SHAPE OPTIMIZATION OF COMPLEX MULTI-CHAMBER MUFFLER

Abstract

A complex multi-chamber muffler is the most common noise control filter used for automotive exhaust systems. It is important when searching for an efficient acoustical mechanism to have an optimally shaped muffler designed especially for the constrained space found in today's vehicles. The research work of optimally shaped of multi-chamber perforated ducts is rarely addressed; so this paper will not only analyze the sound transmission loss (TL) of complex multi-chamber perforated muffler but also will analyze the optimal design shape within a limited space.

The four-pole system matrix that is used in evaluating acoustic performance is derived by using the decoupled numerical method. Moreover, a simulated annealing (SA) algorithm, a robust scheme in searching for the global optimum by imitating the softening process of metal, has been adopted during shape optimization.

To assure SA's correctness, the TL maximization of multi-chamber perforated mufflers at a targeted frequency of 1000 Hz is tested first. The result of the optimized muffler is compared with the measured results at room temperature. Furthermore, a numerical case in dealing with a broadband noise emitted from an I.C. Engine by using complex multi-chamber perforated mufflers has been introduced and fully discussed.