A study of the application of global optimization for the arrangement of absorbing materials in multi-layered absorptive fluid silencer

In naval ships and submarines, silencers are installed to reduce pipe flow noise. Due to limited space, the size of the silencers is restricted, requiring them to have excellent acoustic performance. In this study, to improve the acoustic performance of a multi-layer absorptive fluid silencer, the physical properties of the absorbing material, mesh, and design parameters were reviewed in detail compared to previous studies. A global optimization algorithm was introduced to find the optimal layering of the absorbing materials. The acoustic performance of the silencer was evaluated through transmission loss. To calculate the transmission loss, a finite element method-based numerical analysis program (COMSOL) was used along with genetic algorithm and simulated annealing for global optimization. The absorbing material used was polyurethane, a porous elastic material, and five practically applicable absorbing materials were selected. The placement and thickness of these materials in each layer were optimized, and the reliability of the global optimization techniques was verified through comparison with solutions from a brute force algorithm. Additionally, an application method was proposed to find the optimal solution in a short time, even for silencers with more than ten layers.