Enhancing grazing incidence sound absorption in three-dimensional printed triply periodic minimal surfaces through geometric asymmetry

Triply periodic minimal surfaces (TPMS) offer promising absorption performance due to their tunable geometry. Previous findings under normal incidence conditions show that introducing geometric asymmetry can enhance sound absorption without increasing overall density. This study investigates whether those improvements hold under grazing incidence conditions with and without flow, which are more representative of practical flow environments. TPMS samples are fabricated using fused deposition modeling, and their acoustic response is measured in the Grazing Flow Impedance Tube (GFIT) at NASA Langley Research Center. Results confirm that symmetry-breaking improves low frequency absorption under grazing incidence, mirroring outcomes observed at normal incidence. These findings underscore the versatility of TPMS-based approaches for advanced noise mitigation while maintaining minimal mass. Overall, harnessing geometric asymmetry offers a powerful means to optimize performance across diverse incidence angles, laying the groundwork for lightweight, high-performance acoustic liners suitable for aerospace, automotive, and industrial applications.