Turbulence structure of the solid phase in transition region of a circulating fluidized bed

Turbulence structures in transition region were characterized in a circulat ing fluidized bed (CFB) with square cross section. The investigations were carried out using a Particle Dynamic Analyzer (PDA). Both the axial and lat eral velocity profiles of the solid phase were obtained. The axial profiles show the core-annulus structure in this region. Temporal evolutions of the particle velocity fluctuation indicate their great agitation and non-homog eneity with time and space coordinate. The studies on turbulent density and turbulent energy illustrate that the turbulence in the CFB is an anisotrop ic turbulence, and the particle turbulent density decreased sharply as the measurement points move away from the wall. To further understand the micro structure of the particle velocity fluctuation, wavelet analysis was also a dopted. The vivid imagines show that it is an anisotropic turbulence at all scales and its fractal and dissipative structure. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.