Two-Dimension Numerical Simulation Of Fluid Dynamics In Gas-Solids Turbulent Fluidized Bed

Since year 1985, the research of turbulent fluidization has attracted much attention of researchers and scholars. Turbulent fluidization is a flow which sandwiched between bubble fluidization and fast fluidization. Compared with bubble fluidization, turbulent fluidization has some advantage: gas and solid exercise intensely, gas contact with solid fully, it has good properties of heat transfer and mass transfer, and the temperature distribution in the bedsurface become uniformity. Meanwhile, because of the bubble's collapse, there are no large air bubbles in the turbulent fluidized bed, which results in smooth steady operation. In recent years, the turbulent fluidized bed is applied to all kinds of industry more and more widely. Owing to different experiment condition and experimental method, which lead to different results in the flow quality. Along with will develop CFD, there are more and more researchers begin to study two phase flow by the numerical simulation, but little effort in turbulent fluidized bed.The gas-solid flow behavior in the two-dimension turbulent fluidized bed was simulated using the two-fluid model. The kinetic theory of granular flow was applied to describe the granular stress to close the governing equations. The interaction between gas and particle was described using the drag model, and the two phase flow turbulence was simulated using k ?εturbulent model. The solids volume fraction was high in the dense section of turbulent fluidized bed, and the frictional stress between particles was considered. The pressure-velocity coupling was obtained by using the phase coupled SIMPLE algorithm.The results showed that the bed homogeneous expansion with the process of the two-dimension gas-solids fluidization, after the fluidized bed access into turbulent fluidization, the bedsurface decrease slightly and then in basically stability; the peak concentration of particle was along the wall region, while the concentration had no obviously change along the central region to the wall boundary layer; the velocity gradient had significant change along the wall to wall layer, while the wall region had minimum velocity. Simultaneously, the fluidtexture of particles in turbulent fluidized bed was circulating flow structure, while the central region was upward flow and the wall region was downward flow. It also shows that the concentration of solids and velocity of particles is symmetrical about fluidized bed centerline in the turbulent fluidized bed, but it doesn't homogeneous distribution along the axial direction.