Role of Coherent Structures in Turbulent Premixed Flame Acoustics

Spectral proper orthogonal decomposition (SPOD) is applied to direct numerical simulation datasets of a lean and a stoichiometric methane–air turbulent premixed jet flame. SPOD is used to extract the coherent structures that correlate with the radiated sound by using an inner product based on a linearized disturbance energy. Two types of structures are prominent in the data. The first type arises in the jet’s shear layer and is linked to the...