Numerical Analysis on Improving Transmission Loss of Reactive Muffler using Various Sound Absorptive Materials

Abstract

Finite element analysis approach is used to determine the transmission loss for an optimized geometry of reactive multi-chamber muffler. The pressure acoustics theory is involved in the present problem and it examines the wave nature of sound and also the intensity with which it propagates. COMSOL Multiphysics software was used for modelling and analysis. The acoustics module with parallel study in frequency domain was utilized to study the flow and acoustic behaviour of the reactive muffler. Various absorptive liner materials were considered for the muffler and the transmission losses were compared. In addition to the above, the thickness of liner and inlet pressure were varied in order to have profound work for discussion. The validation of predicted transmission loss is in good agreement with the referred experimental data. The result for different types of absorptive liner materials was tracked in comparison with the muffler without liner. The average transmission loss was found to be increased by 8% with the introduction of absorptive liner with 10mm thickness. Finally, the calculated sound pressure level with total acoustic pressure field and streamlines intensity provide insight of the physics involved.