摘要
穴施肥装置气力投肥过程要求气流将肥团从肥腔中全部清出并尽量减小肥料在土壤中的分布长度,为明确不同投肥路径下投肥机构内流场分布及其对肥团运动的影响,该文运用CFD-DEM耦合方法,根据出肥管与肥盘接触面的不同,对比分析了不同入口风速(4、6和8 m/s)下侧投肥和底投肥2种投肥路径下机构内流场和颗粒的运动特性,结果表明:当肥腔与进气端面接触面积较小时,肥腔内气流流速和颗粒扰动过大,出现颗粒"倒流"现象;随接触面积增大,肥腔内气流流速和颗粒扰动逐渐减小,投肥趋于稳定;当入口风速较小时,2种投肥路径投肥性能均相对较差;随入口风速增大,两者清肥率和肥料成团性能均明显提高,当入口风速达到8m/s时,底投肥方式清肥性能优于侧投肥方式,而肥料成穴性能却低于后者。室内台架试验表明其投肥性能指标的变化规律与仿真试验相吻合,且入口风速达到8m/s时,侧投肥方式的清肥率和肥料分布长度分别为85.5%和9.9 cm,底投肥方式分别为87.1%和11.4 cm。仿真和台架试验结果为后续投肥路径的设计和优化提供了理论依据。
The pneumatic hole-fertilization device can deliver a pre-calculated amount of fertilizer to pre-designed locations in soil and is hence effective in improving fertilizer use efficiency.The operation of the pneumatic hole-fertilization device consists of three steps:taking fertilizer,transporting it and injecting it to soil.To ensure accuracy in taking fertilizer,it needs to completely remove the fertilizer from the chamber in the device and curtail spatial distribution of the fertilizer in soil during the injecting process.The structure of the gas channel in the injecting component controls the quality of fertilizer transporting,while the fertilizer movement in the chamber remains elusive.There is a paucity of study about the impact of fertilizer-moving route on performance of the device.Depending on how the disposing outlet pipe is connected to the fertilizer-plate,the fertilizer injection can be divided into lateral injection and bottom injection.In this paper,we simulated the impact of the two injections on fertilizer movement using the discrete element method software-EDEM,and then coupled it with CFD to simulate gas flow and fertilizer movement under different inlet velocities.The results showed occurrence of backflow of the fertilizer as airflow velocity increased due to the disturbance caused to the fertilizer in the chamber when the connected area between the chamber and the inlet pipe was small.Increasing the connected area can attenuate gas flow velocity and reduce fertilizer disturbance,thereby stabilizing fertilizer movement.When the inlet velocity was 4 m/s,both injections worked poorly.Increasing the inlet velocity could improve fertilizer removal rate and the accumulation performance.When the inlet velocity was 8 m/s,the accumulation performance of fertilizer under lateral injection was superior to under bottom injection,while the bottom injection had the edge in fertilizer-clearing rate.We also conducted a bench experiment under different inlet velocities to compare the two injections by capturin
作者
刘正道
王庆杰
李洪文
何进
卢彩云
于畅畅
Liu Zhengdao;Wang Qingjie;Li Hongwen;He Jin;Lu Caiyun;Yu Changchang(College of Engineering,China Agricultural University,Beijing 100083,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2019年第21期18-25,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家重点研发计划项目(2016YFD0200600)
关键词
农业机械
试验
穴施肥
投肥路径
CFD-DEM
成团性能
清肥率
agricultural machinery
experiments
hole-fertilization
fertilizer injecting method
CFD-DEM
performance of assembly
fertilizer-clearing rate
