Duct Anechoicity Based on the Acoustic Black Hole Principle

As a novel passive control method, the acoustic black hole (ABH) structure demonstrates achieve energy aggregation efficiently and has the characteristics of lightweight and wide-band noise reduction. This study applies ABH theory to aircraft ducts by incorporating an additional ABH structure into the inner wall design. The spiral structure is specifically engineered to increase the characteristic length of the black hole and lower the cutoff frequency. To validate the effectiveness of this ABH structural design, finite element analysis was conducted to investigate structural frequency response, acoustic energy concentration characteristics, as well as damping and energy dissipation effects. Simulation results indicate significant energy accumulation on the inner wall with ABH structure in frequencies above 800Hz. Additionally, through acoustic-structure coupling analysis, far-field acoustic radiation characteristics were determined for this structural design followed by a comprehensive summary analysis.