| Rice is one of the most important food crops in the world,and plays an important role in ensuring world food security.However,the growth rate of grain production is not in direct proportion to the growth rate of chemical fertilizer input.The phenomenon of excessive use of chemical fertilizer is relatively serious.The unreasonable use of chemical fertilizer not only increases agricultural production costs and wastes resources,but also easily causes problems such as soil acidification and hardening.The lateral deep fertilization technology for rice is a scientific fertilization management and technical system proposed for the irrational use of fertilizer,which can promote the growth and development of rice seedlings,improve fertilizer utilization efficiency,achieve cost saving and efficiency improvement,and reduce environmental pollution.The lateral deep fertilization device for rice is the carrier of its application.There are problems such as insufficient fertilization stability and uniformity,limited fertilizer adjustment capacity,and unclear optimal conveying wind speed of the air conveying system,which directly affect the quality of the lateral deep fertilization operation.In order to solve the above problems,this paper carries out the innovative design and working mechanism research of conical disc push plate type side deep fertilizer application device based on the agronomic requirements of side deep fertilizer application in northern cold rice crop area,the main contents are as follows:(1)Referring to the characteristics of the domestic and foreign deep fertilization device and the agronomic requirements for deep lateral fertilization in the northern cold rice farming area,taking the common special fertilizer for deep lateral fertilization of rice as the research object,selecting the common high-speed rice transplanter as the carrying object,clarifying the overall design scheme of the conical disk push-plate deep lateral fertilization device according to the design requirements of the fertilizer discharger,adopting the horizontal mechanical structure for fertilizer discharge operation and assisting fertilizer delivery through positive pressure air supply.The overall structure and working principle of the device are described in detail to provide reference for the innovative design of the fertilizer discharger.(2)According to the range of agronomic requirements of 150～930 kg/hm~2 fertilizer application rate in the northern cold region,a mathematical model of fertilizer application rate in a single circle of the conical disc push-plate fertilizer discharger was established.It was determined that the horizontal outer diameter,horizontal inner diameter and horizontal height of the conical turntable of the fertilizer discharger were 208 mm,158 mm and 7.5 mm respectively.Based on the theoretical analysis of the material flow characteristics and the continuous and stable working conditions of the fertilizer discharger,the number of push plates is determined to be 8 according to the discrete element simulation results.Based on the theoretical analysis of the key components of the conical disc push-plate fertilizer discharger with the method of dynamics and kinematics,the mechanical model of fertilizer particles in different working links of the fertilizer discharger was constructed,and the inclination angle of the conical rotary table was determined to be 28°.The theoretical maximum rotational speed of the conical rotary table was 146 r/min,and the minimum rotational speed of the conical rotary table was 13 r/min,and the rotational speed range of the conical rotary table was determined to be 15～45 r/min according to the requirements of agricultural fertilizer application.According to the continuous discharge conditions of fertilizer particles,the designed width of fertilizer retaining blade and fertilizer discharge width are 25mm.The discrete element method is used to simulate the effect of fertilizer discharge pipe on the transport law of fertilizer particles and the fertilizer discharge performance.The results show that the fastest curve type fertilizer discharge pipe has obvious acceleration effect on fertilizer particles and the minimum variation coefficient of fertilizer particle mass flow,which effectively improves the fertilizer discharge performance of the fertilizer discharge pipe of the fertilizer discharge device.(3)Taking the pneumatic fertilizer conveying system device as the research carrier,based on the requirements of the paddy field side deep fertilization operation,the physical characteristics of fertilizer particles and the theoretical analysis of gas-solid two-phase flow,the structural parameters and distribution scheme of the system components were determined,that is,the conveying air volume of the system was 268.125 m~3/h,the conveying air velocity was 19.72 m/s,the inner diameter of the inlet and outlet of the three-way pipe was 29 mm,the inner diameter of the fertilizer inlet was 25 mm,the inner diameter of the three-way pipe at the fertilizer inlet was 25 mm,and the contraction angle was 21°.The throat diameter is 13 mm and the overall length is 248 mm.Divide the fertilizer discharge pipe grid,carry out the coupling simulation test of fertilizer particle transport process based on CFD-DEM gas-solid coupling method,and determine the best fertilizer transport airflow velocity under different fertilization rates.Under the corresponding optimal airflow velocity conditions,the transport state of fertilizer particles is basically the same,showing a change rule from sliding along the bottom of Venturi tube to suspension,and the fertilizer particle velocity gradually increases.The mathematical model of fertilizer transportation rate and optimum air flow rate is established,which provides reference for the follow-up experimental research.(4)In order to verify the working performance of the lateral deep fertilization device,the lateral deep fertilization device was installed on the JPS-12 type seed metering performance test bench to carry out the fertilization performance test.Through the factorial test,the effects of the rotating speed of the cone turntable and the opening of the fertilizer discharge mouth on the fertilization amount,the double-row consistency variation coefficient,the fertilization stability variation coefficient and the fertilization uniformity variation coefficient were obtained.The results showed that the rotating speed of the cone turntable and the opening of the fertilizer discharge mouth had a good correlation with the fertilization amount.It has no significant effect on the coefficient of variation of double-row consistency.The maximum value in horizontal condition is 3.88%,and the maximum value in inclined condition is 6.17%.It has a significant impact on the coefficient of variation of fertilization stability,and the maximum value predicted by the model is 3.88%.It has a significant impact on the coefficient of variation of fertilizer uniformity,and the maximum value predicted by the model is 15.31%,which meets the national standard for fertilizer machinery operation.At the same time,the overall performance of the conical disc push plate side deep fertilization device was tested on the bench.A three-factor and three-level orthogonal combination test was carried out to establish a regression model between the conical rotary table speed,the opening of the fertilizer discharge mouth,the forward speed and the variation coefficient of fertilizer uniformity.It was found that the influence degree of each factor on the variation coefficient of fertilizer uniformity from the largest to the smallest was:the rotation speed of the fertilizer discharge wheel,the forward speed,and the wind speed of the fan.According to the regression equation,the maximum value combination of the variation coefficient of fertilizer uniformity is as follows:the rotating speed of the conical rotary table is 15 r/min,the opening of the fertilizer discharge mouth is 5 mm,and the forward speed is 1.6 m/s.At this time,the variation coefficient of fertilizer uniformity is 20.12%.The difference between the test value and the theoretical value is 1.43%,which proves the accuracy of the results.The test results show that the performance of the fertilizer application device meets the national standard for fertilizer application machinery operation.This research designed a conical disc push plate lateral deep fertilization device.Through theoretical analysis,numerical simulation calculation,and experimental design methods,the structural dimensions,working process,and fertilization performance of the device were analyzed and studied,which to some extent solved the problems of poor fertilization stability and uniformity,and low fertilizer adjustment ability in the process of lateral deep fertilization in paddy fields,And the relationship between the optimal conveying speed of the air supply system and the fertilizer discharge rate was clarified.The research content and methods in this article can provide reference for the innovative design and application of side deep fertilization devices in paddy fields. |
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