气力滚筒式排种器种子吸附边界模型及验证  

Mathematical modeling and validation of seeder's suction-boundary on pneumatic-roller type metering

作　　者：张静[1] 李志伟[1] 刘皞春 吴钢[1] Zhang Jing Li Zhiwei Liu Haochun Wu Gang(College of Engineering, South China Agricultural University, Guangzhou 510642, China)

机构地区：[1]华南农业大学工程学院,广州510642

出　　处：《农业工程学报》2016年第23期12-20,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家"863"计划资助项目(2013AA102406-03)

摘　　要：为了探索气力滚筒式播种机对不同规格小粒蔬菜种子吸附性能的影响,该文对种子在吸种孔外部气流场中处于临界运动时与吸种孔的位置关系进行了理论分析。通过分析吸种孔外部气流场的气体的流动状态以及种子在气流场中的绕流阻力与其到吸种孔距离的关系,并对种子在气流场中运动临界状态进行受力分析,从而推导出种子吸附边界的数学模型。分析吸附边界大小对种子吸附性能的影响,以菜心种子、芥兰种子、辣椒种子为试验对象,排种器真空度在1 k Pa^12 k Pa变化,吸种孔半径为0.25 mm,导种板为无振动和振幅为0.4 mm。试验结果与模型分析结果一致:种子吸附的前提条件是种子持续不断的进入吸附边界内,种子的吸附性能与种子边界的大小和种子形状和大小有关;对于小粒蔬菜种子,扁平种子的单粒率低于球形种子,球形种子的直径越小,越难获得高的单粒率。对于小粒扁平种子和直径较小的小粒球形种子,合理的供种方法和增大排种器真空度使吸种孔不空种,再清除吸种孔上的多余种子,是实现排种器精密播种的一种途径。研究结果为气力滚筒式播种机的精密播种研究提供参考。Aiming to explore the influence of pneumatic roller type seeder on the absorbability of small seeds with varied sizes, the paper performs a theoretic analysis on the relation between the seed that is in critical motion in the airflow field outside the suction pore and the corresponding position of the suction pore. The state of gas-flow in the airflow field outside the suction pore is analyzed as well as the connection between the seed＇s flow resistance in the airflow field and the seed＇s distance to the center of the airflow field, and furthermore, a force analysis is conducted on the seeds in critical motion in the airflow field. Subsequently, a mathematical model of seeds＇ suction-boundary is established. Simple comparison approach is adopted. The experiment conditions are that the diameter of the seed is 2 mm, the vacuum pressure of seed metering device is 4 kP a, the diameter of suction pore is 0.25 mm, and the frictional coefficient of seeds is 0.3; then the parameters above are changed respectively： the diameter of the seed is 1.4 mm, the vacuum pressure is 4 kP a, the diameter of suction pore is 0.4 mm, and the frictional coefficient is 0.01; thus the values of suction-boundary are able to be achieved accordingly. According to a set of suction-boundary values, the suction-boundary as well as its motion region will constantly will remain steady as the diameter of seeds decreases. When the vacuum pressure and the diameter of suction pore increase, the suction-boundary along with its motion region will expand accordingly. When the frictional coefficient is reduced, the suction-boundary along with its motion region will expand as well. In the research regarding the influence exerted by the size of seeds＇ suction-boundary over the absorbability of seed metering device, the seeds of flowering Chinese cabbage and broccoli along with hot pepper are used as experimental materials with the vacuum pressure of seed metering device ranging from 1 to 12 kP a. Other parameters of the experiment are defined as

关 键 词：模型 气流场 种子 吸附边界 滚筒式排种器 吸种孔 

分 类 号：S223.2[农业科学—农业机械化工程]