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。     

圆形喷灌机泵注式施肥装置设计与田间试验

圆形喷灌机水肥一体化作业时对喷洒肥液均匀性有较高要求,需要采用比例施肥装置,确保注入喷灌机的肥液流量保持恒定。为此设计了基于柱塞式注肥泵的泵注式施肥装置,并以注射喷嘴的孔口直径、安装位置以及注肥泵的电源频率为变量,进行了圆形喷灌机应用泵注式施肥装置的喷灌施肥均匀性试验。结果表明,圆形喷灌机停止状态下,注肥泵电源频率50 Hz运行时,3种注射喷嘴孔口直径和3种安装位置的组合工况下喷灌施肥的均匀系数CU为99.00%~99.65%,变异系数CV为0.46%~1.37%,其中当注射喷嘴孔口直径为2.5 mm、安装在进水管水平段位置的工况时获得的喷灌施肥均匀性最佳。圆形喷灌机行走状态下,测得单列雨量筒喷灌施肥均匀系数C*UH为88.77%~90.66%,表明圆形喷灌机采用泵注式施肥装置能够获得较高的喷灌施肥均匀性。此外,通过对比注肥泵电源频率在50 Hz和46 Hz时的喷灌施肥均匀性,发现喷头喷洒肥液的电导率总平均值与电源频率之间具有显著的正相关性,表明改变注肥泵的电源频率是圆形喷灌机实现高均匀度变量喷灌施肥的一种有效途径。     

干旱风沙区喷灌蒸发漂移损失试验研究

通过在甘肃省现场喷灌蒸发漂移损失测试结果分析，可以得出：在平均风速为0－3．4m/s的范围内，蒸发漂移损失为5．6％－15．6％；影响蒸发漂移损失大小最重要的因子是风速，其次是温度，相对湿度的影响程度最小；选择平均风速4．7m/s 以下的时间进行喷灌，可以使喷洒水利用系数可以达到0．8以上，能够满足作物的需水要求。     

圆形喷灌机注肥泵的设计与试验研究

圆形喷灌机的喷灌施肥一体化作业是国内外精准农业的研究热点,选用工作压力高、流量小且稳定的施肥装置是确保高均匀性喷灌施肥的技术关键.针对圆形喷灌机实际应用和作物施肥特点,设计了一台双缸柱塞式注肥泵,包括液力端、传动端、柱塞、密封及配套动力等,单缸设计流量为150 L/h,最大工作压力为1.0 MPa;对试制样机进行了历时100 h的耐久性试验、20%~100%行程范围的调节试验和30~50 Hz频率范围的变频调节试验.结果表明：研发的柱塞式注肥泵流量随着出口压力的增大而有所减少,但不同出口压力下,流量在100 h内的变异系数均小于5%;改变柱塞行程,泵的实际流量和理论流量几乎一致,两者间的最大差值在行程百分比为60%处,为理论流量值的7.5%;泵的流量随着电源频率的增大呈线性上升关系.试验还表明,改变柱塞行程和电源频率可以调节注肥泵的注肥流量,扩大注肥泵的流量范围.开发的注肥泵适用于圆形喷灌机等灌溉施肥系统,可实现施肥的精准控制.     

论述圆形与平移式喷灌机新旧标准主要差异

即将出版的《圆形（中心支轴式）和平移式喷灌机》标准将替代JB／T6280．1-1992《电动大型喷灌机技术条件》和JB／T6280．2-1992《电动大型喷灌机试验方法》。本标准由行业资深专家和一线工程技术人员,在对国内外行业发展趋势把握基础上,通过对我国现有从事大型喷灌机科研、生产、应用技术的总结编写而成,是相关企业...     

