Research On Numerical Simulation And Characteristic Test Of Regulator In Irrigation Pipe Network

Water resource is serious shortage in china,and the proportion of agricultural water is higher.However,the utilization rate of agricultural irrigation water is relatively low.The development of water saving irrigation has important practical significance for agricultural development.Low-pressure pipe irrigation has water saving,land saving and other advantages in many water-saving irrigation technology.Therefore,irrigation pipe network technology has gradually become a key measure for agricultural water saving irrigation in china.How to effectively regulate the pressure is the key to ensure the safe and reliable operation of the pipe network system.Regulator is an indispensable pressure regulating device in pipeline water delivery system.Lack of suitable and reliable regulator can lead to bursting of pipes,water leakage,and system defects.Therefore,the study of the regulator has special significance of safeguarding the safe operation of the pipeline network,improving water efficiency in agriculture,promoting efficient water-saving irrigation in agricultural development.In order to explore the more suitable pressure reducing valve type in large irrigation pipe network.The design of a new type of pressure reducing valve is proposed.The characteristics of regulator were systematically studied by a combination of numerical analysis and testing.The main research contents and achievements are as follows:(1)Improved design of guide valve structure of YX741 type pressure relief valve.This paper explained separately the structural composition and working principle of the two design schemes.Through the analysis of comparison and selection,design plan 2 is selected as the object of numerical simulation and experiment.(2)Using Gambit and CFX software to numerically simulate the overpass flow path of the main valve and the overall structure of regulator.Numerical simulation proved the change law of inlet and outlet differential pressure at different inlet flow rates when the valve opening is 0.8cm,1.0cm,1.2cm,1.6cm and 2.4cm respectively.The results show:When the valve opening is constant,the pressure difference between the inlet and outlet increases with the increase of the inlet flow,and the increasing trend between the different opening degrees is similar.When the inlet flow is constant,the pressure difference between the inlet and outlet decreases with the increase of the valve opening,and the decreasing trend is gradually slow.When the valve opening is 1.6cm and 2.4cm,the two curves are close to coincided.The pressure in the valve increases significantly with the increase of the inlet flow rate.The maximum pressure is at the bottom of the inlet elbow and the lower surface of the valve flap.The maximum flow rate is at the connection between the flap and the outlet.The water flow from the inlet to the outlet is relatively stable,the water flow is relatively smooth,the streamline at the upper part of the valve flap is slightly chaotic,and the flow rate in the pilot valve is small.(3)Numerical simulation proved the change law of driving force of main valve flap at different inlet flow rates when the valve flap at different opening.The results show:When the valve opening degree is fixed,the driving force of the valve flap increases with the increase of the inlet flow rate.However,unlike the change trend of pressure difference between import and export,with the increase of opening,the tendency of increasing driving force tends to be gradual.This shows that the smaller the valve opening,the more obvious the impact of flow changes on the driving force of the valve flap.(4)Through the characteristic test of regulator,the change law of inlet and outlet differential pressure at different inlet flow rates when the valve opening is 1.0cm,1.2cm,2.4cm respectively was proved.Comparing the test results with the digital simulation results,the results show:The test data is generally larger than the numerical results and deviation between 2.8%and 7.9%.Test and verify the accuracy of the numerical simulation results and the feasibility of the method initially.It also provides a reference basis for the development of similar products in the future.