Research On Hydraulic Properties And Rapid Manufacturing Methods Of Drip Emitters

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.