DYP―235型电动圆形喷灌机的研制

西北地区土地资源丰富,有大量的荒漠急需开发,这里光照充足,太阳辐射总量大,昼夜温差大,有利于农作物生长发育,是发展优质棉、油、糖、瓜果的理想基地,也是特种药材、农业、畜牧业发展的理想基地。随着我国中西部经济开发步伐的加快和农业技术的发展,人们越来越明显地意识到灌溉方式对农业生产的重要性。因此,在这一地区推广喷灌技术,有广阔的前景,是缓解用水矛盾,提高西北地区社会、经济、生态效益的重大举措。     

圆形喷灌机喷头选型及配置

圆形喷灌机作为典型的节水灌溉装备,具有自动化程度高、喷洒效果好、工作效率高等优点,近年来在我国得到很好的推广应用。圆形喷灌机的灌溉质量主要取决于使用的喷头类型及配置方式。分析了圆形喷灌机喷头从中压向低压方向发展演化过程,对各种类型喷头主要性能与参数特征进行了梳理与归纳。综述了各类喷头的结构特征与性能、配置方式等方面研究与应用现状。对圆形喷灌机喷头和配置方式的研究现状分析表明,目前圆形喷灌机使用的喷头普遍为低压旋转折射式喷头,且国内外对于该类喷头的设计与性能等方面的研究尚不完善,亟待展开相关领域研究,促进该类型喷头的国产化,以满足日益增长的规模化农业对大型喷灌机的巨大市场需求。      

圆形PWM变量喷灌机喷灌特性的仿真研究

变量喷灌(Variable Rate Irrigation,VRI)是精准农业的一个重要分支,目前的发展方向是单喷头变量喷灌(Individual Sprinklers VRI,IS-VRI),即每个喷头均采用脉宽调制(Pulse Width Modulation, PWM)变量技术控制水量。为此,通过分析面向IS-VRI应用的圆形PWM变量喷灌机在喷灌过程中水量累积的过程后,数值仿真研究了PWM脉冲占空比、PWM脉冲周期、喷灌机行进角速度及喷头离围转中心距离4个参数对喷灌均匀性及喷灌水深误差的影响规律。采用Nelson R3000喷头的圆形PWM变量喷灌机数值仿真结果表明:喷灌水深与喷灌机行进角速度和喷头离围转中心距离成反比,与PWM脉冲占空比成正比,与PWM周期存在较弱的负相关关系; PWM周期和喷灌机行进角速度越小,喷灌均匀性越好,当PWM周期取10s或行进角速度取1(°)/min时,径向和周向克里斯琴森均匀系数均可达到75%和80%以上;喷灌水深误差主要出现在喷灌机中间段的径向水深误差上,约为8%,其余误差均在5%以下,水深误差可以通过调整PWM脉冲占空比补偿消除。     

法国卷盘式喷灌机在大田灌溉中的试验及应用

针对夏津县地表水资源匮乏的状况,介绍了引进的法国卷盘式喷灌机在该县的试验情况,进行了效益分析,阐述了该机的特点及出现问题的相应对策。     

圆形喷灌机典型规划设计——以内蒙古阿鲁科尔沁旗绍根镇爱民温都200 hm2人工草场为例

以内蒙古阿鲁科尔沁旗绍根镇爱民温都200 hm2人工草场利用圆形喷灌机喷灌苜蓿典型规划设计工程为例,介绍了圆形喷灌机的灌溉设计流程,包括资料收集、项目规划和项目设计。对于提高喷灌工程设计水平,改善喷灌工程质量有重要的指导意义。      

Controlling runoff under low pressure center pivot irrigation systems

A research study was conducted in commercial potato production fields irrigated by low pressure center pivot irrigation systems for three growing seasons in southern Idaho, USA. Plots were established to give several replications of both conventional and reservoir tillage under the outermost spans, where the highest application rates occur. The soil was silt loam, and the topography varied from nearly level to 5% slopes. The sprinkler devices included spray nozzles on drops (spraydrops), spray nozzles on booms (spraybooms) and rotator spray nozzles on drops (rotator spraydrops) with an operating pressure of 138 kPa.The purpose of this study was to investigate and assess the role of reservoir tillage on controlling runoff, uniformity of soil water content throughout the field, and crop yield, as compared with conventional tillage. Reservoir tillage effectively reduced runoff losses to less than 1% of the applied water, when the dike were intact and remained stable. Over the three years of this study reservoir tillage increased the average soil water content by 18%. In addition, a statistical analysis showed that reservoir tillage significantly increased the percent available water in the top 65 cm of the root zone (P=0.01). The use of reservoir tillage elevated average yield by 21%, and average percent number one tubers was increased from 64% for conventional plots to 68% for reservoirtilled plots. While reservoir tillage increased the yield significantly (P=0.01), the sprinkler type did not have a significant influence on yield.     

