High-temperature acoustic absorption for circular-ring slit type perforated porous metamaterial

A novel high temperature sound absorption metamaterial based on porous substrated is proposed in this paper, which demonstrates high sound absorption performance in low frequency ranges. Circular-ring slit perforated porous metamaterial (CRPPM) is obtained by perforation of circular-ring slits on the basis of pure ceramic materials. Here, CRPPM can be regarded as a composite structure of cylindrical perforated porous material (CPPM) and cylindrical porous matrix (CPM). A theoretical model of high temperature double porosity is established to describe the acoustic characteristics of multi-physical fields, and the accuracy is verified by finite element simulation. The underlying acoustic energy absorption mechanisms are explored through analyzing the distribution of sound pressure field, particle vibration velocity and energy dissipation density. The results reveal that low-frequency long-wavelength acoustic waves are dissipated by entering the circular-ring slit perforations, and high acoustic intensity flow and energy density appear in the interface of the perforations. Compared with the equivalent cylindrical perforation material (ECPM) and CPPM, CRPPM has excellent low-frequency sound absorption properties. Then the influences of height and static flow resistance on sound absorption are analyzed. As the sample height decreases, the peak frequency of the sound absorption curve shifts slightly to higher frequency, and the half-absorption bandwidth gets broaden at different temperatures. With the increase of static flow resistance, the sound absorption capability in low frequency ranges tends to be stable, while the half-absorption bandwidth gradually narrows. The novel high-temperature porous metamaterials proposed in this paper can effectively improve the acoustic absorption performance at low frequencies in high-temperature environments. ● A novel absorptive metamaterial is proposed for high temperature and low frequency. ● An acoustic theoretical model is proposed to predict the sound absorption performance at high temperature. ● The FE method is established to verify the accuracy of the theory, and has good consistency between them. ● The sound absorption peak frequencies are 295 Hz, 372 Hz, 410 Hz and 485 Hz at 20℃, 200℃, 300℃ and 500℃, respectively. ● The proposed metamaterial is suitable for low frequency and high temperature applications.