平移式喷灌机组行走速率对喷灌均匀性影响

为研究低压喷灌下喷灌机行、止速率比的合理取值,以自行研制的轻小型移动式喷灌机组为研究对象,通过室内组合喷头试验,探究行、止速率比与喷灌均匀性和喷灌强度的关系。通过spss软件进行方差分析,并采用多重比较分析法,进行差异显著性分析。结果表明:在工作压力为0.07 MPa情况下,行、止速率比对喷灌均匀性系数没有显著性影响,对喷灌强度具有显著性影响。当行、止速率比为45%时,喷灌均匀性系数在85%以上,同时喷灌强度为20.5mm/h,增大行、止速率比可小幅度的增大喷灌强度,60%的行、止速率比下喷灌强度为21.1mm/h,在90%时略有下降,达到19.97mm/h。喷灌强度基本趋于一致,可满足喷灌要求。     

行喷式喷灌机喷灌强度和均匀度的计算

本文根据国外机组引进课题以及几次喷灌机设计计算的总结与研究,说明并推求出时针式喷灌机和平移式喷灌机喷灌强度和均匀度的计算公式,且提出了喷头水量分布的模拟计算方法。文章主要解决了行喷式喷灌机的喷灌强度和均匀度的计算问题。     

电动平移式喷灌机的行走同步控制与仿真研究

在传统试验中,大型平移式喷灌机在操作的过程中会受到很多因素限制,导致浪费的情况十分普遍。文章主要对电动平移喷灌机行走同步控制与仿真进行了研究,并对此作出了深入探讨,提出见解,对今后的研究具有一定的参考意义。     

喷灌条件下土壤水分分布的数值模拟研究

现有试验研究结果表明,喷灌水量在土壤中的分布比其在地面的分布要均匀得多。通过建立三维土壤水分运动数学模型来模拟喷灌条件下土壤水分运动情况,并用经济解法对方程进行求解。使用编制的程序进行实例计算的结果表明,喷灌水量在土壤中的分布要比在地表的分布均匀得多。喷灌水量在土壤中分布的均匀性与初始的土壤水分分布均匀性有较大的关系。     

太阳能平移式喷灌机行走驱动系统配置与性能研究

对太阳能平移式喷灌机的行走驱动系统进行方案设计与理论计算,比较不同工况下喷灌机行走所需驱动功率,确定机组在不同工况下的驱动电机选型与光伏配置。该研究以一日累计作业时间为太阳能驱动平移式喷灌机的技术评价指标,预测陕西关中及宁夏地区晴天和阴天或雾霾天气下的机组续航能力;并得到各工况下喷灌机行走速度和行走坡度与一日累计工作时间的关系:一日累计作业时间随机组运行速度的提高与爬坡角度的增大而降低;相同工况下,晴天一日累计作业时间为阴天或雾霾天气的1.5倍。研究结果表明,以独立光伏发电系统作为平移式喷灌机的驱动能源是可行的,能够满足机组日常行走作业的需求。该研究结果可为太阳能平移式喷灌机行走驱动系统方案设计提供参考。     

影响电动圆形喷灌机灌水均匀度的因素及分析

通过对电动圆形喷灌机工作原理介绍,研究了影响其灌水均匀性的主要因素,并对这些因素进行分析,及相关数学推导,找到影响机组灌水均匀性的机理,进而提出相关的改进措施和注意事项。为设计人员提高机组的灌水均匀性提供理论依据。     

喷灌机的选购与使用

喷灌机是一种将动力机、泵、管路、喷头和移动装置等设施,按喷灌方式组合配套成具有整体性的喷灌设备,将压力水喷射到低空,经雾化后像雨滴一样均匀地降落到作物和地表面。常用的喷灌机有小型喷灌机、大型喷灌机、平移式喷灌机、移动式喷灌机、卷盘式喷灌机、指针式喷灌机、中心支轴喷灌机、圆形喷     

滚移式喷灌机压力对喷灌均匀性影响

为解决喷灌机械的喷灌均匀性差、移动不方便等问题,研制一种操控简单、适应性强的大型滚移式喷灌机,对其水量分布均匀系数和喷灌强度进行试验.试验采用单因素多重比较设计方法,选取距进水端距离分别为40,150,260 m处为测试处,喷灌压力分别为0.20,0.25,0.30,0.35,0.40 MPa,并运用Design-expert软件进行分析,研究各喷灌压力在各测试处对水量分布均匀系数和喷灌强度的影响.结果表明,各测试处的压力对水量分布均匀系数的影响均为显著性差异,且随喷灌压力上升,水量分布均匀系数升高.对喷灌强度的影响呈正相关性,但喷灌压力高于0.30 MPa时影响不显著.喷灌压力在0.40 MPa时,水量分布均匀系数平均可达88.75%,喷灌强度为12.3 mm/h,各处的水量分布均匀系数和喷灌强度能够保持均匀一致,并能够稳定作业,达到最优状态,完全满足大型滚移式喷灌机的性能要求.该项研究对于促进滚移式喷灌机推广和应用具有重要意义,为其深入研究提供了参考依据.     

