A Time-Domain Computational Simulation of Acoustic Silencers

A one-dimensional finite difference numerical method is applied for the simulation of sound attenuation in reactive silencers placed in an impedance tube configuration. This time-domain approach solves the nonlinear fundamental balance equations of mass, momentum and energy, and the equation of state. The temporal solution is first converted to the frequency domain by the Fast Fourier Transform, which is then processed by the two-microphone technique to yield transmission loss. Results are presented for the attenuation of acoustic disturbances in four basic configurations including the expansion chamber, Helmholtz resonator, quarter-wave resonator and Herschel-Quincke tube. A comparison to available experimental data and linearized acoustic theory shows excellent agreement for silencers with both anechoic and echoic terminations.