Determing the drag coefficient of fertilizer grains using stereovision

Increased accuracy in fertilizer spreading performance is required to maximize the farmers’ profit and reduce several ecological effects. To allow for proper spreader calibration, a research system was developed to predict the spread pattern of centrifugal spreaders. By measuring the ejection parameters of the fertilizer grains and applying these in a ballistic flight model, the landing positions of these particles can be calculated, from which the spread pattern can be simulated. Simulations indicate the high sensitivity of the predicted spread pattern to the drag coefficient of the particles. In literature, this coefficient has mostly been determined at terminal velocity and/or for perfectly spherical particles. This paper describes a new method to determine the drag coefficient at velocities similar to those imposed by a centrifugal spreader. The ejection parameters of a single fertilizer particle were determined by means of image processing. Three dimensional information was obtained using a stereo arrangement of high speed cameras. The drag coefficient was calculated by parameter estimation using the registered position of the grain at a discrete distance after ejection. The accuracy of the method was evaluated by simulation. Preliminary experiments with a common type of fertilizer (KAS 27%N) show promising results. However, some modifications are necessary to improve the quality of the data and to shorten the duration of testing.

[1]  Herman Ramon,et al.  DEM simulations of the particle flow on a centrifugal fertilizer spreader , 2009 .

[2]  T. Bruulsema,et al.  Review of greenhouse gas emissions from crop production systems and fertilizer management effects , 2009 .

[3]  Gary H. Ganser,et al.  A rational approach to drag prediction of spherical and nonspherical particles , 1993 .

[4]  N. K. Sinha,et al.  Drag on non-spherical particles: an evaluation of available methods , 1999 .

[5]  Philip M. Haygarth,et al.  Agriculture, phosphorus and eutrophication: a European perspective , 2007 .

[7]  Herman Ramon,et al.  Experimental characterisation of the cylindrical distribution pattern of centrifugal fertiliser spreaders: towards an alternative for spreading hall measurements , 2003 .

[8]  J. R. O'Callaghan,et al.  Aerodynamic properties of grain/straw materials , 1990 .

[9]  Jan Pieters,et al.  A simulation of the influence of spinning on the ballistic flight of spherical fertiliser grains , 2014 .

[10]  J. Englund,et al.  The impact of various parameters on the carbon footprint of milk production in New Zealand and Sweden , 2011 .

[11]  Tony E Grift,et al.  Determining Effects of Fertilizer Particle Shape on Aerodynamic Properties , 1997 .

[12]  Bruno Huyghebaert,et al.  Uniformity of N‐fertiliser spreading and risk of ground water contamination , 2002 .

[13]  O. Levenspiel,et al.  Drag coefficient and terminal velocity of spherical and nonspherical particles , 1989 .

[14]  Julien Dubois,et al.  Two-step cross correlation–based algorithm for motion estimation applied to fertilizer granules’ motion during centrifugal spreading , 2011 .

[15]  Jürgen Vangeyte.  Development and validation of a low cost technique to predict spread patterns of centrifugal fertiliser spreaders , 2013 .

[16]  Dimitrios Moshou,et al.  Prediction of spreading processes using a supervised Self-Organizing Map , 2004, Math. Comput. Simul..

[17]  E. Pattey,et al.  Modeling the Effects of Fertilizer Application Rate on Nitrous Oxide Emissions , 2006 .

[18]  Jan Willem Hofstee,et al.  Handling and spreading of fertilizers part 1: Physical properties of fertilizer in relation to particle motion , 1990 .

[19]  Ian J. Yule,et al.  Accessing Spreader Performance for Variable Rate Fertiliser Application , 2005 .

[20]  Lawrence F. Shampine,et al.  The MATLAB ODE Suite , 1997, SIAM J. Sci. Comput..

[21]  J. De Baerdemaeker,et al.  Calculation of fertilizer distribution patterns from a spinning disc spreader by means of a simulation model , 1996 .