Sound generation by ducted flames

The sound field established by a v-shaped flame confined in a rectangular duct is investigated both theoretically and experimentally. A theoretical model is developed to predict pressure spectra caused by the unsteady heat release from the flame. Comparisons between the theoretical and experimentally measured spectra confirm the validity of the model and are also reported. It is also found that changes in the flowfield in the flame zone can significantly modify combustion rates. These modifications, in turn, affect the generated sound field and are important in determining the pressure levels in the duct. The results of this investigation are applicable to combustion noise and instability studies in a variety of burner and propulsion system configurations. 15 references.