Design And Performance Research On Bubbled Root Irrigation Emitter In Different Pressure Unit

Based on the guiding thought of bubbled-root irrigation and mountain pressureseparation, on the one hand, the effect of the sediment size on the emitter anti-cloggingperformance was studied, and the sensitive sediment size which is easy to cause clogging wassearched and the proper filtration measure was been proposed through the method of similarshort cycle anti-clogging test and interval muddy water irrigating in this article. On the otherhand, In order to design and develop new pressure compensating bubbled-root irrigationemitter which were used in different pressure unit, the large labyrinth was combined to theprinciple or pressure compensating, and the method of Pro/E three-dimensional drawingsoftware、numerical simulation, Rapid proto-typing technology and hydraulic performancetest were adopted in this study. The effect of structure parameters of the pressurecompensating area on the hydraulic performance of the emitter was discussed, which canprovide guidance on the pressure compensating emitter design. The main conclusions are asfollows:(1) The three mountain micro-irrigation pressure partitions and the selected emitter ineach area had been determined like this: low pressure area (0~8m), medium pressure area(8~25m), high pressure area (25~40m). The existing large labyrinth bubbled-root irrigationemitter was determined to be used in Low pressure area. The buried pressure compensatingbubbled-root irrigation emitter which was needed to design and developed in this study wasdetermined in the middle pressure area and the high pressure area. The massive structure ofthe buried pressure compensating bubbled-root irrigation emitter was designed in this chapter.(2) Under the condition of this experiment, the sediment concentration did not causeobvious effect on the clogging of the large labyrinth bubbled-root irrigation emitter. Theclogging process of the emitter occurred repeatedly, and the sudden and complete cloggingmainly occurred on the sediment water which the sediment size is more than0.1mm. therepeated and partial clogging mainly occurred on the sediment water which the sedimentsize is less than or equal to0.1mm. The clogging sensitive sediment size of the large labyrinthbubbled-root irrigation emitter was0.1-0.15mm, which should be removed in real irrigation.The measurement, such as deploying grit chamber, proper filtration before irrigating, washing the irrigating system after irrigating and designing a new washing back bubbled-rootirrigation emitter were used to promote the clogging problem.(3) There are more the50%of the total sand weight depositing in the lateral, so thesand deposition in the lateral was one important reason for the emitter clogging. When thesediment is larger than0.058mm, the sand deposition distributed unequally in each lateral, thefirst lateral is more than any lateral, and the sand deposition of the second lateral was second.When the sediment is smaller than0.058mm, the sand deposition in each lateral distributeequally. Not only the ability of transporting sand was affected by the sediment concentrationand size, but also by the sand deposition in laterals. The ability of transporting sand increasedalong with the increase of the sediment concentration and irrigating times, and reduced alongwith the increase of the sediment size.（4）The pressure compensating bubbled-root irrigation emitter which was appropriatefor middle pressure area and high pressure area were developed, the key structure parametersand the hydraulic performance were as follow: middle pressure area: the thickness of theelastic membrance is1.5mm, the hardness of the elastic membrance is50, the boss height is3mm, the discharge exponent is0.038, the rated flow is8.55L/h, the pressure compensatingarea is6-32m. High pressure area: the thickness of the elastic membrance is1.9mm, thehardness of the elastic membrance is50, the boss height is3mm, the discharge exponent is0.066, the rated flow is8.36L/h, the pressure compensating area is24-40m.（5）through the analysis of the effect of the key structure parameters on the emitterhydraulic performance, we could see that the flow rate of this kind of emitter increased alongwith the working pressure at relatively low pressure; when the pressure was appropriate, theflow rate would keep similar even if the pressure increased; when the pressure was high, theflow rate of this kind of emitter would reduced along with the working pressure. In middlepressure area, the order of the effect of the key structure parameters on the discharge exponentwas the hardness of the elastic membrance(B), the boss height(C), thickness of the elasticmembrance(A); the order of the effect of the key structure parameters on the rated flow ratewas the hardness of the elastic membrance(B), thickness of the elastic membrance(A), theboss height(C). In high pressure area, the order of the effect of the key structure parameters onthe discharge exponent and the rated flow rate was the hardness of the elastic membrance(B), the boss height(C), thickness of the elastic membrance(A). These conclusions can provideguidance for the design and development of pressure compensating emitter.