Acoustic behaviour analysis and optimal design of a multi-chamber reactive muffler

A two-dimensional analytical approach is developed to study the acoustic behaviour of a multi-chamber reactive muffler. The value of the transmission loss is obtained by matching the acoustic pressure and the particle velocity across the interfaces between different domains in the muffler. The analytical approach is validated by experimental results. Unlike the transfer matrix method, with this approach the acoustic behaviours can be studied above the first cut-off frequency of the muffler. Next, the effects of several structural parameters on the transmission loss value are invetigated, including the radii of the baffle holes, the inlet and the outlet, as well as the lengths and the radii of the expansion chambers. The variations in these parameters lead to quite large changes in the value of the transmission loss of the multi-chamber reactive muffler. Then, these parameters are chosen as the variables for the optimal design of the muffler, where the objective is the average transmission loss value between 1000 Hz and 3000 Hz. The results show that the objective value increases from 23.3 dB to 54.9 dB during optimization. The analytical approach in this paper can be used for analysis and optimization of the multi-chamber reactive muffler to reduce the noise effectively and efficiently in various applications.