Evaluation of combustion oscillation using sound pressure amplification from premixed flames

In this study an evaluation way of combustion oscillation is presented with emphasis given to both amplification of the pressure fluctuation by premixed flames and the attenuation at burner. Amplification of pressure fluctuation is measured by a burner system that the fuel-air mixture is forced to excite by a loudspeaker. The results are compared with the attenuation of pressure fluctuation at the burner. It is found that combustion oscillation is not observed when the attenuation exceeds the amplification, although Rayleigh's criterion shows a conditionally positive result. It shows that present work would be a practical way to suppress combustion oscillations in the stage of designing gas appliances.