Duct Metamaterial Muffler with Composite Acoustic Porous Media: Acoustic Optimization via Periodic Arrangement, Particle Swarm Optimization and Experimental Validation

The study proposes a duct muffler design that combines structural resonance from a perforated tortuous channel with sound damping from an externally wrapped porous layer. The authors derive analytical models for acoustic impedance and transmission loss for the composite structure. They then use finite element simulations to check the model accuracy and run parametric studies to see how porous material type, thickness, and width affect performance. The results indicate polyester fiber performs best at 30 mm thickness and 5 mm width, and periodic arrangement patterns can shift peak attenuation and broaden bandwidth. To make the design practical for duct conditions, the authors build a single-layer multi-cell array and clarify its modal excitation mechanism. Using Particle Swarm Optimization (PSO), they improve average transmission loss, and they fabricate 3D-printed physical samples for four-sensor impedance tube experiments that agree with theory and simulation.