Sound sources in premixed flames

Abstract

This paper presents a technical review of our understanding of the mechanism of sound generation by premixed flames. Examples from direct numerical simulation (DNS) studies undertaken at the University of Melbourne are provided. Furthermore, the implications of the findings for developing accurate models that can predict combustion-generated sound are discussed. This paper demonstrates that flame-flame interactions referred to as ‘flame annihilation’ are significant sources of sound in premixed flames. These localised events feature several unique characteristics that cannot be explained with existing turbulent flame theories. It is shown that flame acceleration during annihilation has a significant contribution to the radiated sound. Therefore, in the context of modelling, it is essential to predict the flame displacement speed during annihilation as accurately as possible. Analysis of the DNS data shows promising avenues to meet this requirement.