Optimal assessment of wool lining inside multi-tube mufflers with a rectangular section using the boundary element method and the genetic algorithm

Abstract

Recently, research on new mufflers equipped with connected curved tubes using phase cancellation techniques has been addressed in the industrial field. On the basis of the transfer matrix method and the stiffness matrix method, researchers have explored noise reduction effects within a constrained space. However, the attenuation bands are too narrow and the overall acoustical performance in dealing with broadband noise is thus insufficient. Therefore, in order to broaden the spectrum of the acoustical performance curves at various targeted tones (250, 500, and 900 Hz), a wool optimally lined within the ducts of HQ mufflers is proposed. In this paper, five kinds of HQ mufflers with rectangular sections (muffler A: a double-connected curved tube muffler; muffler B: a double-connected abrupt tube muffler; muffler C: a one-sided triple-connected curved tube muffler; muffler D: a two-sided tripleconnected curved tube muffler; muffler E: a one-sided triple-connected abrupt tube muffler) within a fixed length are assessed. In order to facilitate the assessment of optimal mufflers, a boundary element model (BEM) is adopted as the mathematical objective function. To assess the optimal mufflers, a genetic algorithm (GA) is linked with the BEM. Before the GA operation can be carried out, the accuracy of the mathematical models must be checked using the experimental data. Optimal results reveal that the maximum value of the sound transmission loss (STL) can be optimally improved at the targeted frequencies. Consequently, the optimum algorithm proposed in this study provides an efficient way to find a better silencer for industry.