Design And Hydraulic Performance Research Of The Emitter And Pressure-Regulator Based On The Venturi Principle

For the problem of lake of low-pressure irrigation emitter and pressure regulator indomestic, a kind of emitter and pressure regulator based on the Venturi principle wasdesigned. The emitter experiment based on vertical intersection design of4factors and3levels were carried out, and experimental research and analysis of hydraulic performancewere carried out to the emitters of the different structural parameters. This paper designed apressure regulator based on CFD, which simulated channels of different structural parameters,and analysis the hydraulic performance of flow paths with different cross-sectional areas andshapes. Pressure regulator RP products were maked and verification tests of hydraulicperformance were carried out. Through research and analysis, some basic conclusions drawnare as follows:(1)The result shows that the sequence of importance that structural parameters effecton discharge exponent is outlet diameter, return tube diameter, and contraction taper andthroat diameter. The most superior partner is throat diameter of2mm, contraction diameter of1.16rad, returning tube diameter of6mm, and outlet diameter of3mm. The standarddeviation analysis shows that the effect of the outlet diameter and returning tube on dischargeexponent is significant. A model was established between structural parameters and hydraulicperformance parameters according to the linear multivariable regression method, the functionscould be used on parametric design of the Venturi emitters. The analysis between structuralparameters and hydraulic performance parameters could provide a theoretical basis for furtherstructural optimization of emitter.(2)Vertical intersection design and computational fluid dynamics soft ware Fluent6.3were adopted to simulate the flow of Venturi pressure regulator. The results show that thesequence of importance that structural parameters effect on discharge exponent is shuntsegment diameter, throat diameter, return tube diameter, and contraction taper. the sequenceof importance that structural parameters effect on discharge is throat diameter, shunt segmentdiameter, contraction taper, and return tube diameter. The impact of key structural parameterson discharge exponent and flow discharge was analysed using variance analysis, the resultsshow that the throat diameter is the important factor affecting the discharge. According to thelinear multi variable regression method, models of discharge exponent and discharge with structural parameters was established,the linear multivariable regressions provide a theoreticalbasis for the Venturi pressure regulator structure design and quantitative analysis. Thepressure distribution and velocity distribution fully reflected the energy dissipation effect ofVenturi principle, the pressure regulator has the dynamic adjustment effect.(3)Experiments have been taken on the comparison of two different kinds of pressureregulators under three different conditions. The two kinds of pressure regulators are withreturn tube and without tube. The three different conditions differ from each other at the partthat behind the pressure regulator, with pressure, without pressure, with emitter. For thecondition that without pressure, flow rate simulation with CFD is similar with theexperimental result. The mean relative error for flow rate is7.78%, which means thesimulation is with high precision. The simulation method can be used to study the relationshipof structure and performance of the pressure regulator, to optimize the structure of thepressure regulator. In this way, we can reduce the work for the experiment and decrease thecost. In the experiment, the flow rate of sample1is33.3%less than sample2, which meansthe return tube of sample1works.Under the condition that without pressure, the experimental result shows that thepressure for the part behind the return tube is larger that the part of throat. So water can goback through the return tube, and also the subpressure of the throat part changes with the inletpressure. Experiment results show that the pressure decrease of the regulator with return tubeis7.42%higher than the regulator without return tube. The relationship between head loss ofreturn tube and inlet pressure indicate that when the inlet pressure go up, the head loss in thereturn tube increase, the velocity head increase, the flow rate increase. The theory of this kindof pressure regulator is taking advantage of the return tube, as there is a difference of pressurearound the return tube. The higher of the value of the difference, the subpressure of the throatpart is larger, the water that goes back is more. What's more, the performance of the regulatoris much better. The pressure regulator can regulate the pressure during the whole procedure.