The main idea in this entry was to introduce a methodology and concludingly an optimized geometry for a commercial reactive muffler for noise reduction in auto applications. Due to a large number of variables (geometrical and mode) involving in the topology optimization of the common commercial mufflers, the need for a novel methodology with the ability to cover all the input variables is a must.

Here, first, a suitable mathematical-acoustic model was developed for a three-pass perforated element with an end resonator chamber (TPER). Then, using this model, a new evolutionary, multi-objective, multivariate epsilon-genetics algorithm (𝜖-MOGA), the acoustic performance of the desired geometry was optimized separately. This optimization included the definition of independent variables and design objectives, each within a predefined range. Objectives were minimization of muffler volume, maximization of transmission loss frequency response, and back-pressure. Using the optimized TPER muffler, the CAA simulation results showed at frequencies below 3000 Hz, had reduced the SPL between zero and 30 dB, and backpressure reduced from 10 kPa to 235 Pa. While the volume of the muffler was reduced four times.