According to the agronomic requirements of cotton precision seeding, the researchers designed a split seeding system to achieve high-speed precision seeding on the membrane. The 3D models used in the simulation process were created using Solidworks. They used the built-in Flow Simulation plug-in in SolidWorks to simulate the flow field in the drum and to grasp the air velocity and pressure changes. The CFD-DEM (computational fluid dynamics and discrete element method) coupling method was used to simulate the positive pressure airflow to transport the seeds, so as to grasp the movement of the seeds in the seed tube. EDEM (engineering discrete element modeling) was used to simulate the seeding process of the hole seeder, to understand the movement speed and trajectory of the seeds inside the hole seeder, and to analyze the reasons for missed seeding and reseeding. A three-factor, five-stage quadratic rotation orthogonal combination test was designed using Design-expert 13.0 software. This test evaluates the performance of a split seeding system by establishing a response surface for the seed rate, using the hole seeder speed, negative pressure, and hole diameter as test factors. The optimal parameter combination is obtained by optimizing the regression equation, which is further verified by bench tests. Under the hole seeding speed of 47.98 r/min, the negative pressure of 1.96 kPa and the hole diameter of 3.5 mm, the precision seeding system achieved a single seed rate of 90.9% and a missed seed rate of 4.3%. The verification test results are consistent with the optimization results, which meet the agronomic requirements of high-speed precision film seeding. This research provides a better technical solution for the application development of a precision seeder.

In order to study the working mechanism and sowing effect of seed delivery pipes and their associated cavity seeders, the factors affecting the sowing test were first derived through pressure loss theory and force analysis of cotton seed particles in the gas-solid coupling field. Secondly, Ansys fluent was used to simulate the flow field of seed delivery pipe joints to study the effect of seed delivery pipe joints on the overall pressure loss and uniformity of air pressure distribution and to determine the optimal structure of seed delivery pipe joints. Then, the EDEM was simulated for the overall seed delivery pipe and its associated cavity seeders in the absence of positive pressure to analyze the transport pattern of each cotton seed. Finally, CFD-DEM gas-solid coupling simulation experiments were conducted on the center of two rows of seed delivery pipes and their connected cavity seeders to analyze the trajectory of cotton seeds under different rotational speeds of cavity seeders and different positive seed delivery pressures and to deeply analyze the causes of Multiple seeding and Miss-seeding. At the same time, the seeding performance was evaluated by coupling simulation values with single seeding rate and multiple seeding rate as seeding performance evaluation indexes and compared with bench test. The results show that in the coupling simulation, when the speed of the cavity seeders is 20~40 rev/min and the seed delivery tube is passed into 50~150 Pa positive pressure airflow, the single seeding rate is not less than 83.06%, and the missed seeding rate is not more than 9.23%. In the bench test, the single seeding rate was not less than 80.64%, and the missed seeding rate was not more than 9.86% under the same cavity seeders speed and positive pressure, and the results of the bench test and the simulation test were close and consistent, which verified the feasibility of the simulation.