چكيده به لاتين
Following the path of the exhaust system of combustion gases (the exhaust system), after the headers (smoke manifold), the muffler is placed. Muffler, or in other words, the suppressor tank, plays a role in controlling the output sound of the exhaust. The necessity of using a muffler and need to it will be understandable when considering the type of combustion engine. Changes to the muffler geometry can improve the level of sound transmission loss. The level of sound transmission loss mufflers with optimum sizes compared to the level of that of mufflers with original size, has a more bandwidth and 20% higher transmission loss level. Consequently, the use of Taguchi method in optimization of geometric parameters can be considered as a suitable solution and finally using glass wool absorbent material, the level of sound transmission loss can be doubled and a wide frequency bandwidth can be created. In this study, the level of sound transmission loss in embedded car mufflers is investigated. To calculate the level of sound transmission loss there are transmission matrix methods, three-point method, quadrupole method, Finite Element Method (FEM) and Boundary Element Method (BEM). In this study, due to the high accuracy and speed of solution, boundary element method is used. Exhaust storages including internal geometry with simple expansion chamber, perforated tubes, baffle, microporous panel and absorbent mufflers with curved tubes have been modeled using the CATIA software and the sound transmission loss in them has been calculated by COMSOL software. After verifying the results, the geometrical parameters of a more complex structure muffler containing geometrical factors affecting the level of sound transmission loss are optimized by the Taguchi algorithm.
