Numerical simulations of turbulent jet flames with non-premixed combustion of hydrogen-enriched fuels

Large-eddy simulation is conducted to study the turbulent combustion processes of hydrogen and syngas flames. The subgrid scale momentum transport is performed with a one-equation model using the subgrid scale turbulent kinetic energy, while the linear-eddy model is employed to represent the scalar transport. Reduced chemical kinetics is used to describe the flame chemistry with the extended Zeldovich mechanism to account for the thermal formation of NOx. Results show the effects of the hydrogen content and of the Reynolds number on the characteristics of the flames. Higher hydrogen content contributes to increase the heat released after combustion leading to higher temperature peaks and thicker shear layers. The presence of CO in the fuel stream affects the flame dynamics with the development of a more vortical and wrinkled flow field. The vorticity field and turbulence/chemistry interactions are also discussed. Scalar profiles and comparison against experimental data are presented where a reasonable agreement is observed.