Dynamic modal analysis of diffusion flame under acoustic excitation
To investigate the combustion instability of diffusion flame,high-speed image of the bluff body turbulnce diffusion flame were recorded under different acoustic frequencies excitation.And the temporal and spatial dynamic features of the flame could be extracted by using dynamic modal decomposition(DMD).The results show that the unexcited flame is mainly composed of low-frequency oscillations below 50 Hz,and there is an obvious longitudinal oscillation mode around 15 Hz.The external acoustic excitation will cause longitudinal oscillations at the excitation frequency,its half frequency or its double frequency,but will not change the spatial structure of other frequencies.When an acoustic excitation with a frequency close to the flame frequency(or its double frequency clsoe to the flame frequency)is applied,the longitudinal oscillation of the flame will be enhanced,causing a strong flame response,and cause flame instability.
NETL
NSTL
万方数据
维普
