Sound attenuation in dissipative expansion chambers

A one-dimensional analytic approach, three-dimensional boundary element method (BEM), and experimental methods were used to study the acoustic attenuation for both a single-pass dissipative expansion chamber and a Helmholtz resonator. An analytical approach was proposed based on the solution of eigenequation for a circular dissipative expansion chamber. The acoustic pressure and particle velocity across the silencer discontinuities were matched by imposing the continuities of the velocity/pressure integral over discrete zones at the expansion/contraction.