Idealized silencers consisting of cavity-backed clamped porous elastic plates parallel to the direction of flow can result in low frequency attenuation of noise in the duct. The insertion loss of perforated and non-perforated poroelastic plate silencers have been measured with and without mean air flow. Peak IL when the plate is not perforated has a value of 4.1 dB at 1 kHz without air flow. With perforations the peak IL is 3.2 dB at 630 Hz. In the presence of mean air flow, without self-noise, peak IL have values of 17 dB at 250 Hz and 7 dB at 400 Hz for the air flow speeds of 37.65 m/s and 5.5 m/s respectively. Peak IL of perforated and non perforated porous plate has values of 11 dB and 11.5 dB at 160 Hz with noise and air flow at speed of 37.65 m/s. The displacements of a perforated and non-perforated porous elastic plates separated from duct wall by an air cavity in the duct have been measured and compared with those of the duct wall.
|Title of host publication||Spring Conference of the Institute of Acoustics, April 10 - 11, 2008, Reading UK|
|Publication status||Published - 1 Apr 2008|