Mass flow measurement of granular materials in aerial application - Part 2: Experimental model validation

A system was developed to measure the mass flow of granular fertilizer mate rial in aerial spreader ducts. The flow process was regarded as the sequent ial passage of clusters containing multiple particles with varying diameter s. An optical sensor was used to measure the cluster lengths on the fly. In a low-density flow regime, the diameter of each particle could be measured individually (this is called the "single-particle approach"). After conver sion to a volume of a sphere and multiplication by the true material densit y, the mass flow could be computed In a high-density mass flow: regime (cal led the "mass flow approach"), particles form clusters, and cluster lengths would be measured instead of particle diameters. The first step in perform ing mass flow measurement was to develop a reconstruction algorithm that es timates the number of particles in a cluster from the measured cluster leng th. This algorithm, called the Exponential Estimator; was developed using s imulation and is reported in Parr 1. This article, Part 2, describes the us e of the mass flow sensor as well as the reconstruction algorithm to assess the accuracy of the complete system. Tests were carried out under laborato ry conditions, using mass flows of spherical particles as well as urea fert ilizer under varying flow velocities and densities. The mass flow of identi cal spherical particles of 0.45 mm diameter was measured with an accuracy o f 3%, even under high-density flow conditions. For granular fertilizer the flow was measured with an accuracy of 2% for high-density flows and 4% for low-density flows.