Influência do perfil de aleta nos parâmetros de lançamento de fertilizante em distribuidores centrífugos

Abstract

Centrifugal spinner spreaders are one of the most used machinery for agricultural fertilizer and corrective powder distribution, mainly because of its high performance operation. Granular media indetermination and distribution process characteristics molded the throwing system the most complex device on the equipment. It propelled several decades of modelling and through studies about distribution parameters, grain movement on and off the machine and how it affects the material deposition on the ground. Despite the scientific effort, few experimental researches were conducted of the vane profile effect on fertilizer distribution. Resorting to basic granular mechanics and several applied studies on distribution systems the dependence of the resistance forces on transversal vane geometry capable of altering exit properties was examined. Two variables were chosen to perform an experiment in a controlled environment able to measure grain exit angle, three profiles: L, C and V and two rotational speeds. Data was collected on long photographic exposures that embedded particle trajectories on the pictures. The tests provided 54 exposures, these 18 were analyzed resulting in 861 trajectories and angles identified. Data was submitted to variance analysis that detected significant differences between V and both L and C shapes, showing smaller values for V profile. An examination of the coefficient of variation of all the geometries pointed to a major reduction of both V and C if compared to L shape. Smaller quantities of the closed V form combined with an analysis of the mathematical modelling led to the conclusion that resistance forces are function of the transversal geometrical profile. Meanwhile, the coefficient of variation pointed out that particle restraint is more valuable to uniformity that the imposing of resistance forces.