Analysis of Flame Topology and Burning Rates

Datasets generated using Direct Numerical Simulation (DNS) are used to investigate the influence of local flame surface topology on global flame propagation. A mathematical framework based on Morse theory is presented and is shown to lead to a classification of all possible types of flame surface topology. A similar mathematical approach is shown to provide insight into the behaviour of the surface density function (SDF) and the displacement speed in the vicinity of flame pinch-off and pocket burnout events. DNS data for a pair of colliding premixed turbulent hydrogen–air flames is used to identify and locate topological points of interest and to determine their frequencies of occurrence on the flame surface. Further analysis of the dataset is carried out to evaluate terms of the SDF balance equation and the displacement speed in the presence of flame–flame interactions. Considerable insight is gained into the underlying mechanisms of flame propagation.