Articles techniques et présentations

It is well known that high noise levels can result in psychological and physiological discomforts. Mufflers are used for reducing exhaust noise from automotive engines. Simple expansion chamber is a well-known design of a muffler. However, it fails to perform at frequencies that coincide with half wave resonances of chamber length. Double expansion chamber is one method to improve noise reduction of the muffler, but it takes more space. Recently, Acoustic black hole (ABH) has been used to control vibrations in structures, which is characterized by its power-law profile. ABH can also be applied to sound propagation in ducts. This work presents numerical simulation using COMSOL Multiphysics^® simulation software to study the acoustic performance of the double expansion chamber incorporating ABH. The modified double expansion chamber muffler can eliminate the zero transmission loss corresponding to resonance frequencies and decrease the volume of the chamber. Excellent results are obtained using the Acoustics Module of COMSOL Multiphysics^®. The potential of using ABH in design mufflers is also discussed.