滴头插入式毛管局部水头损失模拟研究  

Numerical study on minor head loss of on-line emitters in drip irrigation laterals

作　　者：王亚林[1] 朱德兰[1] 陈俊英[1] 郑超[1] 刘燕芳[1] 宋博[1] 

机构地区：[1]西北农林科技大学中国旱区节水农业研究院,陕西杨凌712100

出　　处：《水力发电学报》2016年第4期22-31,共10页Journal of Hydroelectric Engineering

基　　金："十二五"国家科技支撑计划(2011BAD29B02);教育部;国家外国专家局"111"计划项目(B12007)

摘　　要：滴灌是目前最有效的节水灌溉方式之一,而准确计算毛管水头损失是滴灌设计的前提。毛管沿程水头损失的计算已基本形成统一认识,而局部水头损失规律因滴头形状的复杂性和布置方式的多样性仍没形成一致认识。为探明滴头插入对毛管水流局部阻力及流动特性的影响,本文对两种插入式毛管进行灌水试验,同时采用计算流体力学(CFD)数值模拟并分析验证,结果表明数值模拟与试验吻合度较高,可用数值模拟研究插入式毛管局部水头损失。在此基础上对9组滴灌管进行模拟研究,分析了不同流态下毛管局部水头损失系数影响因素。结果表明层流和紊流流态下,毛管局部水头损失系数均随雷诺数的增大而减小,随滴头毛管断面面积比的增大而增大;毛管局部水头损失占沿程水头损失之比值与滴头间距和滴头流量有关;毛管层流段水头损失相对较小,在不需精确计算时可忽略不计。研究结果可为管网水力计算提供参考。Drip irrigation is one of the most effective irrigation methods in water saving irrigation, and accurate calculation of the head loss in its trickle laterals is the basis for its design. Calculation of the frictional head loss has been basically formed into a unified understanding, but the trends of minor head loss have not yet come to an agreement due to the complexity of emitter forms and diversity of emitter layouts. To examine the effects of on-line emitters on the local flow resistance and flow characteristic of laterals, this study has conducted laboratory tests on two types of laterals with different emitters. Water flows in these laterals were simulated using a computational fluid dynamics（CFD） method, and verified with the experimental data. The results show that numerical simulations were in good agreement with the experimental data and they provide useful information for investigation of the minor loss of emitters. We have conducted simulations for nine different designs of laterals and examined the influence factors of minor loss coefficient under different flow regimes. Simulations reveal that in both the laminar and turbulent flow cases, the minor loss coefficient of laterals decreased with an increasing Reynolds number, and increased with an increasing cross-sectional area ratio of the emitter to the pipe. The ratio of minor loss to frictional loss was related to the spacing of emitters and emitter discharge. The head loss of laterals in laminar regime was relatively small and may be neglected in preliminary calculation. This study would help the hydraulic calculation of drip irrigation laterals.

关 键 词：滴灌 插入式滴头 局部水头损失 毛管 数值模拟 

分 类 号：S275.6[农业科学—农业水土工程] TV131.22[农业科学—农业工程]