Advances in Two-Fluid LES of Two-Phase Combustion

Abstract

Recently, large-eddy simulation (LES) was used to study spray-air and coal-air two-phase combustion. Most LES of two-phase combustion takes Eulerian–Lagrangian approach, which needs much more computational time than the Eulerian-Eulerian (E-E) or two-fluid approach. A few studies on E-E LESof two-phase combustion were reported in the literature. In this paper at first previous studies are reviewed. Then, the mathematical models for two-fluid LES of two-phase combustion, proposed by the present author are presented, including filtered controlling equations, specific for full two-fluid and two-fluid-Lagrangian approaches, a two-phase sub-grid scale (SGS) stress model and a SGS combustion model. For the SGS stress model, the present author proposes a two-phase SGS energy equation model, accounting for the interaction between two phases. For the gas-phase combustion model, a second-order moment SGS (SOM-SGS) turbulence-chemistry model, proposed by the present author, is suggested to simulate gas-phase (liquid-fuel vapor or CO and coal-volatile) combustion. Also, for coal combustion, the coal pyrolization and char combustion models are used. These sub-models are separately assessed by comparison with experiments.KeywordsTwo-fluid modelingLarge-eddy simulationTwo-phase combustion