Numerical simulation of a fuel droplet laden exothermic reacting mixing layer

Numerical simulations are conducted of two-dimensional exothermic reacting mixing layers laden with liquid fuel droplets. An irreversible reaction of the form Fuel+r Oxidizer→(1+r)Products+Heat with Arrhenius kinetics is considered where the fuel species consists of both a gaseous fuel stream and liquid fuel droplets. A variety of configurations are simulated including cases for which the droplet species and/or the carrier fuel is either reacting or non-reacting. The droplets are tracked individually in the Lagrangian reference frame while the compressible form of the Navier–Stokes equations together with transport equations for all species govern the gas phase. The simulation parameters study the effects of the fuel composition, reaction stoichiometry, mass loading ratio, droplet Stokes number and the flow forcing amplitude. The simulations reveal that non-reacting carrier fuel configurations fail to achieve robust combustion, suggesting the primary role of carrier gas fuel to the reaction. Local flame extinction is markedly increased for non-reacting fuel droplets due to latent heat effects. In contrast, liquid droplets which contribute fuel to the reaction overcome the associated latent heat effects and show a relatively robust reaction with minimal local extinction.