基于Ergun方程的微灌砂颗粒形状系数测定方法研究  

A Study on The Method of Determination of The Shape Coefficient of Sand Particle in Micro-irrigation Based on Ergun Equation

作　　者：李景海 翟国亮[2] 刘清霞[1] 李国强 LI Jing-hai;ZHAI Guo-liang;LIU Qing-xia;LI Guo-qiang(School of Civil and Architectural Engineering, Anyang Institute of Technology, Anyang, 455000, Henan, China;Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453003, Henan, China;Anyang No.1 Senior High School, Anyang 455000, Henan, China)

机构地区：[1]安阳工学院土木与建筑工程学院,河南安阳455000 [2]中国农业科学院农田灌溉研究所,河南新乡453002 [3]安阳市第一中学,河南安阳455000

出　　处：《节水灌溉》2020年第12期1-5,共5页Water Saving Irrigation

基　　金：安阳工学院博士科研启动基金(BSJ20190015);安阳科技计划(2020-199);中国农业科学院统筹项目(Y2019XC03-05);中国农业科学院协同创新项目(CX-0002-02-2020)。

摘　　要：形状系数表征石英砂颗粒与理想球体的差异程度,是影响砂滤层过滤水头损失和孔隙率的重要参数。为了对砂颗粒的形状特征进行准确描述,本文采用体积和砂颗粒相同的圆球外表面积与砂颗粒外表面积之比作为砂颗粒的形状系数,以粒径范围分别为1.18~1.4 mm和1.4~1.7 mm,厚度为400 mm的2种石英砂滤层为研究对象。首先,通过开展清水过滤试验,测量了滤层过滤速度及相应压降,采用注水法测量了滤层孔隙率,根据砂颗粒平均质量,计算了砂颗粒等体积当量直径。然后,根据多孔介质中液相动量方程,结合砂滤层过滤特征,对Ergun方程进行了推导,从理论上说明了Ergun方程对砂滤层的适用性。最后,根据Ergun方程,得出了砂颗粒等比外表面积当量直径,为了消除湍流对测量结果的影响,采用湍流强度对计算结果进行修正,最终得到2种滤层砂颗粒形状系数分别为0.821和0.798,最大相对误差仅为2.44,说明计算方法可行。计算结果表明,由于砂颗粒表面流动滞缓边界层的存在,随过滤速度的增加,等比外表面积当量直径计算结果呈减小趋势。同时,随过滤速度的增加,湍流稳定性逐渐增强,湍流强度则随之减小。为保证形状系数计算结果的准确性,清水过滤试验时,过滤速度的选取,应以湍流强度不低于10为控制范围。研究结论为砂滤料的选型和加工提供了技术参考。Shape coefficient is an important parameter which can influence the loss of water head and porosity of filter layer.In order to accurately describe the shape characteristics of sand particles,in this paper,the ratio of the surface area of the sphere with the same volume as the sand particle and the particle was used as the shape coefficient of sand particle,and the research objects were two kinds of quartz sand filter layer with the same thickness of 400 mm,but the diameter range were 1.18~1.4 mm and 1.4~1.7 mm respectively.Water filtration experiments were carried out in Farmland Irrigation Research Institute,Chinese Academy of Agricultural Sciences.The filtration velocity and corresponding resistance pressure drop of the filter layer were measured by experiments.At the same time,the porosity of filter layers was measured by the method of pouring water into the filter layers.And according to the average mass of sand particles,the average volume of the sand particles was calculated.Thus the equivalent diameter of equal volume sphere of the sand particles was obtained.Then,according to the momentum equation of the liquid phase in the porous medium,combining with the filter characteristics of the sand filter layers,the Ergun equation was derived.So the applicability of Ergun equation to sand filter layer was explained theoretically.Finally,according to the Ergun equation,in the condition that the filtration velocity and corresponding resistance pressure drop were given,the equivalent specific surface diameter of the sand particles was calculated.In order to eliminate the influence of turbulence on the measurement result,turbulence intensity was used to correct the calculation result of the equivalent specific surface diameter.Subsequently,the shape coefficient of the sand particles of the two kinds of quartz sand filter layer was obtained as 0.821 and 0.798 respectively.The maximum relative error of the calculation results was only 2.44%.It was proved that the calculation results of the shape coefficient were relia

关 键 词：微灌 砂过滤器 石英砂滤层 阻力压降 形状系数 过滤速度 多孔介质 Ergun方程 

分 类 号：S27[农业科学—农业水土工程] TV14[农业科学—农业工程]