Resonator-based broadband noise absorber to control combustion instability

Combustion instabilities are one of the primary concerns in a combustion system. Acoustic resonators are used as passive dampers to suppress these instabilities. In the present work, we describe the design, fabrication, and testing of an ultrathin broadband acoustic absorber to dampen the instabilities. The design consists of a series-parallel combination of quarter-wave resonators wrapped like a coiled thin shell around the outer wall of the combustor. The proposed structure is optimized through numerical simulation to improve its performance across the 100--200-Hz frequency band. Numerical and analytical investigations are conducted to examine the impact of turbulent flow with a low Mach number. Experiments are performed for the no-flow, no-heat-source case to validate the analytical and numerical results.