INFLUENCE OF DIFFERENTIAL DIFFUSION ON LOCAL EQUILIBRIUM AND SUPER-EQUILIBRIUM COMBUSTION IN TURBULENT NON-PREMIXED FLAMES

摘要

Turbulent combustion can lead to very specific phenomena. One of them is called super-equilibrium combustion. In many applications, authors have indeed seen temperatures higher than those obtained by thermodynamic equilibrium. In the present work, this effect is studied for diluted hydrogen/air flames using DNS computations taking into account differential diffusion. The results show that transport phenomena lead to local accumulations of reactants or dilutants. These changes in the relative composition of the mixture induce large modifications of its thermodynamic properties. It becomes therefore possible to obtain temperatures higher than those computed by neglecting these modifications of the locaf dilution rate.