Investigation on the Effects of Acoustic Liner Variation and Geometry Discontinuities on the Acoustic Performance of Lined Ducts

Noise reduction inside waveguide systems has gained momentum owing to a great interest in it. To attenuate the sound broad frequency range, this study aims compare effects of two acoustic liners, perforated plate backed by an air cavity (PP-Air cavity), or porous material (PP-PM), on behaviour lined ducts using numerical model compute multimodal scattering matrix. From matrix, reflection and transmission coefficients are computed therefore power attenuation is deduced. Moreover, geometry with without changes section investigated. The results obtained for five configurations, including cases narrowing widening duct portion sudden progressive discontinuities. Accordingly, as well show relative influence liners each type configuration.