THE EFFECT OF BIDIRECTIONAL VORTEX COMBUSTOR GEOMETRY ON THE ACOUSTICAL EMISSION OF THE FLAME

The paper reports experimental results on flame visualization and acoustical emission in bidirectional vortex combustors with various lengths for the cylindrical part. The experimental results allowed us to establish the presence of resonant frequencies in the range from 800 Hz to 3500 Hz for bidirectional chambers with a normalized length for the cylindrical part between 2.6d and 6d without combustion reactions. For the first time, we found that the presence of flames in a bidirectional swirling flow dampens resonant frequencies in the range between 500 and 2000 Hz and reduces the amplitude of frequency peaks by 20 dB in the range from 2000 to 3500 Hz. Lean combustion modes have a higher level of acoustic emission across the entire frequency spectrum compared to rich and stoichiometric modes, which is related to the instability of the bidirectional flow and flame location, as confirmed by visualization of the combustion process.