ACOUSTIC EXCITATION OF DIFFUSION FLAMES WITH COHERENT STRUCTURE IN A PLANE SHEAR-LAYER - (APPLICATION OF ACTIVE COMBUSTION CONTROL TO 2-DIMENSIONAL PHASE-LOCKED AVERAGING MEASUREMENTS)

In previous work, it was shown that acoustic excitation of a plane dif fusion 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 obtai n graphical 2 D contour maps of the instantaneous profiles of temperat ure and CH emission. Both maps of eight consecutive phases indicated c learly not only the periodic behavior of the organized eddy flame, but also the gas dynamic properties peculiar to those flames with coheren t structure. The profiles of local contribution of the sound field to the combustion process were also examined by calculating the 2 D distr ibution of the local Rayleigh index. The latter showed that the organi zed eddy flames are highly sensitive to sound, and play an important r ole in sound-flame interaction.