A numerical study of a bluff-body stabilized diffusion flame .2. influence of combustion modeling and finite-rate chemistry

This is the second and last part of a paper on numerical prediction of a bluff-body stabilized turbulent diffusion flame, of syngas and air. Part 1 investigates the effect of the turbulence model and boundary conditions. This part considers the influence of the combustion model and the effect of finite-rate chemistry. Three combustion models, the eddy dissipation concept (EDC), the assumed-pdf method and the pdf-transport method are compared. A comparison of predictions based on fast and finite-rate chemistry are carried out for the eddy-dissipation concept. All results are based on the Reynolds-stress-equation (RSE) model for the turbulence. When fast chemistry is assumed, the pdf-transport method predicts the mean and rms mixture fraction and mean temperature better than the EDC model and the assumed-pdf method. However, the pdf-transport method underpredicts the peak value of H2O, suggesting-that the reaction rate is actually underpredicted. When finite-rate chemistry is accounted for in the EDC model, the temperature and the H2O mass fraction are both in very good agreement with the experimental data.