DESIGN OF A CENTRIFUGAL WORKING UNIT OF A MINERAL FERTILIZER SPREADER

In variable-rate application of solid mineral fertilizers (SMF), working units of centrifugal fertilizer distributors can regulate precisely the application rate and evenly distribute pellets over the fi eld. To determine the most rational parameters and modes of a solid fertilizer distributor, infl uencing the fl ight path of pellets and the uniformity of their distribution over the fi eld, the authors carried out theoretical and experimental research of a centrifugal disc of a solid fertilizer distributor equipped with a rotary acceleration chamber and a set of exchangeable U-shaped blades. The authors describe the infl uence of the blade length on the trajectory and the fl ight distance of the fertilizer pellets as well as the infl uence of the rotation of the dispersal chamber outlet window on the fertilizer distribution pattern. The experiment on determining aerodynamic properties of the nitroammonium phosphate pellets (60:60:60) was carried out using the developed laboratory bench of the solid fertilizer distributor. The experiment allowed determining the physical parameters of pellets infl uencing the range and trajectory of their fl ight - the winglet ratio and the critical speed. It was found that the rotation displacement of the dispersal chamber outlet window of the spreading disc leads to the displacement of the intensive coverage zone in the direction of the window rotation. This makes it possible to regulate the intensity and has a direct impact on the distribution zone of solid mineral fertilizers. The paper justifi es the most rational design of the spreading disc. The research proved that the greatest uniformity of solid mineral fertilizer spreading is observed when using a disk with eight paired coaxially located blades with a length of 300, 250, 200, and 100 mm.