Large Eddy Simulation for Prediction of Entropy Generation in a Nonpremixed Turbulent Jet Flame

Local entropy generation in a turbulent nonpremixed jet flame (Sandia Flame D) is predicted using large eddy simulation (LES) with inclusion of entropy transport. The filtered form of entropy transport equation contains several unclosed source terms which represent irreversibilities due to viscous dissipation, heat conduction, mass diffusion, and chemical reaction. The subgrid scale (SGS) closure is accounted for by the entropy filtered density function (En-FDF) methodology to include complete statistical information about SGS variation of scalars and entropy. The En-FDF provides closed forms for the chemical reaction effects. The methodology is applied for LES of Sandia Flame D and predictions are validated against experimental data. Entropy statistics are shown to compare favorably with the data. All individual irreversible processes in this flame are predicted and analyzed. It is shown that heat conduction and chemical reaction are the main sources of entropy generation in this flame.