Characterizing pivot sprinklers using an experimental irrigation machine

In this work, a Fixed Spray Plate Sprinkler (FSPS) and two Rotating Spray Plate Sprinklers (RSPS) were compared in terms of wetted diameter, wind drift and evaporation losses (WDEL), static water precipitation pattern and dynamic water application profile. An experimental irrigation machine reproducing a pivot section was constructed and used to perform experiments in static and dynamic (linear displacement) modes. Water application from FSPS often resulted in a bi-modal pattern, while RSPS produced bell-shaped or triangular patterns. At a nozzle elevation of 2.4 m and an operating pressure of 140 kPa the wetted diameter was 1.6 m larger for the RSPS than for the FSPS. The differences between the two RSPS amounted to 0.5 m on the average. Reducing the nozzle elevation from 2.4 to 1.0 m resulted in a 2.6 m decrease in the wetted diameter. The use of RSPS may result in reduced surface runoff losses, due to the increased wetted diameter and the reduced peak precipitation rate. WDEL for RSPS were statistically related to wind speed, although no significant differences were found between both types of RSPS or between the two nozzle elevations. According to the experimental results, reducing the nozzle elevation will not result in reduced WDEL, but will increase the chances for runoff.     

Diagnosis of regional evaporation by remote sensing to support irrigation performance assessment

The success of water management in large irrigation schemes with composites of soil, crop, wetness and micro-meteorological conditions is difficult to quantify. Performance assessment indicators, being among others a function of evaporation, are useful tools to evaluate the actual functioning of an irrigation system. The inevitable spatial variability of evaporation in large irrigation schemes makes its determination with conventional point measurements almost impossible. A new remote sensing evaporation parameterization algorithm has been tested with high resolution Landsat Thematic Mapper data for the Eastern Nile Delta, Egypt. Although the implementation of such an algorithm requires assumptions to be made, the current case study shows that these assumptions do not hamper the estimation of actual and potential evaporation at regional scale. The actual evaporation has been used to express the uniformity of crop water use which is related to the equity of irrigation water distribution. The coefficient of variance in actual evaporation between 53 differenent irrigation districts is 10% on average. The relative evaporation was considered to determine whether the crop was adequately irrigated. The relative evaporation was more than 75% for 48 out of 53 irrigation districts. It is concluded, that improved information on actual crop growth conditions through remote sensing provides an essential insight into the planning of real-time and seasonal irrigation water deliveries.     

The feasibility of using variable rate water application under a central pivot irrigation system

The purpose of this paper was to assess the feasibility and significance of applying spatially variable irrigation under a central pivot system at the Federal German Agricultural Research Center, Braunschweig, Germany. The assessment was based on soil moisture holding capacity, soil depth variation and root development. Soil texture analysis was carried out by sampling on a 60 meter grid. The German Agro-Meteorological Model was applied to simulate the water balance in the crop-soil-atmosphere system for the growing season 2003/4. The research findings are presented in terms of six scenarios: 20, 30, 40 mm water application depths per irrigation under both variable rate application and uniform application. The comparison revealed that the loss of water was higher for the uniform application scenarios than that for the variable rate application (VRA) scenarios for the applications of 20 and 30 mm. The VRA scenario of 20 mm water application was found out to be the best option for water conservation.     

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.     

