CFD simulations of tapered bubbling/turbulent fluidized beds with/without gas distributor based on the structure-based drag model

摘要

The hydrodynamic characteristics of tapered bubbling/turbulent fluidized beds with/without gas distributor are simulated based on the structure-based drag model. Besides the only parameter of gas voidage (epsilon(g)) contained in the original drag model, the heterogeneous drag index (H-d) for the tapered fluidized bed (TFB) also includes the parameter of gas velocity (u(g)) for the axial velocity gradient along bed height. Both the simulations of tapered bubbling and turbulent fluidized beds achieve more accurate predictions than the traditional drag models. There exist dilute center and dense annular regions with solids cycle flow structure in the TFB. The simulation also gives reasonable prediction for TFB without gas distributor, the variation of gas voidage profile reveals gas converging toward bed center with axial location rising. (C) 2019 Elsevier Ltd. All rights reserved.