Calibration of a Spinning Disc Spreader Simulation Model for Accurate Site-specific Fertiliser Application

A simulation model of a spinning disc fertiliser spreader developed for incorporation into an automatic control system design is described. Comparisons of the model simulation results to real measured results showed unacceptably high discrepancies between the two. Discrepancies were significantly reduced to acceptable levels when the parameters of the particle ‘landing area’ on the disc were used in the calculations rather than those of the orifice area, thus confirming the validity of the model. Particle ‘landing area’ is a manifestation of phenomena unaccounted for by the model and is dominated by the various particle interactions that occur during flow. Particle interactions are sensitive to spreader configurations, fertiliser characteristics as well as environmental factors. Calibration of model was performed to quantify dependence of ‘landing area’ parameters on a variety of spreader settings under controlled environmental conditions and for one fertiliser type. Achieved calibration curves can be used in a control system design to determine necessary adjustments to other control parameters to maintain shape of the distribution pattern when flow rate is adjusted.