Influence of the divider head functioning conditions and geometry on the seed's distribution accuracy of the air-seeder

EA GEAPSI AGROSUPInternational audienceAs the working width of sowing implements increases, the use of conventional mechanical seed drills, with hoppers above all the implement working width, has reachedits limits. Any further increase of the working width (more than 4-6 m) or the coupling of conventional additional apparatus is expensive, complex and time-consuming. Air-seeding appears thus as the best solution to solve this problem. One storage hopper is able to supply the working width of 24 m or more. However, it should be noticed that to ensure uniform crop growing, a machine needs an accurate, technical solution to ensure seeding material to be distributed across the full implement working width. Indeed, low transversal distribution accuracy is one of the most important shortcomings of modem air-seeders. Even if air-seeding has been used for more than 50 years, few developments have been carried out on divider headers responsible for distribution accuracy.This paper deals with a study on the influence of divider head geometry and functioning conditions on the seed's distribution accuracy. The first part concerns the study of the influence of the air velocity and the material flow rate on the distribution accuracy. A second study deals with the influence of the outlet closing, of different outlet pipes lengths, of distribution head tightness, of the angle position of distribution heads. Finally the influence of the structural elements such as the pipe elbow, the tower configurations, the tower height and the cone shape deflectors' implementation on the divider lid is proposed. Moreover, observation of the seed's behaviour is undertaken using a high-speed camera system. These experimental results allowed for proposals of hypothesis about the parameters influencing the final result. This paper also proposes theoretical and mathematical explanations of the observed effects, necessary for future divider heads design