Acoustic excitation of diffusion flames with coherent structure in a plane shear layer - (Application of active combustion control to two-dimensional phase-locked averaging measurements)

In previous work, it was shown that acoustic excitation of a plane diffusion flame enhanced the periodicity and intensity of organized-eddy-controlled combustion. The main objective in this work was to examine phase characteristics of the excited eddy flames with high periodicity. A computer-aided phase-locked averaging method was employed to obtain graphical 2 D contour maps of the instantaneous profiles of temperature and CH emission. Both maps of eight consecutive phases indicated clearly not only the periodic behavior of the organized eddy flame, but also the gas dynamic properties peculiar to those flames with coherent structure. The profiles of local contribution of the sound field to the combustion process were also examined by calculating the 2 D distribution of the local Rayleigh index. The latter showed that the organized eddy flames are highly sensitive to sound, and play an important role in sound-flame interaction.