Research on new techniques of side-inlet/outlet mufflers equipped with internal
non-perforated intruding tubes has been discussed in recent literature; however, the
research work of multi-chamber sideinlet/outlet mufflers in conjunction with cross-flow
tubes and open-ended perforated intruding tubes which may efficiently increase the
acoustical performance is rare. Therefore, the main purpose of this paper is not only to
analyze the sound transmission loss (STL) of three kinds of
side-inlet/outlet mufflers (a three-chamber muffler with cross-flow tubes, a five-chamber
muffler with cross-flow tubes and a nonperforated tube, and a five-chamber muffler with
cross-flow tubes and a perforated tube) but also to optimize their best design shape
within a limited space.
In this paper, both the generalized decoupling technique and plane wave theory in solving
the coupled acoustical problem are used. A four-pole system matrix in evaluating the
acoustic performance is also deduced in conjunction with a simulated algorithm
(SA). A numerical case in finding the optimal STL of
mufflers, which is constrained within a basement with a side-inlet/outlet, at targeted
tones has been introduced. Before the optimization is carried out, an accuracy check of
the mathematical model is performed. Results reveal that the maximal STL
is precisely located at the desired target tone. Moreover, it has been seen that mufflers
with more chambers will increase the acoustic performance for both pure tone and broadband
noise. Additionally, the acoustical performance of mufflers conjugated with perforated
intruding tubes is superior to those equipped with non-perforated tubes.
Consequently, the approach used for seeking the optimal design of the STL
proposed in this study is indeed easy and quite effective.