Theory of Attached and Lifted Diffusion Flames

Diffusion flame (DF) attachment and liftoff are examined, leading to (1) explanations of the origins of previous, successful empirical correlations; (2) the discovery of multiple lifting regimes. The latter includes a very slow flow regime, a slow-to-moderate flow regime, and a moderate-to-fast flow regime. Formulas for liftoff height (l̂g)(l̂g) and characteristic flame tip breadth (l̂r)(l̂r) are developed from a combination of the differential and integral form of the conservation equations. These formulas are compared with numerical solutions of the same equations.