【作者】 刘洁；

【导师】 史玉升；

【作者基本信息】 华中科技大学 ， 材料加工工程， 2010， 博士

【摘要】 灌水器产品性能的好坏直接影响微灌系统的灌水质量和使用寿命,其堵塞与开发、运行成本高的问题使得微灌技术的推广应用受到一定限制。如何实现灌水器试验样件的快速制造是开发具有自主知识产权新型灌水器的关键问题之一。本文在国家863重大专项等项目资助下,构建了灌水器结构快速定型的快速制造成套技术,揭示了灌水器迷宫流道的局部阻力特征与流道结构、工作水压、流场特征之间的变化规律,分析了不同流道断面尺寸及流道结构对灌水器堵塞的影响规律,研究了在微压条件下灌水器的流态特征、出水均匀度及其抗堵塞性能,并提出了一种变过流截面压力补偿结构的新型流道,为新型灌水器开发与性能评价奠定了理论和技术基础。在灌水器产品快速制造方面：构建了灌水器“一体式”、“分体式”快速制造方法以及小批量快速制造方法的成套技术,可用于不同类型灌水器产品结构的快速定型；系统分析了快速成形得到的灌水器产品样件表面台阶效应引起的粗糙度变化规律对灌水器结构定型精度的影响规律。在灌水器内流道局部阻力特征方面：针对五种产品的流道结构形式（齿形流道、矩形流道、菱形绕流流道、矩形绕流流道和涡流流道）分别设计1-5个流道单元的试验件,并进行了快速制造；实施了试验件在9组工作水压下的压力-流量试验,分析了流道结构、工作水压、流场特征对局部阻力特征的影响规律；比较了各流道结构局部阻力系数的试验计算值与经验值,发现对于具有复杂形状的流道,应视为一个流道整体来计算局部水头损失。在灌水器结构对堵塞性能的影响规律方面：设计并制造了6种流道结构形式13种流道断面尺寸的组合流道板,实施了从16mH20-2mH20的8组工作水压条件下的清水及强化堵塞试验；试验结果表明,0.4mm的断面深度尺寸仍可以保证6种流道形式都不容易发生堵塞；流道的宽度与深度之比大于2：1时灌水器可以获得较好的抗堵塞性能。在灌水器微压特性方面：试验发现,补偿式滴头在微压阶段补偿效果较常压时差；部分补偿式滴头由于启动临界水压的存在,导致出水均匀度也较差,但超过启动水压后则与常压时基本一致；非补偿式滴头、滴箭和滴灌带产品在微压时的出水均匀度与常压时相比没有明显变化；在强化堵塞试验中微压与常压时灌水器堵塞率有很大变化,Plastro黑色滴头、Netafim灰色滴头与大禹节水三角滴灌带这三种产品在微压条件下的抗堵塞性能良好。在新型压力补偿式灌水器的快速制造方面：提出了一种新型流道结构形式,能够直接实现流道内的过流截面随工作压力的变化而变化的压力补偿功能；设计了四组不同弹性挡片设置的流道,快速制造出流道放大模型的试验样件,并进行了压力-流量试验；试验发现等距、间隔分布弹性挡片,且挡片长度尺寸较大时,出水流量最小,并在4mH₂O～12mH₂O压力范围内具有较好的压力补偿效果。综上所述,本文对灌水器结构快速定型与快速制造、灌水器流道局部阻力特征、流道断面尺寸和结构对堵塞性能的影响以及灌水器微压特性等方面进行了系统深入的研究,同时提出了一种新型压力补偿式流道结构,研究成果将为具有自主知识产权新型灌水器的开发以及制造工艺的选择提供重要的理论和技术指导。更多还原

【Abstract】 The irrigation quality and service life of micro-irrigation system have been directly affected by properties of Drip emitter products. The promotion and applications of micro-irrigation technology have been limited due to its clogging and high running costs. In order to develop a new emitter with independent intellectual property rights, one of the key issues is how to produce drip emitters’ test sample by the method of rapid manufacturing. Under the support of some projects such as the State 863 Major Project of China, all the work in the paper had been finished. It includes to constructs rapid manufacturing sets of technology in the structure quickly stereotyped of the drip emitter and proposes a new pressure compensation channel structure with variable flow section. It also reveals the influence laws on local resistance characteristic of emitter labyrinth channel varying with channel structure, work pressure and water flow pattern. Moreover, the paper analyzes flow cross section of different size and flow channel structures how to impact the drip emitters’ clog, and studies the flow pattern, uniformity of water and anti-clogging properties of drip emitter in the condition of low-pressure. The theoretical and technical foundation will be established for the development and property evaluation of new type emitter.In the aspect of drip emitter’s rapid manufacturing:to construct sets of technology consisted of "integrated" and "split" rapid manufacturing methods, and small quantities rapid manufacturing methods, which can be used for different types of emitter products in fast stereotyping; to systematically analyze the variation lows on the accuracy of emitter structure stereotyping by samples’surface step effects and roughness.In the aspect of the emitter labyrinth channel’s local resistance characteristics:to respectively design and rapid manufacture five products’flow channel structure (tooth channel, rectangular channel, diamond around channel, rectangular around channel and eddy channel) for 1 to 5 channel units; to implement the pressure-flow test under the 9 groups of work pressures; to analyze the impact law of channel structure, work pressure and water flow pattern to the local resistance characteristics. The results indicated that for flow channel with complex shapes should be considered as a whole to calculate the flow of local head loss, after comparing test calculations with the empirical value of the flow structures’local resistance coefficient.In the aspect of emitter structures’influence law on clogging property:to design and manufacture combination channel plates with six kinds of flow structure and 13 kinds of flow section size, and to implement water and strengthen clogging experiments from 16mH2O-2mH2O under the 8 groups of work pressures. The results showed that it can assure 6 kinds of flow channel not clogged when the depth cross-section size is 0.4mm. It will have a good anti-clogging performance when the flow ratio of channel width and depth is more than 2:1.In the aspect of hydraulic performances of drip emitters under low-pressure:to find that compensating function of compensated emitter in low-pressure is worse than that in normal pressure; some compensated emitters’ water uniformity is also poor in low pressures, due to the presence with the critical value of starting water pressure, however, it will agree with that in normal pressure once the pressure exceeds the starting pressure; comparing with the uniformities in the low-pressure has no significant change can be found for those of non-compensating emitters, drip arrows and drip-tapes in the normal pressure. In strengthening clogging experiments, emitters’clogging ratio in low pressures raised greatly compared with the normal pressures. Plastro black emitters, Netafim gray emitters and DaYu triangular drip-tapes, have good anti-clogging property in the low-pressure conditions.In the aspect of new pressure compensated emitter’s rapid manufacturing:to propose a new flow channel structure that can be directly realized the cross-flow section changes with work pressure in the flow channel, thereby achieves the pressure compensation function; to design four different kinds of elastic piece setting methods in the flow channel and rapidly fabricate the test samples of channel amplification model, all pressure - flow experiments have been carried out. The study found that the water flow is least when elastic pieces with the large length are distributed equidistant and interval. Moreover, it has good pressure compensation effect during 4mH2O to 12mH2O pressure range.In summary, the study concerns on the research of rapid stereotyping and rapid manufacturing of emitters’ structure, local resistance characteristics of emitter labyrinth channel, influences on clogging properties that section size and structure of channels have. Low-pressure properties of emitters are also studied deeply. At the same time, a new pressure compensated flow channel structure is proposed. The research achievements will provide significant theoretical basis and technical guidance for the development and manufacturing process choice of new-type emitters with independent intellectual property rights.更多还原