Numerical Simulation of Premixed Flame Quenching in the Broken-Reaction-Zone Regime

Lean perfectly premixed flame propagation in a swirling flow dump combustor is studied. The emphasis is on flame propagation in the Broken Reaction-Zone (BRZ), where the reaction zone thickness (δF) is larger than the Kolmogorov scale (η). The Linear-Eddy Mixing (LEM) model is used to simulate subgrid interactions between the flame structure and the unresolved turbulent structures within the framework of a large-eddy simulation (LES) approach. A real case scenario is studied: the propagation of a lean premixed flame in a dump combustion chamber where heat losses at the walls are taken into account via the use of a simple heat loss model. Results show flame lift-off, caused by flame quenching, for low equivalence ratio (Φ=0.45). The dynamics of flame quenching, and the subsequent flame lift-off, can be linked to the natural combustion chamber dynamics. The frequency of flame lift off is equal to the half-first longitudinal combustion chamber oscillation mode. I