Stabilization effects of perforated plates on the combustion instability in a lean premixed combustor

In the present study, an FDF (Flame Describing Function)-based approach is applied to numerically investigate the attenuation characteristics of a perforated plate. In order to effectively suppress the combustion instability, this study adopts an alternative approach to optimally design a passive damper using a perforated plate. We confirm that the proposed attenuation conditions of a perforated plate ensure quite stable conditions over the entire range of velocity perturbation ratios. Moreover, the present method using Luong model can be applied to all Strouhal number regimes in contrast to a conventional method using the Howe model. Numerical results were also compared with experimental data in terms of the resonant frequency and limit-cycle velocity perturbation ratio. Although slight discrepancies exist, the present FDF-based approach yields an overall agreement with the experimental results. In addition, the numerical results show that perforated plates with smaller holes or thinner plate thicknesses are more effective at stabilizing the oscillation induced by combustion.