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Abstract

It has been noted that the application of high performance, compact mufflers is the future for modern factories where place is at a premium. However, as research on mufflers equipped with extended tubes has been exhausted, and frankly at the juncture, shown to be inadequate (unsuitable), attention has turned to mufflers conjugated with perforated intruding tubes which can dramatically increase acoustical performance. Therefore, the focus of this paper is not only to analyze the sound transmission loss (STL) of a one-chamber open-ended perforated muffler but also to optimize the best design shape within a limited space. In this paper, the four-pole system matrix for evaluating the acoustic performance ― sound transmission loss (STL) ― is derived by using a decoupled numerical method. Additionally, a simulated annealing (SA), a robust scheme used to search for the global optimum by imitating the metal’s heating process, has been used during the optimization process. Before dealing with a broadband noise, the STL’s maximization with respect to a one-tone noise is introduced for a reliability check on the SA method. Also, an accuracy check on the mathematical model is performed. To appreciate the acoustical ability of the new mufflers, traditional mufflers, including a simple expansion muffler as well as a non-perforated intruding-tube muffler, have been assessed. Results reveal that the maximal STL is precisely located at the desired targeted tone. In addition, the acoustical performance of mufflers conjugated with perforated intruding tubes is found to be superior to the traditional mufflers. Consequently, the approach used for the optimal design of the noise elimination proposed in this study is quite effective.

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