Granular dynamics of cohesive powders in a rotating drum as revealed by speckle visibility spectroscopy and synchronous measurement of forces due to avalanching
H. Yang
G.L. Jiang
H.Y. Saw
C. Davies
Mark Biggs
Vladimir Zivkovic
2134/20679
https://repository.lboro.ac.uk/articles/journal_contribution/Granular_dynamics_of_cohesive_powders_in_a_rotating_drum_as_revealed_by_speckle_visibility_spectroscopy_and_synchronous_measurement_of_forces_due_to_avalanching/9391310
We have used speckle visibility spectroscopy (SVS) and synchronized force measurements to compare the granular dynamics of two cohesive lactose powders, with Sauter mean diameters of ~29 and ~151 μm, in a rotating drum. A load cell (LC) was used to measure forces on the drum mounting frame and enable monitoring of bulk powder motion; SVS is a dynamic light scattering technique particularly suited for studying dynamics in dense, non-ergodic granular systems. Our results reveal that surface slumping and intermittent collisional dynamics in the bulk of the bed are correlated, especially for the fine more cohesive particles (Geldart group C/A boundary), but not as much for the less cohesive larger particles (Geldart group A/B boundary). The specific dissipation energy of the particles in the drum is similar for both powders, and increases linearly with increasing drum speed. However, the dependencies of the load cell and SVS signals on rotation speed have opposing trends for these two powders, indicating different dissipation mechanisms for the different Geldart Groups; collisional dissipation is more important for the Geldart C/A powder, while for the Geldart A/B powder avalanche dissipation is dominant.
2016-03-22 15:02:55
Granular flow
Rotating drum
Cohesive powders
Avalanches
Jamming
Powder technology
Chemical Sciences not elsewhere classified
Mechanical Engineering