The Fluid-solid Coupling Numerical Simulation And Experiment Research Of Pressure Regulator For Micro Irrigation

Pressure regulator is one of the most important equipments in micro-irrigation systemand it’s widely used in agricultural irrigation. The outlet pressure remains stability while theinlet pressure changeds by the use of pressure regulator. So far, there are little researches inthe regulation mechanism of pressure regulator in our country. And the study of the innerflow regime of the pressure regulator is rarely concerned. The numerical calculation, realizedby numerical simulation software, for regulation process of pressure regulator is adopted toanalyze the internal flow field distribution of regulation process and to make sure themovement of each component, which is of great guiding significance for the research anddevelopment of pressure regulator. In this paper, the spring-loaded and the diaphragm-springpressure regulators are selected as the research object. The research of the pressure regulationprocess has been made by the methods of fluid-solid coupling numerical simulation combinedthe sample experiments and the regulation principle of pressure regulator has been furtherdiscussed.The main conclusions are as follows:(1) Compared the results got by simulation with experiment, it can be found that theoutlet pressure and flow volume got through the fluid-structure interaction and experimentwas basically identical, the average relative bias error for pressure and flow volume waswithin10%. This verified that the viability of the fluid-structure interaction method in thestudy of direct-acting pressure regulator during the pressure adjusting process.(2) After the numerical analysis of regulation process of the direct-acting regulator，it canbe found that the flow field evenly distributed when the inlet pressure is less than the initialregulating pressure. The eddy area increased as well as the velocity around it when inletpressure reached the initial regulating value. The maximal velocity took place in the back sideof regulating part and increased with the inlet pressure. The regulating components began tomove along axial direction and the pressure differentials gradually increased when the inletpressure of pressure regulator reached the initial regulating pressure. The moving speed ofregulating part is fast as the inlet pressure stays between initial pressure and steady regulating pressure. When the inlet pressure reaches the steady value, the axial displacement of theregulating part increased with the inlet pressure and finally stabilized undulatingly with thevalues from13to13.8mm, which can stabilize the outlet pressure.(3) Comparing the results of three-dimensional fluid-structure interaction calculation ofthe diaphragm-spring pressure regulator with the hydraulic performance, the relative biaserror for pressure was within4%and flow volume was within10%. This verified that theviability of the fluid structure interaction method in the study of diaphragm-spring pressureregulator during the pressure adjusting process.(4) The axial displacement of regulating part was small before the inlet pressure ofpressure regulator increases to115KPa, but the deformation of elastic diaphragm was obviousdue to the effect of the hydraulic pressure. The displacement increases gently at the process oftheir reaching to the regulating pressure. The axial displacement of regulating part and elasticdiaphragm rapidly increased when the inlet pressure reached the regulating value, whichincreased from1.59E-05m and0.5mm to3.77mm and3.58mm. The rate reached the extremevalue when the inlet pressure was118KPa and then decreased. The pressure loss occurredmainly in the regulating part before the inlet pressure reached regulating value, and thenoccurred mainly between the regulating part and the block cap during the steady workingstate.