【作者】 潘林；

【导师】 肖新棉；

【作者基本信息】 华中农业大学 ， 农业机械化工程， 2007， 硕士

【摘要】 随着世界性水资源的日趋紧张，采用包括喷微灌在内的节水灌溉技术已成为世界各国为缓解水资源危机和实现农业现代化的必然选择。一种新型喷灌技术——非圆形域喷洒灌溉技术，利用变量喷洒可控域精确灌溉喷头组合进行喷灌，从根本上解决现有圆形喷洒域喷头从几何学上不利于组合的问题。本文围绕非圆形域喷洒灌溉技术关键技术的实施进行了较为全面深入的研究，并引入了流动数值模拟技术，分析了流道结构与能量损失等的关系，从而为设计出高效率、低能耗的射程调节机构提供理论依据。非圆形域均匀灌溉喷头是根据被灌溉地块或区域形状变化的要求进行喷洒的一种精确灌溉喷头。本文总结了国内外非圆形域均匀灌溉喷头研究进展及实现方法，指出了国内研究和应用中存在的主要问题。通过理论分析，研究了非圆形喷洒域均匀灌溉喷头的实现。在总结国内外现有实现方法的基础上，给出了非圆形域实现机构的一般组成。并以正方形和正六边形喷洒域为例，研究了非圆形喷洒域均匀灌溉喷头工作时射程的变化规律以及射程、流量、转速应服从的关系。非圆形域喷头的工作方程表明，喷头的流量与射程平方和转速的乘积成正比。在分析与总结国内外流体流动模拟研究的基础上，探讨开展非圆形域喷头调节器内部水流运动数值模拟的意义。本文以调节器内部三维湍流流场为研究对象，采用数学分析和数值模拟方法对湍流管内流场结构进行研究。利用三维雷诺时均Navier-Stokes方程和Realizable k- e两方程湍流模型，以商用软件FLUENT作为研究平台，对进出水流道中的流态进行了数值计算与分析，获得了整个流域内的速度、压力等的分布云图。在前人研究的基础上，设计了喷头实现非圆形域灌溉的关键部件—非圆形域喷头调节器，并采用水流运动的局部阻力理论对其结构参数进行了分析，确定试验样品结构。研究建立了变量喷洒可控域精确灌溉喷头性能评价指标体系，对加装了调节器试件喷头的水力性能参数，如工作压力、流量、射程、喷洒水分布特性等进行了测试评价，实验结果表明，除了满足普通摇臂式喷头的灌水质量性能要求，非圆形域喷头也能满足非圆形域喷洒的一些特殊性能要求。更多还原

【Abstract】 With the intension of world water resources shortage, water-saving irrigation techniques including the sprinkler irrigation have been the inevitable one to reduce the crisis of water shortage and to achieve the modernization of agriculture. Irregular Wetted Area Precision Sprinkler Irrigation, which is a new sprinkler irrigation technology, uses the High Uniformity Sprinklers for Irregular Wetted Area spaced together, which can eliminate the adverse influences from the circle wetted area contour on the spacing of sprinklers. This paper conducts a systematical research on the Irregular Wetted Area Precision Sprinkler Irrigation and analyzes the relation between configuration and energy losing with CFD technology. The results of this research provide theoretical basis for the design of high uniformity sprinkler for irregular wetted area.The term "High uniformity sprinklers for irregular area" is used by the authors to describe the precision irrigation sprinklers that can spray according to the continuous change of the irrigated area profile. A survey on high uniformity sprinklers for irregular spraying area was made by analyzing the present mechanism at home and abroad in this paper. The major models and components of these sprinklers were discussed. The problems which existed in the development and practice of this field in China were put forward. The realization of high uniformity sprinklers for irregular wetted area was researched by theoretical analysis in this paper. The general construction and principle of the spray distance and flow rate adjustor for the sprinkler are given by analyzing the present mechanism at home and abroad. And with examples given, both the variation principle, which describes the spray distance, and the equation, which describes the internal connection of the spray distance, flow rate and rotation speed ware derived. The equations indicate that the flow rate is proportional to the product of rotation speed and square spray distance.Based on analysis of the current state of the flow pattern modeling abroad and at home, the meaning of the mathematical simulation of the flows in the Irregular Area Spraying Adjustor is given. This paper discusses the three dimensional turbulent flow fields, using methods of mathematical analyze and CFD simulation. The flow characteristics of the adjustor are numerically studied using Realizable k-e turbulent model combined with 3D time-averaged N-S equation through commercial CFD software package FLUENT, and the results give the distribution figures of velocity, pressure, etc. in the whole flow field are obtained.After reviewing the current researches, Irregular Area Spraying Adjustor, the key component for the high uniformity sprinklers for irregular area achieving variable rate and contoured controlled is designed. The main constructional parameters are analyzed under Water Movement Partial Resistance Theory. The index system for evaluation of sprinklers’ performance is given. The hydraulic parameters of the sprinkler installed with adjustor are tested, such as working pressure, water flux, the range of the sprinkler, characteristic of water distribution, etc. The experimental results indicate that the high uniformity sprinklers for irregular area not only ensure the consistency with the common standard, but also the special standard for Irregular Area Spraying.更多还原