Direct Numerical Simulation of Nonpremixed Flame Extinction by Water Spray

The interaction of turbulent nonpremixed flames with fine water spray is studied using direct numerical simulations (DNS) with detailed chemistry. The study is of practical importance in fire safety devices that operate in the mist regime, as well as an inexpensive temperature control mechanism for gas turbines. The implemented computational methods for the Lagrangian particle-in-cell spray droplet representation and modified characteristic boundary conditions for spray-laden reacting flows are briefly described. The model configuration is a two dimensional ethylene-air counterflow diffusion flame at moderate strain rate. Laminar and turbulent flame simulations are performed with various water loading conditions. Comparison of various simulation cases highlights the flame weakening characteristics due to fluid dynamic strain and water spray evaporation. A modified mixture fraction variable defined in our earlier study [1] is applied to provide correct physical description of the flame response by accurately capturing the flame locations. Findings from this study provide a better understanding of interaction between thermal and aerodynamic quenching in turbulent flame dynamics.