Study On The Hydraulic Of Pipe Networks In Subsurface Drip Irrigation

Subsurface drip irrigation (SDI).which has more effective in water-saving, has been paid more attention by researchers all over the world. But the study on the hydraulic of pipe networks in SDI is still faultiness. Field experiments and mathematical model combined to analyze hydraulic effects of compression deformation of subsurface drip-tapes. And the hydraulic relations among kinds of pipeline networks were studied in this paper. The experimental and analytical results indicated:1. Hydraulic considerations for compressed subsurface drip-tapeReduction in average emitter flow rate corresponds to the degree of drip-tape deformation, resulting from soil compaction, and to the inlet flow rate. The effects of less 50% compression on inlet flow are less critical. The recommended maximum lateral length should be reduced based on corrected coefficient a, in ,and times of irrigation lengthened, according to the degree of anticipated compression of the drip-tape.2. Pressure distributing in the submainPressure distributing in the submain of such three pipe networks, branched networks, single flushline looped networks and double flushline looped networks are the same. Increase in pressure in the submain corresponds to the increase in the main. The pressure curve is exponential. In the pipe networks which used compensated emitters, as pressure increasing in the main, the pressure in the branched networks tends to a jarless range. Whereas the pressure in the other two looped networks differ from it. The equation relations between inlet flow and pressure in the submain of all the pipe networks are multinomial.3. Hydraulic relations between the looped networks and the branched networksIn the pipe networks which used noncompensated emitters, the inlet pressure in capillaries in the looped networks are higher than those in the branched networks. The inlet flow in capillaries in the three pipe networks are approximately identical, the diversifications of flux are in 7%. About uniformity, emitter's discharge in the looped networks are better than those in the branched networks. And it is obviously under the low work pressure. In the pipe networks which used compensated emitters, the inlet pressure in capillaries in the looped networks are lower than those in the branched networks. The inlet flow distributing in capillaries in the three pipe networks are similar to the pressure. In the tested pressures, the branched networks showed the pressure compensate function, whereas the function of the looped networks is lagged behind the branched. The uniformity on the capillaries inlet flow, the looped networks are better than the branched.4. The optimal design of pipe networks in SDIBased on above experiments, a method of the numerical simulation for optimal designing pipe networks in SDI is presented. And it is solved with node hydraulic pressure procedure. Results showed that it is viable and feasible. With the model combing corrected coefficient a, m,the optimal design of looped networks in SDI was simulated, and to provide a reference for designing and running a SDI system.