RESUMO
Perforated plates are widely used in many practical burners to attenuate noise emissions. In this study, the acoustic absorption capability of dual perforated plates (DPPs) with different porosities and aperture diameters was evaluated and tested in an impedance tube, and the damping performance of the DPPs located in a liquid fuel combustor inlet section was experimentally studied. The DPPs have an adjustable first cavity and can mitigate the thermoacoustic oscillations within a wide sound absorption bandwidth. The DPPs can absorb 95% of the specified incident sound energy. The combustion results indicated that the installation of DPPs at the inlet section has two effects: sound attenuation and the frequency shift of the combustor. The maximum reduction in dynamic pressure and CH* chemiluminescence intensity inside the chamber were 14 and 19 dB, respectively. When the primary air flow rate deviates from the optimal value, the DPPs can reduce the pressure amplitude in the combustion chamber by almost 80%. In general, this study may promote the application of DPPs under bias flow for the stabilization of spray combustion.
