Sound absorption performance of helically perforated porous metamaterials at high temperature

A high-temperature theoretical model is established to investigate the sound absorption performance of helically perforated porous metamaterials (HPPM) at high temperature. Finite element simulations are carried out to validate the theoretical model, and good agreements have been achieved. By perforating three-dimensional helical holes in homogeneous porous material, sound waves can enter the porous material matrix more fully through these extended macroscopic helical perforations, thereby obtaining good low-frequency sound absorption at high temperatures. The results show that with the increase of temperature, the impedance matching between the metamaterial and air becomes better, so as to improve the low-frequency sound absorption ability. Compared to homogeneous porous materials, the average absorption coefficient is greatly improved, especially at higher temperatures. The numerical results of sound pressure and energy dissipation at different temperatures show that high-temperature enhances the pressure diffusion effect at off-peak frequencies, resulting in more energy dissipation in high sound pressure regions. The helically perforated porous metamaterials with large helical diameter and low pitch exhibit better sound absorption performance in the low frequency range. The proposed metamaterial can be used for low-frequency sound absorption at high temperature.