Large-Eddy Simulation of Particle Diffusion in a Particle-laden Swirling Jet

Abstract

Large-eddy simulations (LES) are applied to particle-laden swirling jets, and effect of the swirl on particle dispersion is investigated. The trajectories of all particles are individually pursued with a Lagrangian method. The particles with different diameters are uniformly injected into a non-swirling flow or swirling flows with different swirling numbers. The results show that the trajectories of the particles largely differ depending on their diameters. In swirling jets, the peak of particle number density for small particle is located on the central axis, whereas that for larger particles is shifted outward by the centrifugal force. However, the larger particles, which migrate outward in the upstream region, tend to gradually migrate inward toward downstream, and this trend is remarkable as the particle diameter decreases. This is due to the fact that the direction of the particle migration in the downstream region is dominated by the turbulent motions, which act to transport the smaller particles inward in wide range of the swirling jets.

Keywords

• swirling flow
• two-phase turbulence
• large-eddy simulation
• particle dispersion