Large-Eddy Simulation of Pollutant Emission in a DOE-HAT Combustor

Large-eddy simulation (LES) of turbulent premixed reacting flow in a DOE-HAT gas turbine combustor has been carried out to evaluate the use of LES to study combustion dynamics and to predict pollutant emission as lean blowout (LBO) is approached. A model for the subgrid turbulent kinetic energy is used to close the subgrid stresses and heat flux in the LES equations. A thin-flame turbulent propagation model is combined with a mixture-fraction-based flamelet library to predict the turbulence-chemistry interactions. Production of pollutants such as oxides of nitrogen (NO x ) and carbon monoxide (CO) is predicted using this model and compared to experimental data. Good agreement is obtained for CO and NO x emission as a function of equivalence ratio, and the simulations predict the observed increase in CO emission as LBO is approached. Simulations also show that the dynamical (unsteady) interactions increase in intensity as LBO is approached.