The swirl combustor model of aircraft engine under fuel-lean condition was characterized by planar laser-induced fluorescence (PLIF) technique. By taking PLIF measurements of OH and CH2O simultaneously

the transient structures of the reaction zone and preheat zone were investigated under various operation points. By applying proper orthogonal decomposition (POD) method to the OH PLIF data

the main dynamics modes of the swirling flame were extracted

and by applying extended proper orthogonal decomposition (EPOD) method

CH2O PLIF signal distribution for each POD mode was unveiled. The experimental results indicate that as the thermal power of the combustor increases

the time-averaged structure and dynamics modes experience notable transitions. As the flame elevated

the flame exhibits stronger axial instability

while the deformation caused by precessing vortex core (PVC) is decreased. At relative high thermal power

unburnt fuel emerges in the external recirculation zone (ERZ).