Including Flow–Acoustic Interactions in the Helmholtz Computations of Industrial Combustors

Abstract

A methodology to include flow–acoustic interactions in a Helmholtz solver is proposed and used to quantify their impact on the thermoacoustic modes of a real industrial combustor. This methodology takes advantage of the compactness of flow–acoustic interactions, modeling the regions of interest by matrices included in the Helmholtz computation thanks to a dedicated boundary condition. The one-dimensional formulation introduced in Ni et al. (“Accounting for Acoustic Damping in a Helmholtz Solver,” AIAA Journal, Vol. 55, No. 4, 2017, pp. 1205–1220) is extended to three-dimensional configurations so that the dissipation of dilution holes, swirlers, and perforated plates can be accounted for. The potential of the method is illustrated by performing the thermoacoustic analysis of an annular combustor from SAFRAN. The Helmholtz solution corresponding to an azimuthal mode is analyzed and shows that flow–acoustic interactions dissipate an important part of the acoustic energy but also limit the amplification created by the flame.