| Fertilization is an important link in the rice production process.Using lateral deep fertilization technology can save labor and time,reduce environmental pollution,and effectively improve fertilizer utilization rate,which is an important means to achieve cost-saving and efficiency-increasing of rice.At present,there are some problems in the lateral deep fertilization device,such as poor uniformity and stability of fertilization,and easy blockage of fertilizer discharge device due to moisture adhesion,which seriously affects the quality and yield of rice.According to the development status of the lateral deep fertilization device in China and the agronomic requirements of rice lateral depth in the cold region of Northeast China,this paper innovatively designed a disc-type lateral deep fertilization device for paddy field by theoretical analysis,EDEM virtual simulation,DEM-CFD coupling simulation analysis,bench test and other methods,and conducted in-depth analysis and research on its working mechanism and key components,in order to improve the fertilization uniformity of the lateral deep fertilization device for paddy field,alleviate the problems such as fertilizer deliquescence blocking the fertilizer discharge device,and make it practical for paddy field lateral deep fertilization.(1)Selecting the currently used high-speed rice transplanter as the loading object of the fertilization device,the overall structure design scheme of the disc-ejecting lateral deep fertilization device in paddy field was defined.Based on the physical and mechanical characteristics of granular fertilizer for lateral deep fertilization commonly used in rice planting in Northeast China,the key component of the lateral deep fertilization device,the disc-ejecting fertilizer ejector,was designed,and its structure and working principle were expounded.According to the agronomic requirements of lateral deep fertilization and the agricultural technical requirements of fertilizer discharger structure design,various structural parameters are determined,and the theoretical model of fertilizer supply in fertilizer tank was established.Kinematics and dynamics analysis are carried out on the fertilizer filling and discharging processes of the disc ejector fertilizer discharger,and it was concluded that the rotating speed of the fertilizer discharger was an important factor affecting the fertilization performance of the fertilizer discharger.According to the relationship between the volume of fertilizer filling and the rotating speed of fertilizer discharging disc,the theoretical maximum rotating speed of fertilizer discharging disc was 142r/min.Furthermore,the virtual simulation experiment of the fertilizer filling and discharging process of the disc ejector fertilizer distributor was carried out.By analyzing the stress of fertilizer particles during the fertilizer filling process and the change of rotation angle during the fertilizer discharging process,the optimum working speed range of the fertilizer distributor was determined to be 10～60r/min,and the effective working length of the disc fertilizer trough for fertilizer discharging was designed to be 5～20 mm.(2)According to the scheme of auxiliary fertilizer conveying by air in lateral deep fertilization device,the air flow rate,conveying airflow speed and Venturi pipe parameters of the air conveying system were determined.Based on discrete element method and computational fluid dynamics,the mathematical model of gas-solid two-phase flow in fertilizer conveying was established.The DEM-CFD coupling method is used to carry out virtual simulation experiment on the mixing of fertilizer particles and airflow.Under the conditions of pressure inlet airflow speed of 20m/s,25m/s and30m/s,The results of coupling simulation show that fertilizer particles drop 8.3g/s,20.8g/s and33.3g/s respectively,and the movement laws of fertilizer particles and air flow under different working conditions are obtained.It is concluded that the air flow velocity at the pressure inlet was the main factor affecting the movement of fertilizer particles in the fertilizer conveying pipeline,and the air flow velocity at the pressure inlet is 25m/s,which was an ideal working condition for the fan in the deep fertilization operation in paddy field.(3)In order to test the fertilization performance of the disc-ejecting paddy field side-deep fertilization device,the JPS-12 seed metering device performance test bench was used as the carrier,and the discharge consistency,fertilization stability and fertilization uniformity of each row were tested by single factor and multi-factor experiments.The results of single factor experiments showed that the test factors had a significant impact on the discharge consistency,fertilization stability and fertilization uniformity of each row,and the coefficient of variation of each index met the national fertilization machinery operation standard under different rotation speeds of fertilizer discharging discs.The results of multi-factor test show that the order of influence of various factors on the average value of fertilization uniformity was as follows:rotation speed of fertilizer discharge disk,operation speed and wind speed of fan;The influence order of each factor on the coefficient of variation of fertilization uniformity was as follows:operation speed,rotation speed of fertilizer discharging disc and wind speed of fan.The working parameters were optimized by establishing an optimization model.Under the working conditions that rotation speed of fertilizer discharging disc was 10～60r/min,operation speed was 0.7～1.2m/s,and wind speed of fan was 20～30m/s,the average amount of uniform fertilization was 4.0g,The best combination of working parameters is:the rotating speed of fertilizer discharging disc was 10.02r/min,the working speed was 0.82m/s,and the wind speed of fan was 26.16 m/s.At this time,the coefficient of variation of fertilization uniformity was 10.66%,and there was no fertilizer crushing phenomenon in long-time operation.Compared with the existing paddy field side deep fertilization device,it was concluded that the disc ejection type paddy field side deep fertilization device improves the fertilization uniformity.(4)In order to further test the performance of fertilizer amount adjusting device,the effective working length of fertilizer tank was taken as the experimental factor,and the average and total fertilizer amount were taken as the experimental indexes.The results showed that the effective working length of fertilizer tank had a significant influence on the average and total fertilizer amount,and the relationship curve between the total fertilizer amount and the effective working length of fertilizer tank was obtained.In addition,special fertilizers with densities of 1.40g/cm~3,1.30g/cm~3,1.00g/cm~3 and 0.85g/cm~3 were selected for verification test,and it was concluded that the disc ejection type paddy field side deep fertilization device had good adaptability to commonly used special fertilizers,and the variation curve of effective working length and total fertilization amount of fertilizer tank with fertilizer density of 0.85～1.40g/cm~3 was obtained,which could be used for side deep fertilization device. |
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