CFD-DEM investigation of gas–solid swirling flow in an industrial-scale annular pipe

Abstract

Swirling gas-particle flow has been prevalently utilized in many industrial applications due to the obvious advantages of high particle dispersity, small pressure drop and low power consumption. In this work, numerical simulation of the swirling gas–solid two-phase flow in the three-dimensional industrial-scale annular pipe installed with a helical swirler is carried out via computational fluid dynamics coupled with discrete element method. The mixing characteristics of two-axial jets together with the particle-scale information of solid phase are fully investigated. The results show that the high Reynolds number of gas phase is observed above the swirl generator, while high turbulent Reynolds number of gas phase mainly appears in the core region of the mixing zone. The existence of the swirler vorticity in the high-velocity jet increases the strain rate of gas phase. The cross-section distribution of the particles always follows the normal distribution pattern, and the velocity components of the outermost particle are dramatically higher than those in the core region. Due to the entrainment effect of swirling gas flow, the velocity and dispersion width of the particles increase when moving downward. Swirling flow of gas phase obviously impacts the particle velocity and entrained number within the height of the z/H = 0.2 to 0.1 but only affects the particle entrained number in the range of z/H = 0.1 to 0.