Characterization of intruder particle motion in a bladed mixer

Abstract

Granular mixing is important to many industries, but the mixing process is still poorly understood. In this study, motion of a single intruder particle introduced in a shallow bed of native particles was investigated. A parametric investigation was carried out to quantify the effects of initial intruder particle location, blade speed, and density difference between similarly sized native and intruder particles on the motion of the intruder particle during the mixing process. Intruder particles were color-tagged and videos were obtained from the top free surface of the shallow bed throughout the mixing duration. Additional experiments were performed to investigate the effect of density ratio between the intruder and native particles on the mean radial location (MRL) of the intruder particle. In the shallow bed system, all particles were found to be consistently under the direct influence of the blade and moved in discrete tracks unless randomly excited by the blade or neighboring particles. Intruder particles that were denser than the native particles were found to rotate closer to the hub with a smaller mean radial location, whereas less dense intruders were found to be further away from the mixer center on average. Initial location was important only for the first few rotations, and the blade speed had a negligible impact on the intruder particle flow behavior.