Experimental characterisation of the cylindrical distribution pattern of centrifugal fertiliser spreaders: towards an alternative for spreading hall measurements

The performance of centrifugal spreaders can be evaluated by measuring their fertiliser distribution patterns in spreading halls. Compact experimental equipment was used to measure the tangential and the cylindrical distribution of the particle flow close to the edge of the disc. Additional information on the positions and velocity vectors of the particles when leaving the disc was obtained by photogrammetry. From these data, standard distribution patterns have been computed by means of a computer program simulating the ballistic flight of the particles. Experiments were conducted with a single commercial centrifugal spreader with conical discs, which can be supplied with short or long vanes. Both vane types are combined with two different types of fertilisers. There is a good qualitative agreement between the measured and simulated distributions. Quantitatively, the difference between experimental and simulated distributions amounts to a shift and an expansion in the angular direction and a contraction in the radial direction. Conclusive evidence is reported that the predicted patterns respect trends that can also be observed in experimental patterns due to variations in fertiliser properties or spreader settings. Consequently, the predicted patterns can be used to investigate such trends. Further improvements of the simulation model and/or the implementation of the experimental facility are needed before the proposed evaluation method can completely replace spreading hall measurements. (C) 2003 Silsoe Research Institute. All rights reserved. Published by Elsevier Ltd.