Optimizing seed filling performance of the double-filling air suction maize and soybean seed metering device based on DEM-CFD coupling method

• Increased seeding speed reduces drag force, compromising seedling establishment. • With the increase of hole diameter, filling index first rises and then falls. • With the increase of negative pressure, filling index first rises and then falls. • Increasing the hole number will cause seed filling index to first rise and then fall. To attain single particle accurate adsorption and improve the efficacy of seed leakage control, the double-filling air suction maize and soybean seed metering device was carried out, ensuring improved filling time and drag force while maintaining optimal seed filling performance. The filling performance was investigated by analyzing the impact of seeding speed, the number and diameter of single row holes and air chamber negative pressure on a precision air suction seed-metering device with double-filling capability. The relationship between seed movement and drag force is an important research method for studying the adsorption performance of seed filling. The gas–solid interaction dynamics within the air suction seed-metering device were investigated through a coupled DEM-CFD simulation framework, enabling comprehensive analysis of multiphase flow behavior and particle–fluid interactions. At the micro scale, reducing seeding speed and increasing air chamber negative pressure will result in higher and more consistent negative pressure and drag force at the hole. Single-factor experiments and quadratic rotational orthogonal composite designs were conducted, with the maximum single seed filling index serving as the primary optimization criterion. The double-filling air suction maize and soybean seed metering device’s ideal parameter combination was 4.5 mm hole diameter, 26 holes in a single row, 5 kPa air chamber negative pressure, and 8.3 km/h seeding speed. Predicted values of seed filling index for maize and soybean were 96.27 % and 96.17 %, respectively. Validation tests confirmed that optimized parameters at operational speeds of 8–12 km/h satisfied agronomic standards for high-speed precision seeding of maize and soybeans, demonstrating a qualification index exceeding 91.66 % and a coefficient of variation below 6.26 %.