Nonlinear self-excited thermoacoustic oscillations: intermittency and flame blowout

摘要: Nonlinear self-excited thermoacoustic oscillations appear in systems involving confined combustion the form of coupled acoustic pressure and unsteady heat release rate. In this paper, we investigate nonlinear transition undergone by to flame blowout via intermittency, response variation location source with respect field confinement. A ducted laminar premixed conical flame, stabilized on a circular jet exit fully developed velocity profile, was investigated. Transition limit cycle from non-oscillatory state observed occur subcritical Hopf bifurcation. Limit underwent further bifurcation quasi-periodic characterized repeated formation elongated necks that pinch off as pockets unburned fuel-air mixture. The loses stability, resulting an intermittent identified type II through recurrence analysis phase space trajectories reconstructed time trace. state, undergoes lift-off reattachment. Instantaneous images suggest behaviour is influenced flow dynamics.