The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devi...The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devices can only plant a single row at a time or need high airflow pressure,which complicates the seed-metering system and the seeder structure,deteriorate the working reliability and have high power consumption.To overcome above shortcomings,a novel prototype of pneumatic precision centralized seed-metering device with seed inside-filling,sowing six rows at a time,was developed.The main structure and working principle of the prototype were described and the technical parameters were given.Experiments were conducted to investigate the influences of positive pressure,negative pressure,and rotating speed on the seeding performance.The stability of each row and the consistency between all rows associated with the seeding precision were analyzed to evaluate the performance of the prototype.The results indicated that the prototype can meet the requirements of precision seeding and the seed keep intact without any obvious damage.The performance of the prototype was no significant difference when the positive pressure was fluctuated from 200 Pa to 1200 Pa.The best seeding precision parameters in one row of the prototype was 92.48%of the qualified seeding index(Iqs)and 2.55%of the miss-seeding index(Imiss),when the rotating speed was 16 r/min,the positive pressure was 200 Pa and the negative pressure was–1600 Pa.When the rotating speed was 16 r/min,the positive pressure was 200 Pa,and the negative pressure was–1400 Pa or–1600 Pa,the Iqs of six rows were above 86.5%,the stability coefficient of variation(CV)of each row were below 4.6%,and the consistency CV were below 0.9%.Further field experiment showed that the rapeseed sowed by the prototype had acceptable seeding precision.The CV of the numbers of rapeseed seedlings in the field of the total and each row were 6.17%and 6.32%respectively.The research conf展开更多
针对内充气吹式排种器对圆形种子适应性差、排种效果不佳的问题,对内充气吹式排种器进行优化设计,为增强种子充填容积和气流压附力在型孔底部开设不同结构的槽孔。基于离散单元法理论建立玉米籽粒粘结颗粒模型,运用EDEM-CFD耦合分析方法...针对内充气吹式排种器对圆形种子适应性差、排种效果不佳的问题,对内充气吹式排种器进行优化设计,为增强种子充填容积和气流压附力在型孔底部开设不同结构的槽孔。基于离散单元法理论建立玉米籽粒粘结颗粒模型,运用EDEM-CFD耦合分析方法,以型孔内种子在排种盘转动过程中所受的曳力值为指标,在入口风速为30 m/s、前进速度为8 km/h的工作条件下对3种不同型孔结构排种盘进行圆粒种子排种效果的耦合仿真,分析排种过程中圆粒种子所受曳力的变化情况及清种和压种性能。仿真结果表明:同一排种盘中,因大圆粒种子迎风面积大于小圆粒种子,所受曳力均大于小圆粒,迎风面积大的颗粒更易被清出型孔;径向内开方孔盘型孔内气流对颗粒的曳力及压附力均较大,且增大了型孔对种子在径向方向的充填容积,该盘对圆粒种子及混合种子的工作效果均较好。为验证仿真结果进行台架试验,当前进速度为8 km/h时进行3种排种盘工作压强的单因素试验,结果表明,径向内开方孔盘合格率随工作压强的增大而增大,当工作压强大于5.5 k Pa时,合格率超过95%,明显优于其他2个排种盘;对径向内开方孔盘进行前进速度为4~12 km/h、工作压强为4~8 k Pa的双因素试验,结果表明,合格率随着前进速度和工作压强的增大而增大,针对不同前进速度,当工作压强高于6 k Pa时,合格率接近96%,漏播率低于1%。展开更多
针对内充机械气力组合式排种器工作压强范围窄,排种器在工作压强范围外工作时,合格指数低的问题,该文基于气吹式排种器气流清种及气压式排种器种子压附原理,设计了一种内充气吹式排种器,对清种-压种组合式气嘴的倾角和安装位置进行设计...针对内充机械气力组合式排种器工作压强范围窄,排种器在工作压强范围外工作时,合格指数低的问题,该文基于气吹式排种器气流清种及气压式排种器种子压附原理,设计了一种内充气吹式排种器,对清种-压种组合式气嘴的倾角和安装位置进行设计计算。对清种气嘴的截面倾角进行流体仿真分析,并对不同类型的玉米种子在不同工作压强下进行了排种器台架试验。结果表明:不同类型种子的合格指数呈现出大扁种子>小扁种子>小圆种子>大圆种子的规律;工作压强为4.5和5.0 k Pa时,大扁种子和小扁种子的合格指数均达95%以上,该排种器适用于扁型种子的播种。展开更多
基金the National Natural Science Foundation of China(5140518)Modern Agro-industry Technology Research Systems(CARS-13)Scientific Research Outstanding Talent and Innovation Team Foundation of Ministry of Agriculture of China,and the Key Project of Hubei Province(2014070504020240).
