Combustion Chamber Acoustics and Its Interaction with LOX/H2- and LOX/CH4-Spray Flames

Abstract

The acoustics of combustion chambers and the interaction of acoustics and combustion is investigated in a model combustor operated with LOX/H2 and LOX/CH4. Acoustic excitations are induced by a siren during hot fire tests and the response of atomization and combustion is recorded with dynamic pressure sensors and high speed OH-imaging is applied. By analyzing the temporal and spatial distribution of the flame response the question is addressed, whether in the experiments the coupling of acoustics to combustion is via pressure or velocity sensitive processes. In the experiments it appeared that the acoustic eigenmodes of the combustor are characteristically deviating from cylinder modes. The results obtained can be explained by a modal analyses of the combustor geometry. These investigations have been extended to study the influence of absorbers and absorber rings on the acoustics of combustion chambers and resonance frequencies predicted by modal analysis and experimental results are presented.