ABSTRACT
In fl ames formed by the condensed or gaseous fuel sources burning in the atmosphere, the combustion process is controlled by the mixing process rather than the rate of chemical reaction. The most familiar example is a candle fl ame, where the fl ow fi eld is laminar and mixing occurs by molecular diffusion. Burke and Schumann [1] developed a theory of simplest laminar diffusion fl ames, where a gaseous fuel jet was issued into air fl owing at the same velocity in a wider duct, with an infi nitely thin fl ame-sheet model. In diffusion fl ames, however, the fl ame structure (i.e., spatial variations of velocity, temperature, and species concentrations) determines various characteristics, such as fl ame stabilization and pollutant formation. A detailed understanding of the structure, particularly the chemical aspect, of diffusion fl ames is only being achieved recently. Today, it is common to calculate the coupled time-varying fl uid dynamics, heat transfer, and mass transfer with numerous elementary reactions throughout the fl ame. These results are then compared with the detailed, nonintrusive laser-based measurements of velocity, temperature, and species concentrations, even within the fi nite-thickness reaction zone itself.
