Design Of Alternate Partial Root-zone Irrigation System And Experimental Study On Its Fluid Mechanism

Currently alternative irrigation equipments have poor water distribution uniformity, complex structure and other issues. Through the laboratory, field experiment, designing alternate irrigation system and distribution valve, adjustable opening irrigation valve in order to ensure the irrigation uniformity. For the convenience of studying, transforming the alternative irrigation water allocation problem into the porous pipe flowing model.(1)Through the comparison and analysis on water capacity of the interval furrow alternative irrigation porous pipe, designing different orifice opening, water head, laying slope, pipe length, the result of the test:The free total flow Qz is always greater than the flow of porousQ0.Changes of laying slope I and hole spacing of S length L, pipeline pressure head H, any one factor will be on a single orifice flow have an important impact, thereby affecting Qo the total discharge of perforated pipe. Along with the pipeline laying length L increases the total flow increases, single hole average flow rate decreases; with increasing pressure head H, the total flow rate and the average single hole flow increased; with the laying slope I increases the total flow and the average single hole flow increased; with the hole spacing S increases, the total the flow is reduced, the average single hole flow increase. Flow reduction coefficient and the number of opening ratio, dimensionless length E, slope ratio between I size analysis of porous pipe, fitting formula.(2) Establishing a mathematical model of variable aperture, variable diameter perforated pipe, and designed them. Using the FLUENT software to study the impact of different inlet velocity, different pore diameter at the end on water distribution uniformity. Results show that variable aperture, variable diameter perforated pipe can improve water distribution uniformity. For the variable aperture perforated pipe, the higher the inlet velocity, the greater the water distribution uniformity; For the PVC pipes of DN25, when the diameter of end hole is10mm, the water distribution uniformity is highest. For the variable diameter perforated pipe, the lower the inlet velocity, the greater the water distribution uniformity; The smaller the aperture at the end, the greater the water distribution uniformity.(3) Having researched and designed the adjustable opening irrigation valve and alternate irrigation distribution valve. The calculation of adjustable open relation degree of irrigation valve rotation number and water area, and used to guide irrigation, application of FLUENT software to simulate the adjustable outlet at different opening, flow characteristics under different water head. Application of adjustable outlet and alternate irrigation distribution valve, builds single and double pipe two alternate furrow irrigation system, used for field test, results show that can guarantee the uniformity of irrigation water.(4) Build the core of micro irrigation system with microtubule and greenhouse vine climbing rope, and planning and design. To the cultivation of cucumber as an example, according to the different cucumber growth period irrigation quota, germination stage, seedling stage0.13L/strain0.227L/strain,1.53L/strain, the early flowering period2.56L/strain. Hydraulic characteristic analysis for all levels of the pipeline system, the test and calculation system supervisor of (p32plastic pipe, pipe selection of φ16hard plastic tube, core microtubule core material selection of polypropylene rope permeability coefficient K=0.249. Through greenhouse experiment area and conventional furrow irrigation and drip irrigation on irrigation uniformity, it is concluded that the system is up to93.3%, the core of microtubule irrigation efficiency than the conventional96.6%, the effective irrigation rate of80.5%increased by20%. Unit area investment is280yuan/mu, with good economic benefit.