Characterizing spray flame-vortex interaction: A spray spectral diagram for extinction

The flame-vortex interaction is a preferred configuration for the understanding of flame-turbulence interaction as well as for the development of turbulent combustion models. This configuration has been extensively studied in the literature for gaseous flames. In the present work, we extend this analysis and develop a spectral diagram for the description of spray flame-vortex interaction in analogy to purely gaseous flames in the limit of momentum equilibrium. The focus is hereby on the analysis of competing time-scale effects that are associated with droplet evaporation, mixing and reaction chemistry. Through this analysis, a new extinction scenario is identified that is specific to spray flames as a result of fuel depletion. The derived spectral diagram is confirmed by numerical investigations for n-dodecane counterflow spray flames interacting with a pair of vortices. The different extinction scenarios and their dependence on the evaporation time are numerically studied and verified.