Large eddy simulation of polydisperse particles in turbulent coaxial jets using the direct quadrature method of moments

Abstract

Modeling coal particles in turbulent coal flames is a challenging but nonetheless critical step for predicting flame characteristics. Traditional approaches such as Reynolds-Averaged Navier-Stokes (RANS) coupled with Lagrangian solvers are unable to correctly predict particle concentrations and velocities in complex systems. This study shows how Large Eddy Simulations (LES) coupled with an Eulerian solver can address those issues. Previous Direct Numerical Simulations and Stokes number analysis suggest that LES has the capabilities to resolve all the turbulent length scales affecting coal particles in a coal flame and could therefore lead to more accurate simulation. The effects of fluid aerodynamics on the particle motion in the near field region of non-reacting coaxial particle-laden jets were simulated using LES. The Direct Quadrature Method of Moments (DQMOM) was used to track the particle phase in an Eulerian framework. Simulation results were compared to experimental data and accurately modeled a wide range of particle behaviors, such as particle jet waviness, spreading, break up, particle clustering and segregation, in different conditions. Simulations also predicted the mean axial velocity along the centerline for both the gas phase and the solid phase with a maximum error of 12% relative to experimental data. This study therefore provides a solid validation of the LES with DQMOM approach to model particles in turbulent flows and justifies its use for coal flame simulations.