低水头微喷带喷洒特性试验研究

发布时间：2018-10-19 16:56

【摘要】：微喷带是多孔出流薄壁塑料软管,出水小孔按一定规律组成节点并沿管长方向等距布设,未充水时呈扁平带状,充水时水流从管带上部的小孔喷出,受到空气阻力的作用而破碎成水滴,喷洒到地面形成湿润区。在田间灌溉条件下,毛管处的水压一般较低,通过提高管带内水压力来提高喷洒均匀度较为困难,因此研究低水头下微喷带的喷洒特性对于提升微喷带的灌溉效果很有必要。为分析在低水头条件(1~5m)下工作压力、铺设长度和铺设间距三者对微喷带喷洒特性的影响,首先,以国内常见的N45(折叠带宽为45mm)单列斜5孔微喷带为研究对象,进行了单管的喷洒特性试验。研究中使用Surfer软件绘制了单管的水量分布等值线图,分析了单管沿管长方向的水量分布特征,采用克里斯琴森均匀系数评价喷洒均匀度。然后,以单管水量分布规律为基础,通过叠加模拟计算得到微喷带双管组合的喷洒效果参数,同时,结合Surfer软件绘制的水量分布等值线图分析双管组合在不同铺设长度、不同工作水头、不同布置间距下的喷洒特性。试验结果表明:(1)Surfer软件是绘制水量分布等值线图的简便工具,能够帮助研究者直观了解喷洒水在湿润区内的分布情况,为喷洒特性的定性分析提供参考。(2)微喷带单管沿管长方向的喷洒均匀度受工作水头和铺设长度影响较大。铺设长度一定时,工作水头增大则单管的喷洒均匀度增大;工作水头一定时,铺设长度减小则单管喷洒均匀度增大。(3)为保证湿润区内喷洒均匀,N45单列斜5孔微喷带在小于3m工作水头下,单管铺设长度不宜超过20m;在3~5m工作水头下,单管铺设长度不宜超过40m。双管组合在低水头下铺设长度不宜超过30m;在3~5m水头下,铺设间距应在4~6m之间。(4)为方便田间布置,微喷带布置间距不宜过小。因此,在3~5m低水头下20m~30m长度单列斜5孔微喷带双管组合通常可控制喷洒3~4畦,而长度大于40m的微喷带可作为补充灌溉措施应用在田间。(5)与喷灌相比,微喷带的喷洒均匀度并不高,应建立符合其喷洒特性的喷洒均匀度评判标准。在5m以内水头下,斜5孔微喷带单管首尾两端的喷洒均匀度不应小于60%。(6)在特低水头条件下,微喷带可小孔朝向下方靠近植株根部铺设,能够达到微量灌溉的效果。与滴灌和微喷灌相比,节水成本有效降低。本研究结果对于微喷带设计参数的优化、田间灌溉管网的合理布置具有指导意义。
[Abstract]:The micro-jet belt is a porous thin-wall plastic hose, and the outlet orifice is arranged equidistant along the length of the pipe in accordance with certain rules. When the pipe is not filled with water, the water is flattened and the water is ejected from the small hole in the upper part of the pipe belt. It is broken into droplets by air resistance and sprayed on the ground to form a wet zone. Under the condition of field irrigation, the water pressure in the capillary tube is generally lower, so it is difficult to improve the uniformity of spraying by increasing the water pressure in the pipe band. Therefore, it is necessary to study the spraying characteristics of the micro-spray belt under the low water head in order to improve the irrigation effect of the micro-spray belt. In order to analyze the effect of working pressure, laying length and laying spacing on the spray characteristics of microspray belt under the condition of low water head (1m), the domestic common N45 (folding bandwidth is 45mm) single-row oblique 5-hole microspray belt was used as the research object. The spraying characteristics of single tube were tested. In the study, Surfer software was used to draw the isoline map of the water distribution of single pipe, and the water distribution characteristics along the length of the pipe were analyzed, and the uniform coefficient of Christiansen was used to evaluate the uniformity of spraying. Then, based on the water distribution law of single pipe, the spraying effect parameters of double pipe combination of micro-spray belt are calculated by superposition simulation. At the same time, combined with the isoline map of water distribution drawn by Surfer software, the double pipe combination is analyzed in different laying lengths. Spraying characteristics under different working head and different arrangement spacing. The results show that: (1) Surfer software is a simple tool for drawing the contour map of water distribution, and it can help researchers to understand the distribution of spraying water in the wet area. It provides a reference for qualitative analysis of spraying characteristics. (2) the spray uniformity along the length of the pipe is greatly affected by the working head and laying length. When the laying length is fixed, the spray uniformity of a single pipe increases with the increase of the working head, and when the working head is fixed, (3) in order to ensure the uniformity of spraying in wetted area, the length of single pipe laying should not exceed 20m in the case of N45 single row inclined 5 hole micro-spray belt under less than 3m working head, and the length of single pipe laying should not exceed 40m under 35m working water head. The laying length of the double pipe combination should not exceed 30m under the low water head, and the laying distance should be between 4m and 6m under the 35m head. (4) for the convenience of field arrangement, the spacing of the micro-spray belt arrangement should not be too small. Therefore, under the low water head of 35 m, the 20m~30m length single row inclined 5 hole microspray belt and double pipe combination can usually control spraying 3 / 4 bed, while the longer than 40 m microspray belt can be used as a supplementary irrigation measure in the field. (5) compared with the sprinkler irrigation, the microspray belt can be used as a supplementary irrigation measure. (5) compared with the sprinkler irrigation, The spray uniformity of microspray belt is not high, so it is necessary to establish the evaluation standard of spraying uniformity in accordance with its spraying characteristics. Under the water head of less than 5 m, the spray uniformity of the two ends of the single tube should not be less than 60. (6) under the condition of very low water head, the microspray belt can be laid near the root of the plant towards the bottom, and the effect of micro-irrigation can be achieved. Compared with drip irrigation and micro sprinkler irrigation, the cost of water saving is reduced effectively. The results of this study are of guiding significance for the optimization of design parameters of micro-spray belt and the rational arrangement of irrigation pipe network in the field.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S277.94

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