Denia Guzmán F., Selamet A., Martínez Bordes M., Torregrosa Huguet A.

An analytical model is presented for the acoustic attenuation performance analysis of circular hybrid mufflers consisting of two short lateral chambers and a central dissipative cavity filled with sound absorbing material. The two-dimensional axisymmetric analytical approach developed to evaluate the muffler performance is based on an eigenequation that accounts for the wave propagation through the absorbing material and the perforations. Once the solution of the transversal eigenproblem is computed, the muffler transmission loss is calculated by matching the acoustic pressure and normal velocity across each geometrical discontinuity. The validation of the proposed procedure is carried out by means of the finite element method and some experimental measurements. The sound attenuation is examined and compared considering the effect of the internal geometry of the muffler, the properties of the sound absorbing material and the porosity of the perforated central pipe. It is shown that the combination of the radial resonances in the short lateral chambers and the dissipative effects associated with the central cavity can lead to an improved acoustic performance in a wide frequency range.