基于DEM-CFD耦合的气力式播种机分配器数值模拟与试验

为研究不同类型气力式播种机分配器对披碱草排种性能的影响,通过离散元法与计算流体动力学耦合仿真的方法进行分配器颗粒运动数值分析。在气固耦合模型中,使用EDEM软件模拟固体相披碱草颗粒,Fluent软件描述气体相。通过研究上凸盖、平盖和圆锥盖型分配器对气流压力、颗粒碰撞和颗粒运动特性的影响,明确圆锥盖型分配器能耗最高,颗粒碰撞次数最多;平盖型分配器最节约能量,碰撞次数最少,对牧草种子破坏最小。研究发现,颗粒在分配器顶部发生碰撞后,反射角越大,径向速度越大,颗粒碰撞次数越多。对装有平盖型分配器的播种机进行披碱草排种性能试验,试验指标各行排量一致性变异系数为4.83%,总排量稳定性变异系数为3.97%,披碱草种子破碎率为1.36%,均达到国家标准的要求。仿真和试验结果为后续气力式播种机分配器的设计和优化提供设计思路。

Numerical simulation and experiment of distribution head of air-blown seed drill based on DEM-CFD coupling

To study the influence of distribution heads of different types of air-blown seed drills on the seed metering performance of Elymus,the particle movement of distribution heads was numerically analyzed by Discrete Element Method(DEM)and Computational Fluid Dynamics(CFD)coupling simulation method.In the gas-solid coupling model,EDEM software was used to simulate the solid phase of Elymus particles,and Fluent software was used to describe the gas phase.Through studying the effects of upper convex cover,flat cover,and conical cover distribution heads on airflow pressure,particle collision,and particle movement characteristics,it was clear that conical cover had the highest energy consumption and the most particle collision times.Flat cover was the most energy-saving,had the least collision times,and had the minimum damage done to forage seeds.It was found that the larger the reflection angle,the greater the radial velocity and the more times of particle collisions after particles collided with the top of the distribution head.As the static pressure at the distribution head s inlet increased,the fan s energy increased accordingly.The seed metering performance of Elymus was tested on the planter equipped with a flat cover distribution head.The apiece row consistency variability coefficient of seeding quantity was 4.83%,the stability variability coefficient of the full seeding quantity was 3.97%,and the breaking ratio of the Elymus seeds was 1.36%,all of which met the requirements of national standards.The simulation and test results provided an idea for the future design and optimization of the distribution head of the air-blown seed drill.