导　　师： 胡笑涛

学科专业： 082802

授予学位： 硕士

作　　者： ;

机构地区： 西北农林科技大学

摘　　要： 压力补偿滴头具有出流量均匀，抗阻塞性强，自动冲洗等优点，但其流道尺寸微小，目前主要采用试验方法研究其宏观水力特性与抗堵塞性，对其内流场分布与工作性能之间的关系缺乏深入的认识。压力补偿滴头的工作原理是压力水流运动与结构变形耦合的结果，采用计算流体动力学方法研究无法准确反映压力补偿滴头内的流场分布，需要使用流固耦合动力学理论及方法研究。本文在分析了流固耦合应用情况及压力补偿滴头水力特性与抗堵塞性的研究现状的基础上提出采用流固耦合数值分析与宏观实验相结合的方法研究压力补偿滴头的性能，分析流道结构、膜片变形与滴头水力性能之间的关系，为设计和开发新型压力补偿滴头提供依据。得到的主要结论有： （1）对4种不同结构形式的滴头进行了水力特性试验研究，并对其中滴头中3种压力补偿滴头抗堵塞性进行了试验测试。通过对试验滴头压力-流量关系及滴头平均流量、堵塞率随沙粒浓度的变化曲线的分析，发现随着入口压力的增大，压力补偿滴头出流量较非压力补偿滴头稳定，流态指数较小。滴头的抗堵塞性不是绝对地随着滴头流量的增大而提高。 （2）采用流固耦合数值分析方法研究了压力补偿滴头的水力性能，利用建模软件Pro//E建立了进行数值模拟研究压力补偿滴头滴头壳体模型，使用GAMBIT建立了其流道模型，用计算流体动力学与计算结构学商业软件进行其水力特性研究。得到压力流量关系结果与室内试验实测值比较，最大偏差不超过10/%，表明用此方法研究压力补偿滴头的水力特性结果可靠；得到一定工作压力下补偿元件弹性膜片的变形量、获得压力补偿滴头内流场分布，为理解压力补偿滴头的工作原理、研究其工作性能提供了一种可视化途径，为开发新滴头，缩短研制周期，降低开发成本提供一定的参考。 （3）利用液固两相流理论与流固耦合数值模拟方法，研究了压力补偿滴头内悬浮颗粒分布规律，通过对不同入流颗粒体积分数及不同颗粒粒径时的滴头内流场的模拟，得到了滴头内水流及颗粒速度的分布和颗粒体积分数的分布。结果表明，入流颗粒粒径越大，颗粒体积分数越高，压力补偿滴头的出流量越小；滴头流道内存在缓水区，水相与固相流速接近，且同一位置水相流速较固相流速略大；滴头内每层环形流道入口处及外层流道右侧颗粒体积分数增大，容易产生固相颗粒沉淀累积。此结果为改进滴头结构及提高其抗堵塞性提供了参考。由模拟结果可以看出，要提高滴灌系统的抗堵塞性，除了要改进滴头的结构，增加其湍动能力，提高其自身的抗堵塞性外，还需要改进过滤设施，减小管道内的颗粒体积分数及颗粒粒径，从而减小滴头的入流颗粒体积分数及颗粒粒径，有效提高滴头的出流量。 该方法能够得到压力补偿滴头内悬浮颗粒分布规律，可为研究滴头的抗堵塞性提供参考。 The pressure compensating emitters have the advantages of constant flow under thechange of pressure anti-clogging and self-cleaning performance. It was mainly usingexperimental methods to study the hydraulic and anti-clogging characteristics because of itssmall channel size. It was lack of deeply understanding of the relationship betweendistribution of flow field and performance of work. The working principle of pressurecompensating emitter is the result of pressure flow coupling with structure deformation. Toreflect its distribution of flow field accurately, it need using Fluid-Structural Interactionmethods. In this paper, Fluid-Structural Interaction simulation and experiments wereconducted to study the relationship of channel structure and elastic diaphragm deformationwith hydraulic characteristics of pressure compensating emitters. Follow are the mainconclusions: /(1/)Experiments were conducted to study the hydraulic and anti-clogging characteristicsof different structural emitter. After analysising the pressure-flow relationship, average flowand clogging rate, we found that, as the inlet pressure increase, the flow rate of pressurecompensating emitter is more uniform than that of non-pressure compensating emitter. Thepressure compensating emitter has the smaller fluid index. When the flow rate increases, theemitter anti-clogging characteristic is not improve absolutely. /(2/)Pressure compensation emitter shell model was established by a modeling softwarePro//E. The channel model, which was used to simulate the flow field within emitter, wasestablished by GAMBIT and calculated Fluid-Structural Interaction by the commercialsoftware. The results were compared with traditional emitter’s hydraulic performance tests. Itshows that simulating flow mostly were bigger than fact flow, but the windage was under10/%, indicating that the method is a feasible way to study the hydraulic characteristic ofpressure compensating emitter. The volume deformation of elastic diaphragm and thedistribution of inter-liquid field under the certain pressure were obtained. Numerical visualization can be easier to understanding work principle and performance of pressurecompensating emitter. It is also realize low cost and high efficiency development of highquality emitter. /(3/)Based on fluid-structure interaction and two phase flow theory, the granuledistribution in the pressure compensating emitter was simulated. The results indicate thatnumerical simulation is a new and strong feasibility method to study and improve emitterperformance. The paper analyzed flow rate, the velocity distribution of water and granulevolume fraction under different granule diameters and initial volume fraction in a pressurecompensating emitter. We can conclude that the flow rate was reducing with the increase ofgranule diameter or initial volume fraction. Water velocity is a little larger than granule’s insame position. The granule volume fraction increases in the local channel where is easier tobe clog by sedimentary granule. To improve the anti-clogging of drip irrigation system, weneed not only to improve the structure of emitter to enhance its dynamic ability, but also toimprove filter facilities to reduce granule diameters and volume fraction in channel of pipe.

关 键 词： 压力补偿滴头 流固耦合 数值模拟 水力特性 抗堵塞性

分 类 号： [S277.95]

领　　域： [农业科学] [农业科学]