FLOW BEHAVIOR OF DENSE CLUSTERS IN RISER
The velocity, phase fraction and fluctuation velocity of dense clusters are obtained by analysis of transient velocity signals from laser Doppler velocimeter The local velocity of dense clusters increased linearly with superficial gas velocity, while the cross sectional average solids fraction influence the velocity of dense clusters insignificantly A Boltzmann function is used to describe the velocity radial distribution of dense clusters The radial distribution of the phase fraction for dense clusters is described by using an exponential function With the increase of cross sectional average solids fraction, the local phase fraction of dense clusters increases and the area controlled by dense clusters is enlarged The turbulence intensity of dense clusters is highest in the center of the bed while decreases towards the wall