抄録
Three-dimensional numerical simulations were carried out on dense gas-solid flows for the purpose of investigating the effect of ship rolling motion on circulating fluidized beds (CFBs). Because our research was intended for numerically modeling of realistic CFBs, instead of using a Eulerian-Lagrangian model, a two-fluid model and its sub-models based on the kinetic theory of granular flows were employed for the present gas-solid system in order to reduce computational time. From the numerical results, it was found that the fluidized states under the rolling conditions were obviously different from those in the upright CFBs. Under rolling cases, in comparison to an upright CFB, the amount of solids accumulating at the lower part of a riser increased and solid circulation fluxes markedly decreased. These results qualitatively agreed with experimental observations. To find out the relationship between fluidized states and rolling motion, we examined the external forces, especially drag force, acting on the solid phase per unit mass. In the case of the upright CFB, the horizontal direction components of the drag force were much smaller than that in the vertical direction. On the other hand, it was found that there was significant drag force acting on the solid phase not only in the direction of the riser axis but also in the rolling direction at the lower part of the riser in the rolling CFB. Therefore, it may be inferred that the drag force component in the rolling direction influences the decrease of solid circulation fluxes.
