On the Noise of Diffusion Flames

Abstract

The mechanism of the generation and characteristics of the noise associated with combustion are studied. It is shown that the dominant factors on the generation of the combustion noise are the velocity turbulences and the entropy turbulences, acting as equialent acoustic dipole and source respectively. Especially, concerning the diffusion flame of premixed gases, the noise in the laminar flame is mostly due to the entropy fluctuation (source-like characteristics) and that in the turbulent flame is mainly attributed to the velocity fluctuation (dipole-like characteristics). The noise intensities are proportional to U² and U⁴ respectively and to the cubic power of the diameter of the nozzle.