The stable and uniformly distributed airflow field can effectively improve the seed suction effect and seed-carrying stability of the pneumatic seeder. With this end in view, this paper was optimized the airflow basin structure of vacuum-vibration tray precision seeder based on the computational fluid dynamics (CFD) simulation technology. The results show that the airflow field is relatively stable and well-distributed when the chamber height is 50 mm and the outlet tube diameter is 65 mm. In addition, the thickness of the base plate with suction holes should be less than 5 mm, and the needle suction nozzle guide should be greater than 15 mm according to the numerical analysis results. On the basis of the above study, the seeding characteristics of the needle type suction nozzle and the plate type suction nozzle were further explored to determine the type of nozzle more suitable for rectangular sucker. Through various experimental designs, the significant influencing factors of the two suction nozzles and their appropriate working ranges as well as the optimal combination of working parameters were determined in turn. The needle suction nozzle requires lower suction height and less grains dispersion according to the experimental results, while the plate suction nozzle is just the opposite, it allows a certain suction height to be maintained with the seeds, and requires high dispersion of grain. In general, the plate suction nozzle can obtain better seeding performance, is a more favorable nozzle for the vacuum-vibration tray precision seeder.

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Vacuum-vibration precision seeding technology is a crucial technology that affects the industrialization process of super rice plug seedlings. To solve the problems that the vibrating supply seed tray structure in a vacuum-vibration precision seeder caused the vibration of the whole machine and the decline of the seeding eligible rate under high frequency and large amplitude vibration, it is important to design a new supply seed tray structure. This research proposed a method to make the seeds "boiling" under the combined effect of air blowing and vibration, and designed the air-blowing and vibrating supply seed tray structure. FLUENT was used to analyze fluid motion inside the supply seed tray and optimize the structure parameters of the supply seed tray. The maximum airflow velocity was determined when the inlet air pressure was 22 kPa, the number of air inlets was 2, and the diameter of the holes at the bottom of the supply seed tray was 2 mm. Comparative experiments were carried out to prove the air-blowing and vibrating supply seed tray structure could reduce the vibration frequency by 1.5 Hz and decrease the amplitude by 0.25 mm. The mathematical regression models between the inlet air pressure, vibration frequency, amplitude, and seeding performance indexes were established by orthogonal experiments. Through the optimization operation and bench tests, it was determined that when the inlet air pressure was 19.49 kPa, the vibration frequency was 9.00 Hz, and the amplitude was 2.65 mm, the eligible rate, replay rate, and hole rate could reach 93.56%, 3.35%, and 3.09%. The experimental results were generally consistent with the predicted values. The research confirmed that the air-blowing and vibrating supply seed tray could improve the eligible rate while reducing the vibration frequency and amplitude of the vacuum-vibration tray precision seeder. It also provided a necessary basis for precision seeding technology.