文摘The pneumatic precision seed-metering devices used in combination with negative air pressure to suck seed and positive air flow to drop seed could overcome the problem of rapeseed precision planting.However,these devices can only plant a single row at a time or need high airflow pressure,which complicates the seed-metering system and the seeder structure,deteriorate the working reliability and have high power consumption.To overcome above shortcomings,a novel prototype of pneumatic precision centralized seed-metering device with seed inside-filling,sowing six rows at a time,was developed.The main structure and working principle of the prototype were described and the technical parameters were given.Experiments were conducted to investigate the influences of positive pressure,negative pressure,and rotating speed on the seeding performance.The stability of each row and the consistency between all rows associated with the seeding precision were analyzed to evaluate the performance of the prototype.The results indicated that the prototype can meet the requirements of precision seeding and the seed keep intact without any obvious damage.The performance of the prototype was no significant difference when the positive pressure was fluctuated from 200 Pa to 1200 Pa.The best seeding precision parameters in one row of the prototype was 92.48%of the qualified seeding index(Iqs)and 2.55%of the miss-seeding index(Imiss),when the rotating speed was 16 r/min,the positive pressure was 200 Pa and the negative pressure was–1600 Pa.When the rotating speed was 16 r/min,the positive pressure was 200 Pa,and the negative pressure was–1400 Pa or–1600 Pa,the Iqs of six rows were above 86.5%,the stability coefficient of variation(CV)of each row were below 4.6%,and the consistency CV were below 0.9%.Further field experiment showed that the rapeseed sowed by the prototype had acceptable seeding precision.The CV of the numbers of rapeseed seedlings in the field of the total and each row were 6.17%and 6.32%respectively.The research conf
文摘针对内充气吹式排种器对圆形种子适应性差、排种效果不佳的问题,对内充气吹式排种器进行优化设计,为增强种子充填容积和气流压附力在型孔底部开设不同结构的槽孔。基于离散单元法理论建立玉米籽粒粘结颗粒模型,运用EDEM-CFD耦合分析方法,以型孔内种子在排种盘转动过程中所受的曳力值为指标,在入口风速为30 m/s、前进速度为8 km/h的工作条件下对3种不同型孔结构排种盘进行圆粒种子排种效果的耦合仿真,分析排种过程中圆粒种子所受曳力的变化情况及清种和压种性能。仿真结果表明:同一排种盘中,因大圆粒种子迎风面积大于小圆粒种子,所受曳力均大于小圆粒,迎风面积大的颗粒更易被清出型孔;径向内开方孔盘型孔内气流对颗粒的曳力及压附力均较大,且增大了型孔对种子在径向方向的充填容积,该盘对圆粒种子及混合种子的工作效果均较好。为验证仿真结果进行台架试验,当前进速度为8 km/h时进行3种排种盘工作压强的单因素试验,结果表明,径向内开方孔盘合格率随工作压强的增大而增大,当工作压强大于5.5 k Pa时,合格率超过95%,明显优于其他2个排种盘;对径向内开方孔盘进行前进速度为4~12 km/h、工作压强为4~8 k Pa的双因素试验,结果表明,合格率随着前进速度和工作压强的增大而增大,针对不同前进速度,当工作压强高于6 k Pa时,合格率接近96%,漏播率低于1%。
文摘针对内充机械气力组合式排种器工作压强范围窄,排种器在工作压强范围外工作时,合格指数低的问题,该文基于气吹式排种器气流清种及气压式排种器种子压附原理,设计了一种内充气吹式排种器,对清种-压种组合式气嘴的倾角和安装位置进行设计计算。对清种气嘴的截面倾角进行流体仿真分析,并对不同类型的玉米种子在不同工作压强下进行了排种器台架试验。结果表明:不同类型种子的合格指数呈现出大扁种子>小扁种子>小圆种子>大圆种子的规律;工作压强为4.5和5.0 k Pa时,大扁种子和小扁种子的合格指数均达95%以上,该排种器适用于扁型种子的播种。
