2017 Volume 59 Issue 187 Pages 16-23
This article introduces a research on thermoacoustic instability based on direct numerical simulation (DNS) of a hydrogen-air turbulent swirling premixed flame in a cuboid combustor. To investigate thermoacoustic instability and dynamic modes of a turbulent swirling premixed flame, dynamic mode decomposition (DMD) and spectral analysis are applied to results of the DNS. DMD of pressure field shows that the quarter-wave mode in longitudinal acoustics has the largest energy, while DMD of heat release rate field reveals that the quarter-wave mode in longitudinal acoustics is not a dominant mode in heat release rate field. It has found that oscillation modes caused by large scale vortical motions have large energy not only in pressure field but also in heat release rate field. Dynamic modes of the source term of classical acoustic energy equation are also discussed with the vortical motion and the resonance mode of the combustor.
