稻米清选的数值模拟研究与试验

采用"多球丛聚法"对稻米、稻秆、碎稻秆三种颗粒进行建模,并利用DEM-CFD耦合方法对不同气流速度、不同气流倾角时稻米清选的过程进行数值模拟,对不同参数下稻米的含杂率和夹带损失率进行对比,分析改变气流速度与倾角对气流速度分布及稻米平均含杂率、夹带损失率的影响规律,设计稻米清选的试验装置并进行了试验。结果表明:当气流速度设置为5 m/s时,稻米的平均含杂率为10.575%,夹带损失率为0.066%,将气流速度增大至9 m/s时,稻米的平均含杂率降低至0.307%,而夹带损失率上升至1.275%;气流速度为9 m/s,气流倾角倾斜10°条件下,稻米的平均含杂率相比气流倾角为0°条件下降低0.025%,而夹带损失率上升0.308%。通过对比发现试验结果模拟与仿真结果基本一致,表明利用DEM-CFD耦合方法对稻米清选过程的模拟是可靠的。

Numerical simulation and experiment of rice cleaning

The three kinds of particles of rice, rice straw and broken rice straw were modeled by "overlapping multisphere clump method", and the DEM-CFD coupling method was used to simulate the process of rice cleaning in different airflow velocitys and different airflow inclined angles. Comparing the airflow velocity contour diagram under different parameters and the velocity of three kinds of particles in the airflow field, the influence law of changing airflow velocity and airflow inclined angle on cleaning efficiency was obtained. The experiment device for rice cleaning was designed and experimented. The results show that when the airflow inclination is constant, the airflow velocity is higher, the average impurity rate is lower, and the entrainment loss rate is higher. When the airflow velocity is constant, the airflow inclined angle is larger, the average impurity rate is lower, and the entrainment loss rate is higher. The simulation results of the experiment results are consistent. The simulation based on the DEM-CFD coupling method is reliable for the rice cleaning process.