Large-eddy simulation (LES) of particle-laden, swirling flow in a coaxial-jet combustor is performed. A mixture of air and lightly loaded, spherical, glass-particles with a prescribed size-distribution enters the primary jet, while a swirling stream of air flows through the annulus. The incompressible, spatially filtered Navier-Stokes equations are solved on unstructured grids to compute the turbulent gas-phase. A Lagrangian formulation and an efficient particle-tracking scheme on unstructured meshes is developed to compute the dispersed phase. The particles are treated as point sources and influence the gas phase only through momentum-exchange terms. The particle-dispersion characteristics are examined in detail; in particular, the dependence of particle trajectories and residence times upon particle sizes is emphasized. The mean and turbulent quantities for the gas and particle phases are compared to experimental data and good agreement is obtained. The LES results are significantly more accurate than the Reynolds-averaged Navier-Stokes equation (RANS) predictions of the same problem. Insight into the two-phase swirling flows is obtained through the residence-times and particle velocity-diameter correlations.
Bibliographical noteFunding Information:
Support for this work was provided by the United States Department of Energy under the Accelerated Strategic Computing Initiative (ASCI), program. The computer resources provided on Blue Horizon at San Diego Supercomputing Center and ASCI Frost at Lawrence Livermore National Laboratory, CA are greatly appreciated. We would also like to thank Prof. Martin Sommerfeld for providing detailed experimental data in this configuration. We are indebted to Dr. G. Constantinescu and Mr. G. Iaccarino for their help at various stages of this study.
- Particle-laden flows
- Swirling flows
- Unstructured grids