شبیه‌سازی عددی عملکرد فراماده جاذب صوت زیرآب دولایه بر پایه فوم متخلخل و لایه تطبیق امپدانس در محدوده فرکانس‌های پایین

This study has numerically simulated the performance of a two-layer underwater sound absorber consisting of porous aluminum foam, impedance matching layer, and metal frame. In this structure, porous aluminum foam is placed inside a metal frame to affect the acoustic behavior in addition to mechanical support. The main goal was to investigate the sound absorption behavior in the low frequency range and evaluate the effect of different materials of the matching layer on the overall performance of the structure. For this purpose, the JCA model was used to describe the acoustic properties of porous aluminum foam and the COMSOL finite element software was used to analyze the dynamic behavior. The results show that the presence of the impedance matching layer improves the conditions for the transfer of sound energy from water to foam and, together with the effects of the metal frame, causes the formation of two main absorption peaks at low and mid frequencies. An investigation of the change in the thickness of the layers showed that the best performance was obtained in the case of 6 mm of porous aluminum foam and 4 mm of matching layer. Also, a comparison of different materials showed that chlorinated polyethylene rubber and styrene butadiene rubber offer the most uniform and stable absorption behavior in the entire range of 0 to 2000 Hz and can be considered as superior options in the design of low-thickness underwater sound absorbers.