Scale Analysis of Pulverized Coal Combustion

Paper from the AFRC 2018 conference titled Scale Analysis of Pulverized Coal Combustion

Large eddy simulation (LES) is becoming a more powerful tool than Reynolds-Averaged Navier-Stokes (RANS) for predicting the flame characteristics of coal combustion. Previous studies verified that RANS fails to capture the particle dispersion process in turbulent flows which is critical for accurate simulations. LES coupled with Direct Quadrature Method of Moments (DQMOM) was carried out to simulate pulverized coal jet flames in the large laboratory scale furnace-100 kW down-fired oxy-fuel combustion (OFC) furnace.; Previous studies showed that this high-fidelity methodology can provide a deeper understanding of very complex coal flames. The effects of unresolved turbulent scales on the particle motions were analyzed by Stokes number.; The analysis showed that the sub-grid scales did affect the trajectories of small particles while had little effects on large particles. Since small particles are important for flame stability, sub-grid scale velocity models are necessary to fully resolve the particle motions.