Physical mechanisms that cause intermittency that presages combustion instability and blowout in a turbulent lifted jet flame combustor

The physics of intermittent dynamics that presages the onset of impending combustion instability and blowout in a turbulent lifted jet flame combustor is investigated. It is observed that the transition from combustion noise to combustion instability happens via intermittency while varying the relative location of the burner inside a confinement as a bifurcation parameter. For further change in burner location past the condition of combustion instability, the intermittency before the flame blows out is once again observed. The authors show that the coupled interaction of flow, flame dynamics, and combustion chamber acoustics is the physical reason for the occurrence of intermittency prior to combustion instability. In contrast, intermittent dynamics that presages blowout occurs due to the interplay between flame blowout precursor events and the driving of high-amplitude oscillations as the flame propagates towards the burner.