Rheological effects of a gas fluidized bed emulsion on falling and rising spheres

To enable the mechanistic description of mixing larger particles in gas-fluidized beds models (e.g. fuel combustors), knowledge about rheology bed emulsion is required. Here, it crucial to determine drag on large fuel-alike particles. This work presents experimental fate 13 different solid spheres falling or rising through a air and glass beads at minimum fluidization. The trajectories tracer are highly resolved (sampling rate 200 Hz) by means magnetic particle tracking, this previously unmet accuracy allows disclosing complex rheological behavior gas-solids fluidized emulsions terms immersed objects. reveal that none tracers reach terminal velocity during their fall rise bed. shear stress obtained force solving equation motion for tracer. data particularities clear differences its effect When studying over characteristic each tracer, can be seen dominated yield stress, with somewhat smaller contribution stress. For last almost negligible. show strong interaction emulsion, resulting fluctuating which increases size density. stagnation some low rates reveals viscoplastic exhibiting typical showing dependence diameter buoyant concept gravity used order introduce normalized provides additional verification observations relation influence relative density