Acoustic attenuation performance analysis of multi-chamber reactive silencers

The multi-chamber reactive silencers are widely used to reduce engine exhaust noise as well as blower intake and discharge noise. Davis et al. [1] developed a one-dimensional analytical approach, which assumes plane wave propagation in the axial direction in silencers, to predict the acoustic attenuation performance of double expansion chamber reactive silencers, and compared the predictions with experimental results. They investigated the effect of the length of interconnecting tube on the acoustic attenuation performance of the silences with chambers of equal lengths. The transfer matrix approach based on the one-dimensional plane wave theory is described in detail by Munjal [2] for several acoustic elements and silencer configurations. The plane wave theory, however, excludes the effect of multi-dimensional waves inside the silencers. Thus, while yielding reasonable predictions at lower frequencies, the simplistic approach is expected to deviate from experimental results at higher frequencies. Above the plane wave cut-off frequency, one-dimensional plane wave approach is not applicable to predict the acoustic attenuation performance of silencers. For the large size silencers, the plane wave cut-off frequency is lower and high-frequency acoustic attenuation performance prediction is still desired for the purpose of noise control. Therefore, a multi-dimensional approach is required for the accurate prediction of acoustic attenuation performance of silencers. The boundary element method (BEM) is suitable to predict the acoustic attenuation performance of reactive silencers with any