摘要
加气滴灌在作物提质增产和提高水肥利用效率方面展现出优势,为提高气体在水中的稳定性,该研究设计了旋流式微纳米气泡发生装置,从与内腔相切的进口流道引入气液混合流,利用椭球形内腔迫使液体旋流,并在两端喷孔处螺旋向外喷出,形成剪切作用破碎气泡。通过正交试验、高速摄影和纳米粒度分析技术,研究装置内腔结构(长轴、短轴、进口直径和喷孔直径)对气泡特征(数量、粒径和均匀度)和溶氧量的影响。试验结果表明:1)随着装置运行,60~250μm的大气泡粒径分布不变,10~60μm的小气泡平均粒径在运行2 min内增加20%。装置停止1 min后,100μm以上的大气泡消散,停止3 min后,水中60μm以下的微气泡数量减少约70%,留下直径小于30μm的微纳米气泡悬浮于水中。2)装置各结构中,喷孔直径和短轴对微气泡生成阶段的影响最显著,长轴对停止后水中60μm以上的大气泡平均粒径、均匀度,以及小气泡数量影响最大,进口直径虽在运行时和停止后均对微气泡数量影响最小,但依然达到显著水平(P<0.05)。纳米级与微米级气泡生成特征上表现一致。3)溶氧试验中,水中含氧量变化分为三个阶段:运行增氧阶段、溶氧衰减阶段、溶氧稳定阶段。溶氧增加与衰减过程受进口直径影响最大,而稳定后的溶氧效果受短轴和长轴影响显著。装置溶氧效果与气泡生成效果呈正相关,且同结构尺寸在气泡生成和溶氧效果上的表现一致。以气泡个数多、粒径小、均匀度和溶氧量高为目标,得到长轴80 mm、短轴45 mm、进口直径12 mm、喷孔直径3 mm为最优参数组合。研究结果可为加气滴灌中新型加气设备的设计与研制提供参考。
Aerated subsurface drip irrigation(ASDI)can improve soil aeration,crop yield,water,and fertilizer use efficiency.In this study,a micronano-bubble generator was designed to stabilize the gas in water,according to the cyclonic shear fragmentation.A gas-liquid mixing flow was also introduced from the inlet runner tangent to the inner cavity.The ellipsoidal inner cavity was used to force the liquid into the cyclone and then spiral outward at the two ends of the spouting holes.As such,a shear effect was formed to crush the bubbles.A 4-factor and 3-level orthogonal test L9(34)was designed to explore the effects of structural parameters on the generated bubbles and the performance of dissolved oxygen.The following specifications were:the major axis(40,60,and 80 mm),the minor axis(30,45,and 60 mm),the inlet diameters(8,12,and 16 mm),and the spray holes diameter(2,3,and 4 mm).High-speed photography,image processing,and nano-particle size analysis techniques were used to extract the features,such as the number,particle size,and uniformity of micro-nano-bubbles,in order to monitor the dissolved oxygen in water over time.The results show that the distribution of particle size was basically unchanged in the large bubbles from 60 to 250μm with the operation of the device,while the average size of the small bubbles from 10 to 60μm increased by 20% within 2 min of operation.Specifically,the large bubbles above 100μm were basically dissipated,after the device was stopped for 1 min.Then the count of small bubbles below 60μm in the water was reduced by about 70% after 3 min of stopping operation.The micro-nano-bubbles with diameters of less than 30μm were finally suspended in the water.In addition,the performance of the device showed that the bubble generation during the operation depended the most significantly on the spray hole diameter and minor axis.The major axis shared the greatest effect on the average particle size and the uniformity of large bubbles above 60μm in the water after operation,as well as on the number of
作者
王剑
王夺
王秀礼
王新坤
陈瑞
刘正亮
WANG Jian;WANG Duo;WANG Xiuli;WANG Xinkun;CHEN Rui;LIU Zhengliang(Research Center of Fluid Machinery Engineering and Technology,Jiangsu University,Zhenjiang 212013,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2024年第14期33-43,共11页
Transactions of the Chinese Society of Agricultural Engineering
基金
江苏省农业科技自主创新项目(CX(21)3078)
国家自然科学基金项目(51709130)。
关键词
灌溉
试验
优化
微纳米气泡
粒径
溶解氧
irrigation
experiment
optimization
micro-nano bubbles
particle size
dissolved oxygen
