On the Noise of Diffusion Flames

Abstract

The mechanism of the generation and the 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 equivalent acoustic dipoles and monopoles, respectively. Especially, concerning the diffusion flame of rich-premixed gaseous fuel, the noise in the laminar flame is mostly due to the entropy turbulences and of monopole-like characteristic, and that in the turbulent flame is mainly attributed to the velocity turbulence and of dipole-like characteristic. The noise intensities are proportional to the second and the fourth power of the mean flow velocity, respectively, and to the cubic power of the diameter of the nozzle.