DOI: 10.1615/TSFP3
UNSTEADY FLOW EVOLUTION AND FLAME DYNAMICS IN A LEAN-PREMIXED SWIRL·STABILIZED COMBUSTOR
SINOPSIS
A comprehensive numerical analysis has been conducted to study the unsteady flow evolution and flame dynamics in a lean-premixed (LPM) swirl-stabilized combustor using a large-eddy-simulation (LES) technique along with a level-set flamelet library approach. Emphasis is placed on the key mechanisms and operation parameters responsible for driving combustion oscillations. Results indicate that the inlet air temperature and equivalence ratio are the two most important parameters determining the stability characteristics of the LPM combustor. A slight increase in the inlet air temperature across the stability boundary leads to a transition from a stable to an unstable flame and consequently a sudden increase in acoustic flow oscillation. Several prevailing processes involved in the flame bifurcation phenomenon are identified and quantified. In addition, the mutual coupling between the heat release in the flame zone and the flow development is carefully examined under both stable and unstable operating conditions.