Flame configurations in an annular swirl burner

This paper describes an experimental investigation of flame configurations in a swirling, lean premixed combustor. The flame configuration or stabilization location within the combustor has important influences upon a variety of combustor performance metrics, such as combustion instability limits and pollutant emissions. Flame configurations were mapped for preheat temperatures ranging from 200 to 500 deg F while varying equivalence ratio from 0.40-0.70. Within this operational space, the flame exhibits four basic configurations. We show that the transitions from one flame configuration to the next is essentially a flame extinction problem, and that the sensitivity of these transition points to fuel/air ratio and preheat temperature can be reasonably captured with extinction strain rate calculations.