Discrete element method modelling of a centrifugal fertiliser spreader

Experimental testing and calibration of new machines and fertiliser can be costly and time consuming. Standard centrifugal fertiliser spreaders are designed to achieve a uniform distribution across the entire field. Fruit trees, however, are planted in rows and it would be advantageous to concentrate the fertiliser closer to the tree trunk and hence the root system. This could reduce the amount of fertiliser needed and will also reduce the negative environmental impact. A discrete element method (DEM) model of a centrifugal fertiliser spreader was developed. A sensitivity study was used to determine the DEM parameters by comparing the results to experimental results. The effects of the disc speed, feed position, feed rate and vane angle on the spread pattern were investigated experimentally and compared to the DEM results. A deflector plate was designed to separate the flow into two paths along the tree lines. The DEM results of the deflector were compared to the experimental results. It was shown that the DEM model can be used to make both qualitative and quantitative predictions of the spread pattern under different spreader settings. The model could also accurately predict the effect of the deflector on the spread pattern. This indicates that DEM can be a powerful tool in the development of new spreader concepts.

► DEM parameters from a sensitivity study and comparing predictions to experimental results.
► The influence of machine settings investigated.
► Good qualitative and quantitative correlations with the measurements.
► Predictions & experimental results of deflector plate to split flow along tree lines gave required pattern.
► DEM is a valuable tool for developing fertiliser spreaders saving development time and money.