Low frequency attenuation of acoustic waves using sound-soft scatterers

Autor: Alexander Dell, Anton Krynkin, Kirill Horoshenkov, Gavin Sailor
Rok vydání: 2023
Zdroj: INTER-NOISE and NOISE-CON Congress and Conference Proceedings. 265:4941-4949
ISSN: 0736-2935
DOI: 10.3397/in_2022_0714
Popis: The attenuation of acoustic waves by silencers is typically achieved through the employment of rigidly backed cavities, connected to a main waveguide by a perforated panel. This invokes a resonant response at frequencies determined by the dimensions of the perforation and the rigidly backed cavity. A limiting factor in this approach is that to achieve low frequency attenuation, either large cavity depths are required, which is often impractical, or narrow neck regions need to be used, where performance is limited due to the viscothermal losses. Within this paper, a non-rigidly backed perforated pipe is presented where the pressure release condition at each perforation creates an acoustic sound-soft boundary condition. By the introduction of sound-soft boundary conditions, a low frequency band gap is created as the first order mode is shifted to a non-zero value, the frequency of which is determined by the dimensions and separation of the perforations. Experimental results displaying this band gap are presented along with numerical models verifying the phenomenon and an ideal analytical model based upon the transfer matrix method.
Databáze: OpenAIRE