Study On Pressure Fluctuation Of Diaphragm Pump Spraying System

Variable application of pesticides to improve the utilization rate of pesticides and reduce the pollution of foods and the environment caused by pesticide residues is the development direction of pesticide application.However,the intermittent suction and drainage characteristics of the diaphragm pump in the variable application system and the high-speed opening and closing of the solenoid valve lead to a larger pressure fluctuation range in the application system,thereby affecting the atomization characteristics of the nozzle and the control accuracy of the spray flow rate.In this paper,the fluctuation characteristics of the main source of pressure pulsation in the pipeline of the variable drug application system are studied.The FSI module under Workbench software is used to perform bi-directional fluid-solid coupling simulation of the dynamic changes of the internal flow field during the operation of the diaphragm pump.Diaphragm pump outlet pressure pulsation value,pressure chamber diaphragm deformation,and in the existing PWM variable application system performance test bench diaphragm pump outlet pressure dynamic characteristics test,verify the accuracy of the simulation model and the reliability of the simulation results.The main work and conclusions of the paper are as follows:(1)First of all,the status of domestic and foreign research.According to the research status of variable spraying and the large fluctuation of pressure in the PWM variable spraying system,the research contents of this paper are put forward according to the research status of the output pressure pulsation of the reciprocating diaphragm pump.(2)The working principle and internal structure of ZMB240 piston diaphragm pump are analyzed,and the inlet speed of the diaphragm pump is simplified on the basis of accurate and true reflection of the pressure fluctuation of the diaphragm pump.At the same time,the nozzle of the spray system,proportional relief valve Simplification,and finally get a simplified model of CFD simulation of diaphragm pumps,simulation model upstream water speed entrance UDF program.(3)Based on the FSI fluid-solid coupling module of the Workbench,the three-dimensional bi-directional fluid-solid coupling simulation of the liquid field,the gas domain and the rubber diaphragm of the diaphragm pump is carried out to analyze the stress and deformation of the upper and lower surfaces of the diaphragm under the initial pressure of the different pressure chamber.Stress is about 4 times the minimum stress,the upper edge of the diaphragm for the stress concentration area,the regulator chamber design of the relevant views,while monitoring the diaphragm pump a cycle of export flow,and manufacturers to provide data comparison,verify the simulation The accuracy of the model.(4)Based on the analysis of the fluid-solid coupling of the diaphragm pump,a further analysis of the output pressure pulsation of the diaphragm pump is put forward,and a simplified three-dimensional finite element analysis of the ZMB240 piston-type diaphragm pump without stabilizing gas chamber is put forward The simulation results show that the output pressure fluctuation of the diaphragm pump is monitored and compared with the results of the initial pressure condition of the gas chamber diaphragm pump.The results show that the diaphragm pressure regulator chamber The presence of the chamber structure can reduce the pressure of the diaphragm pump output pressure,but the initial pressure of the regulator chamber must match the working pressure of the diaphragm pump in order to achieve a good regulator effect,the initial pressure is too high or too low will affect the regulator Air chamber regulator effect.(5)The effect of different spray pressure on the output pressure pulsation of the diaphragm pump is studied by using the CFD simulation model of diaphragm pump to control the different parameters(volume,initial pressure,diaphragm elasticity model)and the spraying pressure of the diaphragm system.The results show that the diaphragm pump elastic modulus of the diaphragm is E=15MPa,the volume of the chamber is V=320000mm~3,and the output pressure pulsation pulsation is 11%.The fluctuation of the output pressure of the membrane is not linear with the initial pressure of the regulator chamber.So that the pressure fluctuation of the smallest steady pressure chamber initial pressure.