DEM-CFD coupling simulation and optimisation of rice seed particles seeding a hill in double cavity pneumatic seed metering device

The key factor in improving the field distribution and yield of rice is precise seeding of rice seed particles in a hill. In this study, a positive pressure precision seed throwing device was designed to enhance the performance of rice seeding on a hill and address the issue of uneven distribution of rice seed particles in the field using the double cavity pneumatic seed metering device. CFD-DEM (Computational Fluid Dynamics - Discrete Element Method） coupled simulation technology was employed to analyse the seeding in a hill and the motion of rice seed particles. The movement details and state of rice seed particles in the airflow were examined, and the effect of precision transportation under different parameters of the positive pressure precision seed throwing device was investigated. The results indicate that an increase in inlet air velocity leads to greater lateral displacement of rice particles under the same inlet angle. A good performance of seeding on a hill was observed when the inlet air velocity was 3 m/s, the inlet angle was 60°, and the speed of the seed sucking plate was 20 r/min. The simulation results identified the optimal hill diameter as 27.5 mm. Subsequent actual tests conducted under the same conditions yielded an optimal hill diameter of 31.2 mm. The results of the actual test and simulation test were basically consistent. This study successfully enhanced the performance of rice seeding on a hill, meeting the requirements for field seeding on a hill.