Flame propagation patterns and local flame features of an annular combustor with multiple centrally staged swirling burners

In this paper, the transient ignition process of an annular combustor with 16 centrally staged swirling burners is experimentally investigated to study the mechanism of burner-burner flame propagation. The flame propagation patterns are studied by high-speed imaging. Three typical patterns of the burner-burner flame propagation are identified: the kindled-swirling pattern, entrained-swirling pattern, and sweeping pattern. The patterns are featured with different flame paths of motion. For fixed flow rates, the paths of motion are mainly determined by the overall equivalence ratio Φ. Furthermore, during the burner-burner flame propagation, the effect of the flow field on the local flame fronts is analyzed by Mie scattering and particle image velocimetry (PIV) methods. The PIV results show that the flame paths of motion are greatly influenced by the flow structure of the annular combustor. The optical diagnosis of the flame-flow interaction provides new insights into the ignition dynamics of the centrally staged annular combustor.