DESIGN AND EXPERIMENT OF AN AIR-ASSISTED, GUIDED-GROOVE MAIZE SEED-GUIDING DEVICE BASED ON THE BRACHISTOCHRONE CURVE

To address the issue that existing seed-guiding devices struggle to meet the high-speed operational requirements of delta-row planters for dense maize planting, a seed-guiding device with air assistance and a guided groove was designed based on the principle of the brachistochrone. The overall structure and working principle of the device are described, and the curved segment of the seed guide tube was optimized using the brachistochrone principle while accounting for frictional effects. Computational fluid dynamics (CFD) simulations were conducted to analyse the flow field characteristics of the seed guide tube at inlet airflow velocities of 63.48, 60.64, 57.73, 54.69, 51.50, and 48.15 m/s. A multi-factor test was performed using chamber pressure and operating speed as test factors, with the qualified index of grain spacing and the coefficient of variation as evaluation metrics. Comparative tests were conducted using a traditional guided-groove seed guide tube and a brachistochrone-based seed guide tube without a guided groove. Results showed that the optimal parameter combination for the newly designed device was a chamber pressure of 3.124 kPa and an operating speed of 12.0 km/h. Under these conditions in the bench test, the qualified index reached 97.04%, and the coefficient of variation was 6.18%, outperforming the other two types of seed-guiding devices. These findings demonstrate that the seed-guiding device based on the brachistochrone principle can significantly improve the seeding quality of delta-row planters for dense maize planting under high-speed operation.