DEVELOPMENT OF A FERTILIZER PARTICLE ACCELERATOR

Testing of fertilizer spreaders is traditionally carried out by using the collecting tray method, requiring a large hall to eliminate the in fluence of wind and rain. The Dutch government has announced mandatory periodic testing of fertilizer equipment which could require a signif icant number of these costly halls. Therefore, an alternative method h as been developed which is based on scanning the spreading zone and me asuring the velocity vector and diameter of individual fertilizer part icles, emanating from the spreader. A model then predicts the landing spot of each particle and accumulation of these spots gives the desire d spread pattern. To test the proper functioning of the sensors that a re used to measure the velocity and diameter of the particles, it was found necessary to develop a test device which is capable of dischargi ng fertilizer particles with a realistic velocity and a fixed directio n. The desired maximum launch velocity of the device is 70 m/s, the mo st extreme value that particles reach in practice. The principle of th e accelerator that was developed is similar to that of a disc type spr eader which has been fitted with an encapsulating housing. The machine was tested in combination with an optical device for the measurement of velocity and diameter, at ejection velocities up to 52 m/s. At high er velocities, virtually all fertilizer particles fragmented owing to the severe forces on particles when being accelerated. (C) 1997 Silsoe Research Institute.