Simulation and measurement of the suction force on ellipsoidal seeds in an air-suction seed-metering device

There is a lack of knowledge of the behaviour of non-spherical seeds in air-suction seedmetering device and this contributes to current designs having low qualified rates for nonspherical seed sowing. This study investigated the factors that may influence the suction force on ellipsoidal seeds based on computational fluid dynamic (CFD) simulations and measurements using a custom-made suction force measurement device. Single-factor measurements demonstrated that negative pressure, distance from the seed centre to the suction hole, seed attack angle, seed equivalent diameter, and suction hole diameter had a significant effect on suction force. CFD simulations revealed that the pressure gradient across the seed surface dominated the suction force. Since the suction hole shape determined the distribution of the pressure gradient around the hole, this explained the significant differences in suction force. Specifically, cylindrical holes offered a wider suction area than countersunk holes, whilst the latter exhibited better seed-carrying stability. Seed posture affected suction force by changing the location of the seed in the pressure gradient field. Seeds in a lying posture were more easily filled and carried due to their greater suction force. A preliminary ellipsoidal seed suction force model was constructed by regression analysis of the orthogonal experimental data. Validation experiments using soybean and red bean seeds revealed that the constructed model effectively predicted the suction force of ellipsoidal seeds with high prediction accuracy. (c) 2023 IAgrE. Published by Elsevier Ltd. All rights reserved.