Estimation of two-dimensional fertiliser mass flow distributions by recording granule impacts
Abstract
This paper presents a new method to simultaneously measure the horizontal and vertical
distributions of the mass flow in the vicinity of the spinning disc of a centrifugal fertiliser
spreader. The method consists in recording granule impacts on a cylindrical vertical screen
placed around the disc. The screen is covered with a paper band, a carbon film and a
protective coat, so that granule shocks against the screen produce impact marks on the
recording paper band. A mathematical model is used to estimate the local impact density by
correcting the bias due to impact overlapping. Algorithms are here developed to process the
recording band, taking into account its location with respect to the spreading device. The
distribution of the mass flow is studied for two fertilisers. Our findings demonstrate that
processing impact record clearly distinguishes the horizontal and vertical distributions of the
mass flow for a compound fertiliser NPK and potassium chloride. For the horizontal
distribution, comparisons are carried out with results deduced from a traditional
compartmented ring. The vertical distribution of the mass flow is also studied. This new
approach paves the way for the design of alternative tests and diagnostic tools to characterise
centrifugal fertiliser spreading.