Canopy temperature based system effectively schedules and controls center pivot irrigation of cotton

Cotton is a perennial plant with an indeterminate growth pattern that is typically produced like an annual, but requires proper management to effectively produce high yields and good fiber quality in a thermally limited environment like the northern Texas High Plains. In 2007 and 2008, we investigated the effect of irrigation scheduling/control method and amount on cotton (Gossypium hirsutum L.) yield and water use efficiency. Methods were automatic irrigation scheduling and control of a center pivot system, and manually scheduled irrigation to replenish soil-water to field capacity. Cotton was irrigated with LEPA (low energy, precision application) drag socks in furrow dikes; three blocks were irrigated manually and three were irrigated automatically. Six replicates of the manual and automatic irrigation treatments were included in the randomized block design. Manual irrigations were based on the weekly replenishment of soil-water to field capacity in the top 1.5 m of the soil profile and included a fully irrigated treatment (I₁₀₀), and treatments receiving 67% (I₆₇) and 33% (I₃₃) of the I₁₀₀ amount, plus a non-irrigated treatment (I₀). Automatic irrigations were triggered using a time temperature threshold (TTT) algorithm, which was designated as the I₁₀₀ treatment, and treatments receiving 67%, 33%, and 0% of that amount (I₆₇, I₃₃ and I₀, respectively). In 2007, overall mean lint yields (102.3 and 101.6 g m⁻², manual and automatic, respectively) were not significantly different. Similarly, yields were not significantly different across automatic and manual treatments in the same treatment level, with the exception of the I₆₇ treatment where the manual treatment yields were 11% greater. In 2008, the mean yields were 70% less than those in 2007 for both methods of irrigation (30.3 and 30.9 g m⁻², manual and automatic, respectively) due to harsh climatic conditions at emergence and heavy rainfall and cooler temperatures in the month of August. Yields from the automatically irrigated plots in the I₁₀₀ and I₆₇ treatments, however, were significantly greater than yields from the corresponding manually irrigated plots; though there was no significant difference between yields in the drier treatments (I₃₃ and I₀) plots. These results indicate that the TTT algorithm is a promising method for auto-irrigation scheduling of short season cotton in an arid region. However, further studies are essential to demonstrate consistent positive outcomes.     

Characterisation of evaporation and drift losses with centre pivots

The objective of this paper is to study evaporation and drift losses (EDLs) with two types of sprinklers: rotating spray plate sprinklers (RSPS) and fixed spray plate sprinklers (FSPS), both installed at two different heights (1 and 2.5 m above the ground). A field test was carried out during three seasons at an irrigated plot with a centre pivot, in Albacete (Spain). The results show that EDLs were significantly higher with the FSPS placed 2.5 m above the ground (FSPS 2.5) than with the RSPS placed 1 m above the ground (RSPS 1). The EDLs obtained for the FSPS 2.5 combination were 8% for night irrigation events and 13.7% for daytime irrigation events. The lowest EDL values were registered with RSPS 1, ranging from 3.3 to 8.2% under night and day operation conditions, respectively. These results were obtained for an average wind speed of 1.3 m/s at night and 3.5 m/s during the day, and were normally below 5 m/s.     

施肥浓度对摇臂式喷头喷灌施肥均匀性的影响

为了研究施肥浓度对喷灌施肥均匀性的影响规律,选用摇臂式喷头10PY₂H,测量其喷灌施肥时肥液体积、施肥浓度、施肥量3种参数的径向分布.试验中,氯化钾溶液质量浓度(即母液浓度)分别为0,20,35,50,65,80 g/L.采用叠加法计算组合喷洒时3种施肥参数的均匀度CU、分布均匀度DU和统计均匀度U_s.分析表明施肥浓度对摇臂式喷头的灌水施肥影响呈现非线性特点.增加母液浓度对肥液体积分布和施肥浓度分布均匀性的影响相对较小,但对施肥量分布均匀性的影响十分显著.组合喷灌加剧了不同测点的数值差异.随着母液浓度增大,施肥量径向分布变化增大,当母液质量浓度增大到80 g/L时,施肥量主要集中在20%~60%射程处,导致施肥均匀性急剧下降;当母液质量浓度小于等于35 g/L时,远端90%~100%射程处的施肥浓度相对更高,与前人得出的滴灌施肥系统施肥浓度沿管道方向递减的规律相反.3个评价指标中,均匀度CU数值最高,分布均匀度DU总体数值最低、变化最大,且以DU变化最为明显,这说明了DU能反映低值区的施肥情况.喷灌施肥等值线图表明肥液与施肥量的分布规律相似,但施肥浓度的分布情况则相反,这可能与射程远端施肥浓度更大有关.