Development of a DEM-Optimized Inclined Screw Fertilizer Distributor for Improving Discharge Stability and Metering Accuracy
Discharge uniformity and metering accuracy are essential for precision fertilization. An inclined screw fertilizer metering device with a spherical buffering outlet was designed and optimized using the discrete element method (DEM) and bench experiments. A particle-flow model was established using EDEM (DEM simulation software) to evaluate the effects of conveying inclination angle and outlet accumulation length on discharge performance using the coefficient of variation (CV), standard deviation, amplitude, and pulsation degree. Single-factor tests indicated that an inclination angle of 12° and an accumulation length of 32 mm produced favorable discharge performance. Two-factor optimization identified 13.5° and 40 mm as the optimal combination, yielding the lowest CV (2.36%) and standard deviation (51.88). Bench experiments further verified the performance of the optimized device. Compared with a conventional fluted-wheel fertilizer metering device, the optimized screw device reduced the average discharge error from 8.94% to 3.35% and achieved average CV values of 5.91%, 4.39%, and 4.44% under low-, medium-, and high-discharge-rate conditions, respectively. These results show that optimizing the inclination angle and outlet accumulation length can effectively improve fertilizer discharge uniformity and metering accuracy.