Granular temperature distribution in a gas fluidized bed of hollow microparticles prior to onset of bubblingL. Xie1, M. J. Biggs1, D. Glass1, A. S. McLeod1, S. U. Egelhaaf2, 3 and G. Petekidis2
1 Institute for Materials and Processes, University of Edinburgh, King's Buildings Mayfield Road, Edinburgh, EH9 3JL, UK
2 School of Physics, University of Edinburgh, King's Buildings Mayfield Road, Edinburgh, EH9 3JL, UK
3 School of Chemistry, University of Edinburgh, King's Buildings Mayfield Road, Edinburgh, EH9 3JL, UK
received 21 October 2005; accepted in final form 21 February 2006
published online 15 March 2006
It has been unclear whether bubbles are required to induce particle velocity fluctuations in gas fluidized beds (FBs). We show that bubbles are not necessary by applying diffusing-wave spectroscopy to particles whose minimum bubbling velocity is approximately 5 times that of the minimum fluidization velocity. Fluctuations are first observed at or just above fluidization and increase in magnitude with superficial velocity. The distribution of velocity fluctuations in the bed is also presented: they are symmetrical about the centreline where they are maximal and increase with height above the distributor.
45.70.Mg - Granular flow: mixing, segregation and stratification.
47.55.Kf - Particle-laden flows.
42.62.Fi - Laser spectroscopy.
© EDP Sciences 2006