Optimization and experimental validation of perforated plate acoustic liners for enhanced noise reduction in acoustic waveguides

Combustion instabilities caused by thermoacoustic couplings are widely encountered in various combustion systems. As a passive control method, perforated plate acoustic liner structures exhibit excellent performance in suppressing combustion instability. In this study, a novel axial segmented acoustic liner is proposed to address the noise reduction problem at multiple frequency points within the combustion chamber. Using a high-order mode acoustic waveguide test rig and the transfer element method, the acoustic attenuation of test specimens under different parameters was evaluated. The study focused on analyzing the transmission loss and the sensitivity for cavity length, perforation ratio, and cavity depth. The study results showed that the structural parameters, including smaller apertures, thinner plates, or higher perforation ratios, enhance peak transfer loss (TL) and broadband noise reduction, though increased perforation raises resonance frequency. Cavity dimensions critically influence peak distribution: short cavities exhibit a single length-independent resonance, while elongated cavities generate multiple absorption peaks and dome-shaped TL curves, with deeper cavities amplifying resonance complexity. Furthermore, COMSOL simulation was conducted to confirm that the axial segmented acoustic liner design can achieve more comprehensive noise reduction than a single-segment liner.