Abstract
To enhance the seeding accuracy of multi-seed-per-hole operations for small-seed crops, a combined experimental-CFD optimization method for an air-suction seed metering plate was developed. Single-factor tests established that the suitable suction-hole diameter was 0.4-0.6 times the equivalent seed diameter, and threshold-based negative-pressure tests were used to define the acceptable suction-hole negative-pressure range for millet, broomcorn millet, and rapeseed. CFD pressure-tracing analysis was then performed to quantify the mapping between suction-hole pressure and air-chamber inlet negative pressure. On this basis, a three-factor, three-level optimization test was conducted using inlet negative pressure, suction-hole diameter, and suction-hole thickness as variables, with the qualification rate of suction-hole pressure as the response. The optimized parameter combinations were 2.51 kPa, 0.88 mm, and 0.31 mm for millet; 2.97 kPa, 1.12 mm, and 0.35 mm for broomcorn millet; and 2.35 kPa, 0.93 mm, and 0.32 mm for rapeseed. Bench validation showed seed-filling rates of 93%, 97%, and 96%, respectively. The results demonstrate that the proposed method can effectively reduce empirical trial workload and provide a practical basis for the design of pneumatic precision seed metering plates for small-seed crops.