Simulations of Reacting Droplets Dispersed in Isotropic Turbulence

Abstract

Several important issues pertaining to dispersion and polydispersity of evaporating and reacting fuel droplets in forced turbulent flows are investigated. The carrier phase is considered in the Eulerian context and is simulated by direct numerical simulation. The dispersed phase is tracked in the Lagrangian frame and the interactions between the phases are taken into account in a realistic two-way coupled formulation. It is assumed that combustion takes place in the vapor phase and is described as fuel -f oxidizer —> products + energy. The resulting scheme is applied for extensive simulations of a forced, isotropic, low Mach number turbulent flow laden with a large number of fuel droplets. Here the results are presented for different values of the mass loading ratio and the heat release coefficient. The combustion process is significantly affected by the rate of evaporation and the fuel vapor participates in the chemical reaction almost immediately after its production. A strong correlation is observed between the droplet concentration and the reaction rate. The results are also used to discuss the temporal evolution of the mean temperatures and the mean mass fractions, as well as the role of the preferential distribution of the droplets.