Combustion Noise from Plane Diffusion Flames with Organized Structure : Correlations between Organized Structure and Combustion Noise

Abstract

The combustion noise generated from turbulent diffusion flames with organized structure is investigated to obtain clear figures and solid explanations about the interdependency between flame structure and sound characteristics. In this paper, an experimental study is made on the flames established in the plane shear layers of three types having different flow and turbulence conditions. Our main interests are devoted to a confirmation of the dependency of the acoustic pressure perturbation on the fluctuations of ion current and temperature within the flames. The results show that, not only the fluctuations of ion current and temperature, but also the sound pressure fluctuation gives some clear regularity in the frequency spectra and possesses relatively strong coherency with each other in the flames with organized structure, while little regularity is observed in the flame without any organized structure. It is concluded that the acoustic pressure perturbation is rather dominated by the organized structure in the flame.