A Prediction Model for Turbulent Diffusion Flames, Including No-Formation

摘要

A prediction model for turbulent diffusion flames burning gaseous fuels was developed and applied to H2-air flames. In the simplified system of chemical reactions the fast reactions are assumed to be in equilibrium whereas three-body recombinations are treated in nonequilibrium. For the H2-air flames this assumption leads to a description of the reacting system with only two variables: reaction fraction and reaction variable. Two methods of treating such a system in a turbulent flow are discussed. Two sets of equations are complemented with a modified version of the kinetic energy/dissipation rate turbulence model. The NO-formation in such flames can be calculated using the nonequilibrium values (mean values and covariances) of the O and H radicals. The results obtained with both models are compared with experiments and show good agreement.