基于正交试验法下对喷灌均匀性影响因子的综合分析

为了优化轻小型平移式喷灌机组灌溉施肥工况,在喷灌工作压力为0.25 MPa,比例吸肥泵进出口压力为0.22 MPa情况下,设计正交试验以研究施肥浓度、喷头车行走速度和喷灌高度3个因素对轻小型平移式喷灌机组水肥一体化性能的影响;对试验结果进行极差分析和方差分析,获得三因素的最佳水平组合并对比三因素影响因子大小.试验结果表明：影响轻小型平移式喷灌机组肥液浓度均匀度(CU₁)及肥液浓度分布均匀度(DU₁)的主要影响因素是喷灌高度,而施肥浓度和行走速度对其影响较小,显著性均大于0.05.影响肥液质量均匀度(CU₂)最主要因素是喷头车行走速度,其次是喷灌高度,而施肥浓度对其影响不具有统计学意义.施肥浓度、喷灌高度和行走速度对肥液质量分布均匀度(DU₂)影响因子显著性均大于0.05.最优施肥技术水平组合为A1B2C2,即施肥浓度为0.4 g/L,喷灌高度为1.2 m,行走速度为30 m/h.     

射流脉冲三通毛管灌水均匀性试验研究

为了提高低压滴灌系统灌水均匀性,基于附壁与切换原理发明了射流脉冲三通发生器,试验研究了不同压力工况下脉冲频率、脉冲振幅2种因素对灌水均匀系数、流量偏差率的影响,并分析了脉冲条件下毛管铺设长度和进口压力对灌水均匀性的影响.结果表明:在毛管铺设长度相同时,不同低压下射流脉冲三通灌水均匀系数的平均值比普通三通提高了0.65%,流量偏差率明显低于普通三通,平均降幅为3.62%;低压条件下产生脉冲频率高于200次/min,脉冲振幅高于2.5 m;相同压力条件下,灌水均匀系数随毛管铺设长度的增大而降低,流量偏差率随毛管铺设长度的增大而显著增大;毛管铺设长度相同时,灌水器流量随进口压力增大而增大,进口流量也会随之增大.     

滚移式喷灌机关键部件的设计与试验

针对节水灌溉技术中存在自主研发能力弱、技术性能低、设备可靠性差、经济成本过高等问题,设计研制出一种节省材料、降低油耗、工作可靠、喷灌均匀度高的滚移式喷灌机.根据输水支管受力特点,通过Matlab对支管壁厚进行优化设计,优化出3种不同壁厚的输水支管,不仅能够节省材料,降低油耗,还能增加机组爬坡能力.对滚移式喷灌机的自动泄水阀进行了结构设计,计算并确定结构参数,利用ANSYS CFX进行模拟仿真试验.田间性能试验结果表明,该滚移式喷灌机各项指标都满足要求,喷灌机向前移动时支管产生的最大挠度为2.7 m,喷灌均匀度为92.45%,喷灌强度为12.59 mm/h.该研究为滚移式喷灌机的进一步发展提供参考.     

Newly simplified method for hydraulic design of micro irrigation laterals based on emission uniformity

An analytical approach was developed to design a single uniformly sloping lateral in the micro irrigation systems. Emission uniformity was used as the water application uniformity criterion. Ene rgy relations based on the energy gradient line approach were revamped to account for the spatial va riance of emitter outflow and the emitter connections local energy losses. Four pressure head grade line profiles were distinguished: uphill, horizontal, gentle downhill and steep downhill. Analytical expressions of emission uniformity by hydraulic variation for each pressure profile were developed based on the design variables: length and diameter of lateral, emitter spacing, emitter flow equation parameters, equivalent length characterizing local losses and ground slope. The design conditions for selecting emitter type, the number of emitters per plant and designing the diameter of the uphill and steep downhill laterals were also developed. The nonlinear equations for determining lateral diameter and lateral length were solved iteratively by using the built in root finding function of (Tools> Goal Seek…) in the calculation spreadsheet of Microsoft Excel. The procedures also provide the options to fix the design lateral diameter with the commercial standard size or fix the design lateral length based on the field size. The operating inlet pressure and maximum amplitude of the pressure head throughout the lateral could also be determined easily by the procedure. Two numerical applications with various slope combinations indicate that the proposed analytical approach produces results close to the accurate stepwise numerical solutions. In comparison with Keller method, the proposed approach could produce more appropriate designs.     

