【作者】 刘英超；

【导师】 侯书林；

【作者基本信息】 中国农业大学 ， 机械制造及其自动化， 2014， 博士

【摘要】 交替灌溉配套的设备存在配水均匀性差、结构复杂等问题。本文通过室内、田间试验,设计交替灌溉田间应用系统、实现交替灌溉的分配阀、为保证灌水均匀性的可调开度灌溉阀。为便于研究,将交替灌溉配水问题转化为多孔管出流问题。(1)交替灌溉多孔出流管输水能力的比较分析,设计不同孔口开度、水源水头、铺设坡度、管道长度,试验比较输水能力：得出输水管的自由出流条件下管道出流量Qz总是大于多孔出流管总出流量Q0。铺设长度L、压力水头H、管道铺设坡度i及孔间距S等任何一个因素的变化都将会对单孔出流量产生重要影响,进而影响多孔管的总出流量Q0。随着管道铺设长度L的增大总出流量增大,单孔平均出流量减小；随着压力水头H的增大,总出流量和平均单孔出流量均增大；随着铺设坡度i的增大总出流量和平均单孔出流量均增大；随着孔间距S的增大,总出流量减少,平均单孔出流量增加。分析多孔管流量折减系数ψ与无量纲数开孔比η长径比E、坡度i之间的关系,进行公式拟合。(2)建立了变孔径、变管径多孔管的数学模型,分别设计了变孔径和变管径多孔管。运用FLUENT软件研究不同入口速度,不同末孔直径对配水均匀度的影响。结果证明,变孔径、变管径多孔管相对于等孔径、等管径多孔管,可以提高配水均匀度。对于变孔径多孔管,入口速度越大,配水均匀度越高；对于DN25的PVC管道,末孔直径为10mm时配水均匀度最高；对于变管径多孔管,入口速度越小,配水均匀度越高。(3)研究设计了可调开度灌溉阀和交替灌溉分配阀。通过计算推导可调开度灌溉阀旋转转数与过水截面积的关系,并用以指导灌溉,应用FLUENT软件模拟了可调式出水口在不同开度,不同水头下的流量特性。应用可调式出水口和交替灌溉分配阀,搭建了单管和双管两种隔沟交替灌溉系统,用于田间试验,结果证明能够保证灌溉均匀度。(4)搭建兼做温室爬蔓绳的有芯微管微灌系统,并进行规划设计。以种植黄瓜为例,根据黄瓜不同生长期灌水定额,发芽期0.13L/株、幼苗期0.227L/株、初花期1.53L/株、结果期2.56L/株。对系统各级管道进行水力特征分析,经试验和计算比对选择系统主管为φ32塑料硬管、支管选择φ16塑料硬管,有芯微管芯材选择渗透系数K=0.249的丙纶丝绳。通过温室试验区与常规沟灌和滴灌比对,得出该系统灌水均匀度达93.3%,有芯微管灌水有效率96.6%,比常规有效灌水率80.5%提高近20%。单位面积投资为280元/亩,具有良好的经济效益。更多还原

【Abstract】 Currently alternative irrigation equipments have poor water distribution uniformity, complex structure and other issues. Through the laboratory, field experiment, designing alternate irrigation system and distribution valve, adjustable opening irrigation valve in order to ensure the irrigation uniformity. For the convenience of studying, transforming the alternative irrigation water allocation problem into the porous pipe flowing model.(1)Through the comparison and analysis on water capacity of the interval furrow alternative irrigation porous pipe, designing different orifice opening, water head, laying slope, pipe length, the result of the test:The free total flow Qz is always greater than the flow of porousQ0.Changes of laying slope I and hole spacing of S length L, pipeline pressure head H, any one factor will be on a single orifice flow have an important impact, thereby affecting Qo the total discharge of perforated pipe. Along with the pipeline laying length L increases the total flow increases, single hole average flow rate decreases; with increasing pressure head H, the total flow rate and the average single hole flow increased; with the laying slope I increases the total flow and the average single hole flow increased; with the hole spacing S increases, the total the flow is reduced, the average single hole flow increase. Flow reduction coefficient and the number of opening ratio, dimensionless length E, slope ratio between I size analysis of porous pipe, fitting formula.(2) Establishing a mathematical model of variable aperture, variable diameter perforated pipe, and designed them. Using the FLUENT software to study the impact of different inlet velocity, different pore diameter at the end on water distribution uniformity. Results show that variable aperture, variable diameter perforated pipe can improve water distribution uniformity. For the variable aperture perforated pipe, the higher the inlet velocity, the greater the water distribution uniformity; For the PVC pipes of DN25, when the diameter of end hole is10mm, the water distribution uniformity is highest. For the variable diameter perforated pipe, the lower the inlet velocity, the greater the water distribution uniformity; The smaller the aperture at the end, the greater the water distribution uniformity.(3) Having researched and designed the adjustable opening irrigation valve and alternate irrigation distribution valve. The calculation of adjustable open relation degree of irrigation valve rotation number and water area, and used to guide irrigation, application of FLUENT software to simulate the adjustable outlet at different opening, flow characteristics under different water head. Application of adjustable outlet and alternate irrigation distribution valve, builds single and double pipe two alternate furrow irrigation system, used for field test, results show that can guarantee the uniformity of irrigation water.(4) Build the core of micro irrigation system with microtubule and greenhouse vine climbing rope, and planning and design. To the cultivation of cucumber as an example, according to the different cucumber growth period irrigation quota, germination stage, seedling stage0.13L/strain0.227L/strain,1.53L/strain, the early flowering period2.56L/strain. Hydraulic characteristic analysis for all levels of the pipeline system, the test and calculation system supervisor of (p32plastic pipe, pipe selection of φ16hard plastic tube, core microtubule core material selection of polypropylene rope permeability coefficient K=0.249. Through greenhouse experiment area and conventional furrow irrigation and drip irrigation on irrigation uniformity, it is concluded that the system is up to93.3%, the core of microtubule irrigation efficiency than the conventional96.6%, the effective irrigation rate of80.5%increased by20%. Unit area investment is280yuan/mu, with good economic benefit.更多还原