大,步进频率越小。对于臂式喷头,它的步进角度和步进频率的可改变幅度不大,因此全射流喷头具有一定优越性。提出了全射流喷头步进角度与管长之间的关系式,左右压差与导管长度和工作压力的经验公式。

低压条件下PY_115型摇臂式喷头水力性能试验

针对喷头在低压条件下工作时水力性能较差的问题,提出采用异形喷嘴降低水滴打击强度并改善喷洒均匀性的方法。选取PY115型摇臂式喷头为研究对象,设计了3套改进喷嘴的方案,在出口喷嘴上增加了1、2、3个凹槽,凹槽的尺寸均为宽0.5 mm,高0.3 mm,位置分别在出口喷嘴下方和左右两侧。在工作压力为200 kPa下进行了试验测量,同时在正方形组合间距为13～18 m时,采用Matlab语言编制程序对其进行了仿真计算。试验和计算结果表明:在低压条件工作时,随着凹槽数量的增多,流量增大,射程缩短8.1%～9.4%,末端水滴直径降低系数为2.9%～6.8%,平均喷灌强度增大并均符合规范要求。增加凹槽有利于提高组合均匀系数,出口喷嘴增加3个凹槽时效果最佳,组合均匀系数最高超过90%,证明了所设计异形喷嘴方案的可行性。