Broadband ventilated reactive muffler based on topologically optimized metasurface

In this study, a ventilated acoustic metamaterial is developed to address the inherent trade-off between airflow capability and broadband noise attenuation in engineering applications. A genetic algorithm-based topology optimization framework is employed to design a compact structure consisting of a central ventilation duct surrounded by optimized acoustic cavities. By tailoring the optimization objectives, effective broadband noise attenuation is achieved while maintaining practical ventilation open areas of 25%, and robust performance is preserved even at ventilation levels up to 50%. Numerical simulations under low-velocity airflow conditions are conducted to evaluate the influence of airflow on the acoustic performance. To extend the effective bandwidth of noise attenuation, two topology-optimized configurations targeting complementary frequency ranges are proposed, resulting in a transmission loss exceeding 10 dB over 632–2260 Hz, with a peak value of 46.4 dB. To assess structural robustness and practical applicability, simplified equivalent models are established and validated through both numerical and experimental investigations. Experimental measurements of additively manufactured prototypes show good agreement with the numerical predictions, confirming the effectiveness of the proposed design strategy.