黄河水滴灌系统灌水器结构-泥沙淤积-堵塞行为的相关关系研究

Cascade relationship between the emitter structure-sedimentation-clogging behavior in drip irrigation systems with Yellow River water

传统的黄河水沉淀-过滤系统存在沉沙池建设成本高、过滤器频繁反冲洗能耗高等问题,让更多的细颗粒泥沙随水流排出灌水器体外是解决黄河水滴灌系统灌水器堵塞的新思路,而摸清泥沙在黄河水滴灌系统内部的淤积特性以及灌水器结构-淤积泥沙特性-堵塞特性参数间的相关关系是探索其排沙能力的前提和基础。为此,本文在河套灌区开展了黄河水滴灌系统灌水器堵塞原位试验,系统分析了6种内镶贴片式灌水器内部细颗粒泥沙含量及粒径分布动态变化特征,探索了三者间的级联关系。结果表明:进入灌水器内部的泥沙99%以上可以排出体外,淤积在灌水器内部的泥沙以粉粒为主、砂粒次之、黏粒最少。随着灌水器堵塞加剧,内部淤积泥沙的黏粒、粉粒比例相对降低,而砂粒比例相对增加,泥沙进入灌水器后存在聚集等行为,使得灌水器内部淤积泥沙粒径明显高于毛管入口。泥沙比表面积淤积量、粉粒比例、砂粒比例、D50、D95对黄河水滴灌系统Dra、克里斯琴森均匀系数CU影响显著(p<0.05),不同灌水器淤积泥沙粒径明显不同,D50与灌水器结构无量纲参数(流道宽深比W/D、面积长度比A1/2/L)及断面平均流速v显著(p<0.05)相关。本研究对引黄滴灌灌水器设计及灌溉系统过滤配置具有指导意义。

Traditional sedimentation and filtration systems used in Yellow River water treatments has disad⁃vantages in high cost of construction for desalting basin and high energy consumption due to frequent filters self-washing.It is mainly because of the high-concentration fine-grained sediment involved,and thus im⁃proving the sediment discharge capacity of drip irrigation emitters has become a new method to solve the re⁃lated clogging issue.Figuring out the relations among the emitter structure,sedimentation and clogging char⁃acteristics is the premise and basis.Therefore,an in-situ emitter clogging experiment was carried out in Hetao Irrigation District,Inner Mongolia.The dynamic variation characteristics of fine-grained sediment con⁃tents and particle size distribution in six types of emitters were systematically analyzed,and the correla⁃tions between them were explored in this paper.The results showed that more than 99%of sediments those entered the emitter could be discharged with the flow.The sediments deposited in emitter was mainly com⁃posed of powder particles,followed by sand particles and then clay particles.As emitter clogging becoming more serious,the proportion of clay and powder particles both reduced,while that of sand increased.After the sediments entered the emitter,aggregation and other processes made the particle size that inside emit⁃ter significantly increased,comparing with those at the emitter inlet and in the water source.The silt specif⁃ic surface area amount,powder ratio,sand ratio,D50,D95 showed significant impacts on average discharge variation rate(Dra)and Christiansen coefficient of uniformity(CU).Sediment size in six types of emitters were obviously different.D50 was significantly related to the dimensionless parameters of the emitter struc⁃ture(flow channel width to depth ratio,W/D;area length ratio A1/2/L)and the average cross-sectional ve⁃locity v(p<0.05).This study might be of guiding significance for the design of drip irrigation emitters and the filtering configuration when utilizing the Yellow River water.