轻小型喷灌机组的运行速率与压力水头损失

为研究轻小型喷灌机组低压喷灌条件下运行速率的合理取值以及工作压力与喷灌机组压力水头损失的关系,以轻小型喷灌机组为研究对象,经过室内喷灌试验,研究了一定工作压力和流量条件下机组的运行速率、灌水定额之间的关系,并对机组的局部水头损失和沿程水头损失进行了分析.结果表明:灌水定额与轻小型喷灌机组的运行速率、工作压力有一定的关系,通过确定灌水定额,能够调制出相应的运行速率.轻小型喷灌机组卷盘车处入口压力增大,喷水车单喷头处的压力也随之增大,但是入口压力增大到一定程度后,单喷头压力的提高幅度减小,因此在机组正常工作范围内,可以通过适当降低机组的入口压力,以减少机组的压力水头损失,节省能耗,降低机组的运行成本.轻小型喷灌机组在中国有广泛的发展前景,该项研究对于中国轻小型喷灌机组的性能改良具有重要意义,为轻小型喷灌机组的发展提供参考依据.     

Effects of applied water and sprinkler irrigation uniformity on alfalfa growth and hay yield

This study was conducted to investigate the effects of applied water and sprinkler irrigation uniformity on alfalfa (Medicago sativa L.) growth and hay yield in a semi-arid region. Field experiments were carried out in 2006 in Varamin, Iran, on three plots of 25 m × 30 m. Each plot was subdivided into 25 subplots of 5 m × 6 m. Different irrigation depths and sprinkler water uniformities were obtained by various scenarios of sprinkler nozzle pressure. In each plot, applied water was measured at 250 points (125 points above and 125 points below canopy) and the soil water content of 40 cm deep below soil surface was monitored at 25 points, each in the center of a subplot, throughout the irrigation season. The results showed that sprinkler water and soil water content uniformity varied between 66-78 and 88-91%, respectively. The findings revealed that soil water content uniformity was around 20% higher than sprinkler water uniformity. The irrigation uniformity below the canopy was estimated to be 2.5% greater than above the canopy, and canopy-intercepted water could account for 11-15% of the total seasonal applied water. Evaluation showed that alfalfa leaf area index relies more heavily on farm water application uniformity than hay yield and crop height. The experimental results illustrated that water distribution in sprinkler irrigation systems has a direct effect on alfalfa growth, hay yield and water productivity such that the applied water reduction and the increased sprinkler water uniformity led to an increased alfalfa water productivity of 2.41 kg m⁻³.     

河套灌区渠系优化配水模型应用研究

优化渠系配水过程是缓解灌区水资源压力、实现农业高效节水的重要举措.以河套灌区总干渠、干渠两级渠系作为研究对象,将水流过渡平稳和渠道渗漏量最小作为优化目标,建立渠系优化配水模型,采用回溯搜索算法(BSA)、多目标粒子群算法(MOPSO)以及向量评估遗传算法(VEGA)进行求解.结果显示,BSA,MOPSO,VEGA这3种算法所求的配水时间分别为30.96,11.65,29.96 d; 3种算法所得的阀门开启时间点的偏态系数分别为-0.048,0.068,0.566,表明BSA和MOPSO更能保证灌溉水在渠道运输中的稳定性.考虑渠首水位季节性变化对灌区引水时间产生的限制作用,BSA和MOPSO分别更适用于渠首引水量较少、充足的情况.考虑配水时间的集中程度以及干渠的地理位置分布,BSA和MOPSO更有利于实施分区管理措施.     

Factors affecting the economic benefits of sprinkler uniformity and their implications for irrigation water use

Adoption of more uniform sprinkler systems involves a trade off between increased capital expenditure on equipment and the benefits associated with reduced water application when application is uniform. An empirical analysis of the economics of lettuce production, grown using sprinkler systems under the windy conditions of the Swan Coastal plain in Western Australia is presented, where the yield response to water exhibits eventual declining marginal productivity. A range of sprinkler designs that have been field-tested for performance were examined. The optimal per-crop water application for the least efficient system was up to double the application rate of the most efficient system. However, the economic analysis demonstrates that there are clear incentives for adopting more water-efficient systems despite the higher capital cost, because of the yield depressing effect of over-watering. Sensitivity analysis demonstrates substantially poorer incentives for improving irrigation efficiency when yield relationships follow a Mitscherlich functional form.