模型燃烧室中值班火焰稳定器的燃烧不稳定性研究

The experimental method was used to study combustion instability of the pilot flame. The flame structure，pressure pulsation signal and heat release pulsation signal under different equivalence ratios were ob⁃ tained. Through Fourier analysis of the pulsation signals，the frequency and amplitude of pulsation signals were obtained. The results show that the flame morphology changed and a transition from three order mode（164Hz）to two order mode（109Hz）occurred as the equivalence ratio increased in the combustion chamber. After analysing the flame average structure，the periodic change of flame transient structure and the result of proper orthogonal decomposition（POD），it was found that the coupling between the vortex shedding frequency and a certain order acoustic mode of the combustion chamber is the mechanism maintaining combustion instability. The strength of the coupling and the scale of the vortex shedding determine the amplitude of the thermoacoustic oscillation. Changing of the heat release center location caused by the changing of flame morphology is the mechanism caus⁃ ing modal transition.