USING THE TRANSFER MATRIX METHOD ANALYZING MUFFLER PERFORMANCE

Mechanical Engineering

Internal combustion engine is considered as a major source of noise pollution. And these engines are used for various purposes such as, in power plants, automobiles, locomotives, and in various manufacturing machineries. Engine created noise pollution becomes a vital concern when used in residential areas or areas where noise creates hazard. Generally, noise level of more than 80 dB is injurious for human being. Exhaust noise and the noise produced due to friction of various parts of the engine are the main sources of noise in an engine. The exhaust noise is the most dominant one and to reduce this noise, various kinds of mufflers are generally used. The construction and the working procedure of mufflers usually affects the level of exhausts noise reduction. Engine makers have been making mufflers for more than 100 years. As the name suggests, muffler serves the primary purpose as to reduce or muffle the noise emitted by the internal combustion engine. Technology for muffler has not changed very much over the past 100 years. The exhaust is passed through a series of chambers in reactive type mufflers or straight through a perforated pipe wrapped with sound damping material in an absorptive type muffler. Both types are having strengths and weaknesses. The reactive type muffler is generally restrictive and prevents even the good engine sounds from coming through, but it does a good job of reducing noise. On the other hand, most absorptive type mufflers are less restrictive, but allow too much engine noise to come through. Despite of the packing material, absorptive type mufflers tend to get noisier with time.

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