Abstract
The detailed behavior of gaseous and spray lifted flames are studied by two-dimensional direct numerical simulations (DNS), and the characteristics are investigated in terms of two key variables for flamelet modeling. The results show that both the gaseous and spray lifted flames are partially premixed flames, in which premixed and diffusion flames co-exist and the premixed flame stablizing the flames precedes to the diffusion flame. The premixed and diffusion flames in the partially premixed flame can be predicted by the flame index. Although the flamelets in the diffusion flame of the gaseous lifted flame are modeled by flamelet model, thoses on the spray lifted flame are not. To account for the flamelet characteristics of the spray lifted flame, the flamelet/progress-variable approach needs to be introduced.
