On the dynamics of spray flames in turbulent flows

Unsteady turbulent spray-flame structures were computationally investigated, employing the same flow configuration used in previous studies for analyzing the structure of gaseous turbulent flames. The presence of a recirculation zone, which is common in jet engine combustion chambers, has a significant role in spray and flame dynamics, diverting the flame in a cyclic motion. Two repetitive developmental stages of flame structures were identified and analyzed. Droplet grouping was found in the vicinity of large vortical structures, and flames surrounding groups of droplets were identified. Backflow of droplets was found to have ligament structures, similar to those found in turbulent shear flow. The local statistics of fuel droplet dispersion is discussed. A new approach is used to investigate the unsteady changes in flame structure by reducing the dimensionality of the problem, revealing low frequency flame repetitive motions, while retaining its turbulent characteristics.