| Lotus root is the largest planted area of aquatic vegetables in China,its fertilizer needs a large amount of fertilizer,fertilizer more times,the entire growth period requires 2 to 3 times fertilizer.The special growth traits and environment of lotus root restrict the development of mechanized fertilization of lotus root fields,resulting in a low degree of mechanized fertilization of lotus root.At present,lotus root fertilization is mainly manual spreading of fertilizer,there are problems such as high labor intensity,uneven fertilization and low fertilizer utilization.By combining the agronomic requirements of lotus root fertilisation with the hydrophobic properties of lotus leaves,a hydro-jet type lotus root fertiliser applicator has been designed.,and Theoretical analysis and simulation test analysis,followed by bench and field tests to verify performance,were used to study the key components of the applicator.Details of the study include the following:(1)Determining the physical properties of fertilisers commonly used in rooting.For lotus root fertilisation,three types of fertiliser are commonly used,namely ternary compound fertilizer,large grain urea and potash fertilizer,were studied.Parameters of the physical properties of fertiliser granules such as triaxial size,density,weight per thousand and solubility in water,as well as friction coefficient and collision recovery coefficient between fertilizer granules and materials used in contact with fertilizer applicator were measured,and experimental statistical analysis was conducted to provide necessary parameters for the design,simulating and analysing the performance of structural parameters of fertiliser spreading components.(2)Hydro-jet lotus root fertilizer applicator whole machine design.A hydro-jet lotus root fertilizer applicator is designed according to the actual fertilization requirements of the lotus root field,mainly consisting of a spiral fertilizer supply system consisting of fertilizer tank,drive motor,fertilizer protection pipe and fertilizer supply spiral,and a hydraulic fertilizer application system consisting of a high-pressure centrifugal pump,transmission system,fertilizer suction line,Water and fertiliser hopper,water supply line and spray gun;Key factors in the development of the fertilizer supply performance of the spiral fertilizer supply unit were identified through Theoretical analysis as the speed of the spiral,diameter and conductivity,as well as the range of key parameters of the fertiliser delivery unit;Design and analysis of the fertilizer suction pipeline to determine the parameters of the suction pipeline and the working flow rate,combined with the structural characteristics of the hydraulic lotus root fertilizer applicator,In order to improve the efficiency of the whole machine,the hydraulic calculation method is used to analyse the high-pressure centrifugal pump and determine the transmission ratio of 2.14;Designed a control system for the fertilizer supply device of the lotus root fertilizer applicator,which can adjust the rotational speed of the fertilizer supply screw and thus the amount of fertilizer supplied;The design and selection of the travel chassis and spraying device of the whole machine were carried out.(3)Simulation test analysis of hydrodynamic fertilizer application system.Modeling and simulation experimental analysis of fertilizer supply device and hydrodynamic fertilizer delivery device,respectively.The discrete element simulation analysis of the fertilizer supply performance of the fertiliser supply spiral was made using EDEM,the mean value of fertiliser supply and the coefficient of variation of the stability of fertiliser supply were evaluated using the one-factor test and the regression orthogonal rotation combination test,respectively.The relationships of fertilizer supply screw speed,diameter and guide on the mean value of fertilizer supply and the coefficient of variation of the stability of the fertiliser supply was determined by the single factor test,and the coefficient of variation of the stability of the fertiliser supply under each parameter was less than 7.8%,and the fertilizer supply stability was good;The results of the orthogonal rotation combination test of the regression equation were analyzed and optimized,and in order to determine the significance of the factors,a regression equation has been constructed between the fertiliser supply performance and the factors.affecting the fertilizer supply performance and their interaction terms on the mean value of fertilizer supply and the mean value of fertilizer supply was 329.43 g/s and the coefficient of variation of fertilizer supply stability was 1.43%,which met the agronomic requirements of root field fertilization;The fertiliser delivery performance of the fertiliser suction line was analysed using CFD-DEM flow-solid coupling simulation,and the relationship between the fertilizer delivery performance of the suction line and the fertilizer delivery performance under different fertilizer supply quantities was decisived,and the maximum coefficient of variation of the stability of the fertiliser application was 7.40%according to the amount of fertiliser applied to the lotus field.(4)Experimental study on the performance of hydro-jet lotus root fertilizer applicator.To investigate the working performance of lotus root fertilizer applicator,lotus root fertilizer supply device bench test,Spraying performance Open field test and whole lotus root field test were performed.The results of the fertiliser feeder bench test indicate the following:the actual fertilizer supply performance of the fertilizer supply device is basically consistent with the performance of the simulation test,the fertiliser feeder has good adaptability to the three types of fertiliser commonly used in root zone fertilisation,and the coefficient of variation of the stability of the three kinds of fertilizers at each speed meets the industry standard;The results of the spraying performance open-field test show that the lotus root fertilizer applicator has a spraying range of 28m and a spraying uniformity coefficient of 83.43%under the optimal combination of parameters,which meets the spraying uniformity requirements;The results of the whole lotus root field trial showed that the relative error between the actual and predicted fertiliser application was 3.72%,the uniformity of spraying in the whole lotus root field was 73.53%,the coefficient of variation of spraying uniformity was 31.42%,and the difference between the uniformity of spraying in the lotus root field test and the uniformity of spraying in the open field test was 9.9%,so the whole machine had a better fertilizer application effect. |
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