Statistical analysis on the forced dynamic of internally-staged-swirling stratified flame

To understand the dynamic mechanism of internally-staged-swirling stratified flame used in civil aero-engine low emissions combustor, high-speed CH^* chemiluminescence images of this swirling flame fueled with propane were recorded under the forced condition with 100Hz frequency. Then the temporal and spatial dynamic features of the flame could be extracted by using statistical analysis of proper orthogonal decomposition (POD). The analysis results indicated that the most important 4 dynamic modes in the swirling flame are axial vibration, radial vibration, flame shedding and asymmetric helical motion, respectively. And the axial vibration of mode 1 and radial vibration of mode 2 have significant correlation. The POD analysis could be an effective method for the mechanism exploration of combustion instability in the internally-staged lean premixed combustion.