Mechanisms of premixed turbulent swirling flame stabilization*

The presentation focus on the mechanisms of flame stabilization for premixed swirling flames on a laboratory scale experiment. A set of local contributors responsible of flame stabilization are identified from literature review. These local explicit (temperature, velocity,… ) or implicit (flame stretch, equivalence ratio, flame surface speed) local contributors are further investigated with numerical simulation of a premixed swirling flame.  They are computed on flame surfaces and their distributions are obtained. Theoretical expressions are derived which focus on the flame surface, flame speed and velocity budget to guide the analysis. It indicates that the flame stabilization can be described with instantaneous, steady-state and fluctuating budgets respectively. Selected budgets’ terms are computed with the numerical simulations and indicate that the flame is stabilized by flow effect including low velocity region and turbulence/acoustic fluctuation region. The thermal diffusion term of the flame speed originating from the burnt gas of the recirculation zone and the combustion reaction effects are studied as part of the mechanisms of stabilization.