Design And Verification Of Efficient Irrigation System With Mixed Fertilizer In Integration Of Water And Fertilizer In Orchard

China is the country with the largest orchard planting area and fruit output in the world.Fruit production plays an important role in Chinese agricultural production.However,in the process of orchard management,the application of water and fertilizer is large and the use efficiency is low.China is a country with relatively insufficient water resources.To save water and fertilizer and improve the efficiency of water and fertilizer use has become one of the most urgent problems in fruit industry.Water and fertilizer integrated irrigation technology is one of the means to solve the above problems,but this technology also has the problem that fertilizer dissolution is not complete,and the sprinkler is easy to be blocked.In this paper,a set of integrated water and fertilizer efficient mixed fertilizer irrigation system for orchards is developed by means of computer numerical simulation technology,and field experiments are carried out.The research contents and main conclusions are as follows:(1)By analyzing and comparing the flow patterns of different agitators,a new type of right-angle folded-blade disc turbine agitator is designed.Orthogonal experiment is used to optimize the mixing rod of the new agitator.The deformation and stress values calculated by ANSYS simulation are used as evaluation indexes,and the influence of the diameter,length and quantity of the agitator rod on the corresponding indexes is obtained.Finally,the optimum working parameters of the mixing rod are determined as follows: the diameter of the mixer is 30 mm,the length of the mixer is 300 mm,and the number of the mixing rods is 8.(2)Modal analysis of the optimized agitator shows that the main frequency of the lowest order mode is 19.13 Hz,and the frequencies of each order are much higher than those of the external excitation source of the fertilizer mixer,showing good vibration characteristics.The agitator is simulated by FLUENT to analyze the velocity vector and velocity gradient distribution under different rotational speeds,and to study the influence of agitation speed on the flow field distribution.At present,when the rotational speed is less than the critical stirring speed,the flow pattern of the agitator is single and the turbulence distribution is less,so it is not conducive to the dissolution of fertilizer,which verifies the accuracy of the theoretical calculation of the critical stirring speed.When the rotating speed is higher than the critical stirring speed,the velocity vector distribution in the rotating stirring process is more complex.The flow field of the agitator produces more turbulence and disturbance,which can effectively improve the effect of fertilizer mixing.At the same time,it is found that when the rotating speed is higher than the critical stirring speed,the increase of the stirring speed has less influence on the flow field distribution in the mixer.On the premise of reducing the working energy consumption,stirring and the number of bubbles produced in the mixing process as much as possible,the optimum mixing speed of the new mixer is 600r/min.Besides,based on STM32F407ZGT6 MCU and Lab VIEW,the hardware and software of the system are designed,and the integrated irrigation control system of water and fertilizer is built.(3)With Box-Behnken experimental design method,a quadratic regression model indexed by undissolved amount of three fertilizers is established.Through the interaction of the model and the analysis of response surface,the influence of stirring speed,stirring time and submerged depth of stirrer on response index is obtained.The model is optimized by using the optimization function of Design expert.The optimal combination of working parameters is: stirring speed 600r/min,stirring time 5min and submerged depth 660 mm,which verifies the accuracy of simulation results and the rationality of mechanical design and calculation.At the same time,the comparative experiment of the fertilizer dissolving ability of the new type agitator is carried out,and its promoting effect on water and fertilizer dissolution is verified by comparing with the propeller agitator in common use.Under the same stirring parameters,600 g,800g,1000 g ammonium bicarbonate,compound potassium fertilizer,mixed soluble phosphate fertilizer and 100 L clear water mixed solution are stirred respectively.From the result data,it can be seen that the new agitator the new agitator can solve the problems such as insolubility of fertilizers or insufficient dissolution of fertilizers due to other reasons and has better adaptability and can better promote the dissolution of fertilizers.