| The integration of water and fertilizer has the advantages of saving water,fertilizer and labor,and has been widely promoted in the northwest region where water resources are scarce.Among them,the proportional fertilizer pump matched with drip irrigation system has stable operation,high fertilizer uniformity and better performance.At present,the fertilizer performance of the fertilizer pump has been tested and studied separately.On the premise of keeping the first pressure of drip irrigation belt unchanged,the performance test of the hydraulic proportional fertilizer pump was carried out.The effects of the pressure difference between the two ends of the fertilizer pump,the ratio of fertilizer absorption,the different ratio of fertilizer and liquid in the fertilizer barrel on the amount of fertilizer absorption and the concentration of fertilizer and liquid in the fertilizer application pipeline and water delivery pipeline were analyzed.After the preliminary optimization scheme is arranged in the field test drip irrigation system in Wuwei area,through the field corn water-fertilizer integrated drip irrigation experiment,the pressure difference between the two ends of the fertilizer pump and the inlet flow rate,the amount of fertilizer absorbed,the concentration of fertilizer solution and the proportion of fertilizer absorbed are comprehensively analyzed,and the numerical simulation experiment is carried out with FLOW-3D software,and the suitable combination mode of operation parameters is selected for irrigation and fertilization.Through the above research and analysis,the following conclusions are drawn:(1)Under the designed flow range,the amount of fertilizer absorbed basically accords with its corresponding proportion,and the change of fertilization proportion has little effect on the inlet flow.When the pressure difference between the two ends of the hydraulic-driven proportional fertilizer pump is small and the proportion of fertilizer application is large,the stability of the fertilizer pump is not as good as that of other fertilizer application proportions.When the pressure difference is between 0.02 MPa and 0.035 MPa,the operation performance of the pump is the most stable.With the increase of the pressure difference,when the pressure difference exceeds 0.05 MPa,the phenomenon of fertilizer withdrawal will occur.Therefore,it is not recommended to adopt excessive pressure difference and small fertilization proportions in actual production.Fertilizer combination.(2)In field experiment,the flow rate of fertilizer pump increases with the increase of the first pressure of drip irrigation belt.Under the same pressure head,the flow rate increases little with the increase of the proportion of fertilizer absorption.In field experiment,the amount of fertilizer absorption under the same pressure head increases with the increase of the proportion of fertilizer absorption,which basically accords with the corresponding proportion of fertilizer absorption;when the proportion of fertilizer absorption is 4%,the two types of drip irrigation belt There is a certain degree of blockage.It is suggested that a large proportion of fertilizer should not be applied in actual production.(3)The stability of the lateral labyrinth drip irrigation belt is not as good as that of the internal patch drip irrigation belt.It is not appropriate to choose the lateral labyrinth drip irrigation belt with a larger proportion of fertilizer absorption and a higher head pressure.The proportion of fertilizer absorption should not exceed 3%when the pressure at the head of the pipeline is large.Under the same inlet flow rate,the larger the proportion of fertilizer absorption,the smaller the relative deviation between the measured value and the set value of the corresponding amount of fertilizer absorption and the input flow,and the actual required fertilization time increased by nearly 1/4 compared with the set time,which was basically consistent with the previous indoor test results.In the actual production and operation,the appropriate proportion of fertilizer absorption and the head pressure of the irrigator should be matched to meet the requirement of fertilizer application on time.(4)A numerical simulation model of hydraulic driven proportional fertilizer pump was established.The reliability of the simulation results was verified by comparing and analyzing the relationship between inlet flow rate and pressure difference.The maximum relative error was 7.22%.This shows that the simulation test method is more accurate and the model is reasonable.It can be used to effectively simulate and analyze the liquid flow in the subsequent fertilizer pump.The piston up-going time is 13%~21%longer than down-going time in each proportion of fertilizer absorption.The piston running time of fertilizer pump decreases with the increase of the proportion of fertilizer absorption.Because the velocity of flow in the pump body decreases sharply at the inlet end and increases at the outlet,the downgoing time of the same stroke is less.(5)With the design of improved fertilizer barrel,the resultant force of driving piston to the top of the pump body in vertical direction increases with the increase of pressure difference,and with the increase of pressure difference,the speed of increasing is faster and faster,reaching a stable state in about 2s,and the fertilizer density at the outlet is about1.05g/cm~3when the fertilizer barrel is stable;the flow rate of fertilizer liquid in fertilizer barrel increases from top to bottom,and from around to center.The maximum flow rate at the outlet of the fertilizer solution in the suction pipe is 1.10 cm/s.Compared with the traditional fertilizer barrel,the residual amount of fertilizer solution in the improved fertilizer barrel is reduced by 79.2%.The utilization rate of fertilizer solution is effectively improved,and the problem of fertilizer dissolution is improved,which achieves the effect of saving time and labor. |
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