Large Eddy Simulation of a Syngas Jet Flame: Effects of Preferential Diffusion and Turbulence-Chemistry Interaction

摘要

A large eddy simulation of the turbulent syngas non-premixed jet flame of Sandia ETH/Zurich B is conducted using an in-house version of FireFOAM, a fire simulation solver within OpenFOAM. Combustion is modeled using (i) the newly extended eddy dissipation concept for the large eddy simulation published by the authors' group, (ii) the 74-step CO-H-2-O-2 mechanism and (iii) the relatively simple tabulated chemistry approach. The effects of the nonunity Lewis number and thermal diffusion (=Soret diffusion) are considered in the mass fraction and enthalpy equations. Systematic validation and model sensitivity studies have been conducted against published experiments of the turbulent syngas diffusion flame from the international workshop on measurement & computation of turbulent flames (TNF workshop). The predictions were in very good agreement with the relevant experimental data. The axial position of peak H2O moved toward the nozzle direction owing to the different diffusion coefficients of H-2. In the radial direction, the effect of thermal diffusion was observed at x/d 20, whereas those of the nonunity Lewis number and difference in chemistry were found at x/d 40. After considering the effects of the nonunity Lewis number and thermal diffusion, as well as the detailed reaction mechanisms, the results were slightly better than those obtained under previous numerical conditions.