Research On Performance Parameters Of Water-powered Proportional Dosing Pump

Dosing pump is a kind of high-precision and adjustable fertilizer equipment and can work without electricity.The researches of dosing pump,at present,mainly involve performance and new structures but less work mechanism and parameters.There are inadequate theories for designing a dosing pump and most products in Chinese market are imitated because of the lack of design methods.So it is exactly significant to study how to use CFD to simulate dosing pump and research performance parameters.The simulation was about the use of dynamic mesh in fluid-solid coupling and the custom program was compiled based on theoretical analysis and used in the Fluent.Then an experiment about high speed photography was carried out and the feasibility and accuracy of CFD were verified by comparing the results from simulation and test.By simulation internal flow in dosing pump can be observed and forces on piston can be monitored in real time.Then the influence of parameters on hydraulic performance was investigated by simulation or test,inlet and outlet diameter,inlet cavity diameter,drive cavity diameter,inlet valve diameter,outlet valve diameter and stiffness coefficient of reverse spring included.Finally,effect of parameters of suck cavity on performance was studied by experiments.The main research contents and conclusions are as follows:1.UDF was compiled after analyzing the work principle and forces on piston.Then numerical simulation about dosing pump was carried out in Fluent and large amount of flow field data could be obtained by output language.The feasibility and accuracy of CFD method were verified by high speed photography experiment.So it is credible to analyze the internal flow and forces on piston in CFD.The results show that the characteristic of piston includes initial acceleration and constant speed later.Forces on the first and third surface are stable.Force on the second surface increases or decreases first and then remains fluctuation.Error of average flow rate between simulation and test is just 4.20% and error of piston frequency is 20.95%,and the law of movement of both is similar,which indicates that the simulation method is precise.2.Effect of structure parameters on hydraulic performance of dosing pump was researched by dynamic mesh,including inlet and outlet diameter,inlet cavity diameter,drive cavity diameter,inlet valve diameter,outlet valve diameter and stiffness coefficient of reverse spring.It is showed that both average flow rate and piston frequency increase and then become stable as the inlet and outlet diameter increases.Both are the highest when the diameter is 22 mm.Average flow rate is proportional to the inlet cavity diameter.Piston frequency grows and flow pulsation weakens with the increase of diameter.The coefficient is minimal when diameter is 71 mm.As the drive cavity diameter increases,average flow rate keeps fluctuant decline and flow pulsation heightened.The coefficient is minimal when drive cavity diameter is 100 mm.the piston frequency fell and keep constant then with the increase of drive cavity diameter.Average flow rate and piston frequency all grow and become stable then with the increase of inlet valve diameter.The flow pulsation coefficient is minimal when size is 19 mm.Both average flow rate and piston frequency are proportional to outlet valve diameter and flow pulsation is weakest as the size is 12 mm.Stiffness coefficient of reverse spring has no significant influence on hydraulic performance.But starting pressure is higher and allowable pressure is lower when stiffness coefficient decreases.3.The hydraulic performance test table for dosing pumps was built and the effect of suck cavity’s structure parameters on suck performance was researched,including differential pressure,inlet flow rate,cavity diameter,tolerance of fit and stiffness coefficient of spring.The results show that suck flow rate increases and then become stable with the increase of differential pressure and regression model of suck flow rate was built.The suck flow rate is proportional to inlet flow rate and rose sharply when cavity diameter grows.But suck efficiency is higher when cavity size is lower.There is the best performance when interference is 0.5mm and unsuitable interference will cause leak.Stiffness coefficient of spring has no significant effect on the suck performance in a specific range but cannot be larger than a limited value.