چكيده به لاتين
Sound transmission loss (TL) is an important parameter to evaluate the performance of mufflers, which is an essential device in vehicles. Increasing the sound transmission loss is desirable, and as it increases, the muffler becomes more efficient. Backpressure is another parameter that must be reduced to apply less pressure to the engine, followed by improved engine efficiency. This dissertation aims to increase the sound transmission loss in the muffler by considering the backpressure, which should not be increased. TL is calculated by solving the Helmholtz equations, and the k-epsilon turbulent flow model is used to simulate the engine exhaust gas and find the backpressure. The analysis of sound transmission loss by the transfer matrix method (TMM) assumes the plane wave and finite elements using the COMSOL software without taking the plane wave. The back pressure is also modeled with Ansys Fluent. To optimize the length of muffler tubes, the Nelder-Mead algorithm is used and compared with the one-half and one-fourth extended tube model. Backpressure is not considered in most studies. TL has almost doubled, and the valleys in the TL diagrams have been corrected. After optimization, the backpressure remained virtually constant, which is positive in muffler's design and optimization.
