滴灌管主流道沿程压力分布模型及验证  

Modelling and verification of pressure distribution along mainstream in drip irrigation pipe

作　　者：丁法龙 茅泽育[1] 王文娥[2] 韩凯 Ding Falong;Mao Zeyu;Wang Wen’e;Han Kai(Department of Hydraulic Engineering,Tsinghua University,Beijing 100084,China;Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas,Ministry of Education,Northwest A&F University,Yangling 712100,China)

机构地区：[1]清华大学水利水电工程系,北京100084 [2]西北农林科技大学旱区农业水土工程教育部重点实验室,杨凌712100

出　　处：《农业工程学报》2019年第3期117-124,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家重点研发计划(2016YFC0402504)

摘　　要：为揭示滴灌管的沿程流动特性,简化滴灌水力计算,分析了能量方程应用于滴灌管水力计算的局限性,并以质量守恒和动量守恒定理为依据,建立了以滴灌管为典型的变质量流动数学模型,并结合测压试验数据,获得了滴灌管主流道沿程压力分布表达式。变质量流动的动量方程表明:多孔管路主流道压力变化取决于摩阻项和动量交换项两部分,沿程压力分布的具体形式取决于二者作用的相对强弱,滴灌管压力分布归结为求解滴灌管轴向流速分布、摩阻系数和动量交换系数,动量方程建立的合理之处在于不必追究其详细机制,将复杂的流动机理进行了合理概化。测压-测流试验表明:滴灌管轴向流速分布指数与滴头自身特性参数无关,而与滴头安装个数呈线性关系。基于理论分析和试验数据回归得到了动量交换系数的表达式,并结合Blasius摩阻公式进行方程求解,压力计算值与实测值吻合良好,最大相对误差为4.27%。该文可为滴灌管水力计算及多孔管水动力学研究提供一定参考。Irrigation uniformity is the core evaluation index of drip irrigation.The influence factors of irrigation uniformity include pressure along mainstream way,emitter manufacturing deviation and emitter clogging,etc.,but the leading factor is the longitudinal pressure distribution.Therefore,calculation of pressure is prerequisite for hydraulic design of drip irrigation system,and it is also the most basic problem for the study of drip irrigation hydraulics.Scholars at home and abroad have done a lot of research on this problem.According to the author's references,all the past research results were based on the energy conservation law,researchers mainly calculated the frictional head loss to determine the pressure distribution along drip irrigation pipe,and the friction resistance was the default for the only factor affecting the pressure distribution.However,this method neglects the energy of the fluid flowing through sidewards orifices,and it is not completely applicable to the drip irrigation pipe.To reveal the behavior of variable mass flow,and simplify the hydraulic calculation of drip irrigation pipe,this study established the basic equation of variable mass flow based on mass conservation and momentum conservation theories,and thus developed an analytical model of pressure distribution along mainstream in drip irrigation pipe.Momentum equation of variable mass flow is clearer in physical meaning,and it does not require to investigate the complex flow mechanism in detail,but rather rationally simplify uncertain factors.The developed model shows longitudinal pressure profile in drip irrigation pipe is determined by the friction loss and the momentum exchange,the friction loss tends to decrease the pressure while the momentum exchange just the opposite.The solution of pressure in mainstream way is attributed to determination of friction coefficient and momentum exchange factor.The friction coefficient of drip irrigation pipes could be determined by Blasius resistance formula,according to many existing research con

关 键 词：灌溉 模型 压力 主流道 变质量流动 摩阻作用 动量交换 

分 类 号：S275.6[农业科学—农业水土工程]