Gang Zheng

To improve the uniformity and precision of soybean seeding, this study designed a high-speed airflow-assisted seeding system for the pneumatic drum-type high-speed precision seed-metering device. The system accelerates seed delivery through airflow and ensures precise seed placement using a seed press wheel. Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) coupling simulations were employed to analyze the seed motion trajectory, collision process, and velocity changes. Key design parameters of the airflow-assisted delivery system were optimized, including a tube diameter of 16 mm, a curved section radius of 80 mm, a seed delivery angle of 33.65°, and a press wheel diameter of 254 mm. The simulation results indicated that the relative position between the seed delivery tube and the seed drum significantly impacts seed trajectory and uniformity. Lowering the tube to align with the seed velocity direction minimized collisions and enhanced seed spacing consistency during high-speed operation. Increasing inlet air pressure improved seed distribution uniformity by accelerating seeds within the tube, reducing travel time and collisions; a 500 Pa pressure increase raised the maximum flow velocity by approximately 5 m/s. However, seed acceleration exhibited diminishing returns: pressure increase from 2.5 kPa to 3.5 kPa increased seed speed by 2.1 m/s, while a further increase to 4.5 kPa only added 1.1 m/s. The optimal inlet pressure for efficient energy transfer and seed acceleration was approximately 3.5 kPa. The press wheel played a crucial role by dispersing the impact force when seeds contact the soil, which achieved high capture rates above 94.0% across the seed drum rotary speed range of 11 to 19 rpm. This research provides theoretical and experimental support for the optimization of high-speed airflow-assisted seeding systems, offering significant practical value for large-scale agricultural production by enhancing seeding efficiency and quality.

In view of issues affecting manual on-demand sowing of spinach, such as high working intensity, low seeding efficiency, and high cost, a mechanized precision seeding device for spinach seeds is proposed, based on a spoon-wheel including a combined cell with two intersecting surfaces. The key structure was designed, and motion analysis was conducted employing SolidWorks software (2022). Additionally, the seeding process was simulated using EDEM simulation software (2022). The number of spoons, the radius of the spoons, and the speed of the seed wheel were chosen as the influencing factors, while the qualified index, reseeding index, and missing index were utilized as the evaluation indexes. A response surface method test based on the Box–Behnken design was carried out, and the test results were analyzed to obtain the optimal parameter combination for the seed-metering device. The field test results showed that when the rotation speed was 18 rpm, the radius of each seed spoon was 2.5 mm, and the number of seed spoons was 50, the average qualified index was 90.89%, the reseeding index was 8.22%, and the missed seeding index was 0.89%. The test results satisfy the technical production requirements for spinach seed sowing.