In order to analyze seed movement characteristics and improve seeding quality of air-assisted centralized metering device for rapeseed,the effects of the model-hole structure on seed feeding performance were investiga...In order to analyze seed movement characteristics and improve seeding quality of air-assisted centralized metering device for rapeseed,the effects of the model-hole structure on seed feeding performance were investigated using EDEM simulation.Furthermore,the CFD-DEM coupling approach was applied to determine movement trajectories and airflow fields.The impacts of rapeseed varieties and rotational speed on seeding performance were investigated by bench tests.The results showed that the seed feeding quantity increased with the increase of model-hole’s length,depth and section size.Under the model-hole’s depth of 3.0 mm,the type II model-hole and model-hole’s length of 10 mm,both the variation coefficient of seed feeding quantity and hill diameter were lower which meet the seeding quantity requirement of 2 seeds in each hill.It was revealed that the seed population migrated in a large airflow velocity area and the distribution was uniform.The bench tests indicated that rapeseed varieties and rotational speed had a significant effect on the seed feeding quantity in each hill at rotational speed of 10-40 r/min.The variation coefficient of seed feeding quantity in each hill was less than 17.0%for each treatment.The hill diameter,which did not exceed 3.5 cm,tended to reduce with increasing rotational speed.The variation coefficient of seeding quantity in each row and seeding uniformity was less than 6.5%and 32.0%,respectively.Field experiments demonstrated that the seedling was 9-13 plants per meter each row for three rapeseed varieties.The variation coefficient of plants was less than 25.0%for six rows and their yields reached 2761 kg/hm2,which realized the mechanized planting requirements.The results can optimize structure of an air-assisted centralized metering system and improve seeding performance.展开更多
为直观准确观察排种器的工作特性以及种子在其容腔内部的运动状态,利用高速摄像技术拍摄立式浅盆型排种器在不同转速下的工作过程,同时结合离散元仿真软件EDEM（engineering discrete element method）进行仿真,利用其后处理模块中的影...为直观准确观察排种器的工作特性以及种子在其容腔内部的运动状态,利用高速摄像技术拍摄立式浅盆型排种器在不同转速下的工作过程,同时结合离散元仿真软件EDEM（engineering discrete element method）进行仿真,利用其后处理模块中的影像技术标记种子并对工作区间进行分析。采用高速摄影技术和离散元仿真分析软件EDEM分析得出：为了保证清种的可靠性,种盘的折边倾角应在67°-90°之间;同时,为了防止清种过程中带种导致的伤种现象的发生,种层高度应保证种面与护种板之间保留3-4倍种子直径的距离;投种过程中,为了保证排种的均匀性、减小株距变异,在保证型孔的光洁度的同时,投种口的尺寸应选取16 mm×30 mm。该研究为完善立式浅盆型排种器的设计、补充修正相关结构参数提供了参考。展开更多
针对机械式精密排种器在工作速度提高时,充种指数下降较快,从而导致作业质量严重下降的问题,在理论分析的基础上,创新设计了一种对置斜盘大豆排种器。该型排种器充分利用壳体的结构空间布置核心部件,从而提高排种频率、改变充填模式、...针对机械式精密排种器在工作速度提高时,充种指数下降较快,从而导致作业质量严重下降的问题,在理论分析的基础上,创新设计了一种对置斜盘大豆排种器。该型排种器充分利用壳体的结构空间布置核心部件,从而提高排种频率、改变充填模式、增加充填力种类,以适应高速作业需求。根据该排种器的工作原理建立数学模型,分析种盘在不同倾斜角度时充填力的变化规律,优化角度为20°;运用工程离散元方法（engineering discrete element method,EDEM）将对置斜盘排种器与一种具有一定高速作业能力的双腔立式复合圆盘排种器进行虚拟仿真及样机试验对比,进一步验证了该种结构形式的优越性,试验结果表明在8~12 km/h高速区段平均合格指数较对照排种器提高约3.6%。研究为高速机械式精密排种器的设计与开发提供了机械形式方面的创新思路以及分析方法方面的借鉴与指导。展开更多
基金supported by the National Natural Science Foundation of China(Grant No.31901413)the National Key Project of Research and Development Program,Ministry of Science and Technology of the People’s Republic of China(Grant No.2018YFD0301204).
文摘In order to analyze seed movement characteristics and improve seeding quality of air-assisted centralized metering device for rapeseed,the effects of the model-hole structure on seed feeding performance were investigated using EDEM simulation.Furthermore,the CFD-DEM coupling approach was applied to determine movement trajectories and airflow fields.The impacts of rapeseed varieties and rotational speed on seeding performance were investigated by bench tests.The results showed that the seed feeding quantity increased with the increase of model-hole’s length,depth and section size.Under the model-hole’s depth of 3.0 mm,the type II model-hole and model-hole’s length of 10 mm,both the variation coefficient of seed feeding quantity and hill diameter were lower which meet the seeding quantity requirement of 2 seeds in each hill.It was revealed that the seed population migrated in a large airflow velocity area and the distribution was uniform.The bench tests indicated that rapeseed varieties and rotational speed had a significant effect on the seed feeding quantity in each hill at rotational speed of 10-40 r/min.The variation coefficient of seed feeding quantity in each hill was less than 17.0%for each treatment.The hill diameter,which did not exceed 3.5 cm,tended to reduce with increasing rotational speed.The variation coefficient of seeding quantity in each row and seeding uniformity was less than 6.5%and 32.0%,respectively.Field experiments demonstrated that the seedling was 9-13 plants per meter each row for three rapeseed varieties.The variation coefficient of plants was less than 25.0%for six rows and their yields reached 2761 kg/hm2,which realized the mechanized planting requirements.The results can optimize structure of an air-assisted centralized metering system and improve seeding performance.
基金Specialized Research Fund for the Doctoral Program of Higher Education jointly funded subject(No.:305110002)Heilongjiang Provincial Science and Technology projects(GZ11B109)
文摘为揭示水稻钵盘精量播种装置投种过程,以水稻钵盘精量播种装置为研究对象,借助高速摄像技术对稻种投种过程和稻种的运动方式进行了观察,通过分析可知,稻种在运动中伴有自转、偏转等现象,运动轨迹符合二次曲线,垂直速度随时间增加而非线性增加,经拟合符合 Yield Density 模型;稻种水平位移与垂直位移有关。综合考虑投种率和投种效率,确定了垂直位移最大值为 31 mm。该结果为提高播种装置的投种率提供理论依据。
文摘针对机械式精密排种器在工作速度提高时,充种指数下降较快,从而导致作业质量严重下降的问题,在理论分析的基础上,创新设计了一种对置斜盘大豆排种器。该型排种器充分利用壳体的结构空间布置核心部件,从而提高排种频率、改变充填模式、增加充填力种类,以适应高速作业需求。根据该排种器的工作原理建立数学模型,分析种盘在不同倾斜角度时充填力的变化规律,优化角度为20°;运用工程离散元方法（engineering discrete element method,EDEM）将对置斜盘排种器与一种具有一定高速作业能力的双腔立式复合圆盘排种器进行虚拟仿真及样机试验对比,进一步验证了该种结构形式的优越性,试验结果表明在8~12 km/h高速区段平均合格指数较对照排种器提高约3.6%。研究为高速机械式精密排种器的设计与开发提供了机械形式方面的创新思路以及分析方法方面的借鉴与指导。
