Abstract: The efficiency of manually sowing Polygonatum sibiricum seeds is low and the cost is high, besides the existing Polygonatum seeders mostly use mechanical seeders, resulting in obvious seed jamming and a high rate of seed damage. In response to the above issues, an air-suction precision seeding apparatus has been designed with strong universality for different sizes of Polygonatum seeds and meets the requirements of dense planting agronomy. Firstly, the planting technology and physical characteristics of Polygonatum seeds were analyzed, and it was found that Polygonatum seeds were small and medium-sized seeds with 1 000-grain weight of 35.60 g, sphericity of 89.95% and equivalent particle size of 3.57 mm. Secondly, the overall structure and working principle of the seeding apparatus were explained, and the working process of the seederwas divided into three areas: seed filling area, seed carrying area, and seed dropping area. Thirdly, according to the agronomic requirements of Polygonatum sibiricum seeds, the shape structure and size parameters of the main components of the seed metering device were designed. Finally, the Discrete Element Method (DEM) was used to analyze the seed filling process of Polygonatum sibiricum, and solved the motion law of the seed without negative pressure, the Computational Fluid Dynamics (CFD) method was used to analyze the internal flow field of the metering device, and solved the pressure and flow rate of flow field at the negative pressure chamber, the EDEM-FLUENT coupling was used to analyze the seeding performance of the seeding apparatus, solved the seed movement law under negative pressure, and analyzed the filling performance, carrying performance and throwing performance of the seed metering device. The simulation results indicate that when the speed of seed discharging disk is 30 r/min, the negative pressure of pneumatic tube is 3.5 kPa, the qualified rate is 90.5%, the reseeding rate is 6%, the leakage rate is 3.5%, the performance of seed discharging is good.

Key words: Polygonatum, airsuction metering device, discrete element method, CFD, EDEM-FLUENT coupling

摘要： 人工播种黄精种子的效率低、成本高，现有黄精播种机多采用机械式排种器，存在卡种现象明显、种子损伤率高等问题。针对这些问题，设计一款对不同尺寸黄精种子通用性强，且满足其密植农艺要求的气吸式精密排种器。对黄精种子的种植技术及物理特性进行分析，得到黄精种子是千粒重为35.60 g、球形度为89.95%、等效粒径为3.57 mm的中小粒径种子；对排种器整体结构及工作原理进行阐述，并将排种器工作过程分为3个区域：充种区、携种区、投种区；根据黄精种子农艺要求，对排种器主要部件进行形状结构和尺寸参数设计。利用离散元法（DEM）分析黄精种子充种过程，求解无负压状态下种子运动规律；利用计算流体力学法（CFD）分析排种器内部流场，求解负压室流场压力及流速情况；利用EDEM-FLUENT耦合分析排种器排种性能，求解负压状态下种子运动规律并分析排种器充种性能、携种性能以及投种性能。仿真结果表明：当排种盘转速为30 r/min、气压管负压为3.5 kPa时，设计的排种器排种合格率为90.5%，重播率为6%，漏播率为3.5%，排种性能良好。

关键词: 黄精, 气吸式排种器, 离散元法, 流体力学法, EDEM-FLUENT耦合