Theoretical And Experimental Research On Valve Regulating Proportional Fertilizer Injector

The valve regulating proportional fertilizer injector is a kind of quantitative fertilization devices with mall size,simple operating procedure,low start pressure,constant and adjustable fertilizer concentration,no external power and low price.It has very high value of popularization and application,but the fertilizer bottle is of small volume,so it requires frequent replacement.At present,there are few researches on the valve regulating proportional fertilizer injector in China.Therefore,it is of high academic and practical significance to study the performance analysis and optimization design of the fertilizer injector.In this paper,the operation mechanism of the fertilizer injector is deeply analyzed by means of theory,test and simulation.The force formula of the piston and the fertilizer ratio formula are obtained.The hydraulic performance experiment is carried out and the main performance curve of the fertilizer injector is obtained.The part of fertilizer container is improved to realize higher fertilization efficiency and lower fatten frequency.The flow regulation principle and hydraulic performance of the three way regulating valve are studied.The UDF is compiled to dynamic grid simulation and the motion and force of the driving piston are analyzed.The main contents are summarized as follows:1.Operation mechanism introduction and theoretical analysis.The structure and principle of the valve regulating proportional fertilizer injector are introduced in detail.The actuating mechanism and running state of the left and right motion of the driving piston and the fertilizer piston are analyzed.The force formula of the piston and the fertilizer ratio formula are obtained.The result shows that the driving piston is subjected to the pressure difference between two sides,the friction force from the shell,the resistance of the piston and the reversing mechanism during the running process.The proportion of fertilization is directly proportional to the square of the ratio between the diameter of the driving piston and the sucker piston,and is proportional to the horizontal shunt ratio of the three-way valve.2.The test of hydraulic performance and the improvement of the storage portion structure.The experiment bench is built to test the hydraulic performance of the fertilizer injector.The pressure flow curve,flow angle curve,piston motion frequency curve and the fertilizer ratio curve are obtained.The storage portion is transformed from a small-volume bottle into a large-capacity fertilizer tank.The hydraulic performance test of the improved fertilizer injector is carried out and the experimental results are compared with those before improvement.The results show that the inlet flow rate of the fertilizer under the same pressure increases first and then decreases with the increase of the angle of the three-way valve.The motion frequency of the piston increases with the increase of the angle of the three-way valve in general,but the trend is wavy in the middle part and the maximum value is 0.35%.The improvement of the fertilizer storage part improves the hydraulic performance of the fertilizer applicator.3.Study on the performance of three-way flow regulating valve.Theoretical analysis of the flow area of three-way valve is carried out and the theoretical formula and curve of the horizontal shunt ratio are obtained based on the principle of the regulating valve.The hydraulic performance experiment of three-way valve is carried out,and the flow-angle curve and horizontal shunt ratio curve which verifies the correctness of the formula are obtained.The internal flow of three-way valve is numerically simulated,and the accuracy of the simulation is verified by experimental results.The results show that the area change of the import and export of the three-way valve is rotated and symmetrical.The theoretical curve of the horizontal shunt ratio is a rotation-symmetry curve about the point(45 °,0.5)whose general trend is upward although with fluctuates in the intermediate range.The inlet flow curve of the three-way valve is mainly related to the inlet flow area curve of the three way passageway.The accuracy of the fertilization ratio formula is verified because the fertilization ratio curves with test,simulation and theoretical three-way valve diverting ratio data are small deviated with each other and same trended.4.Driving piston motion process simulation.The simplified simulation scheme of the fertilizer injector is designed and the UDF program is compiled into the dynamic grid technology in Fluent to simulate the fertilizer injector,and the force and speed of the piston driven by the left and right pressure are effectively understood.The key performance curve and internal flow situation of the fertilizer injector are obtained and the simulation reliability is verified by experimental results.The force and speed curve of the driving piston are analyzed,and the result shows that the driving piston is accelerated at the beginning of motion and quickly reached a uniform speed.In the course of actual operation,the driving piston was also subjected to resistance from the shell,the sucking mechanism and the reversing mechanism,so there was a deceleration process after the uniform speed process.