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中国物理学会期刊

二维声学黑洞结构高灵敏度水听器

CSTR: 32037.14.aps.74.20250741

High-sensitivity hydrophone with two-dimensional acoustic black hole structure

CSTR: 32037.14.aps.74.20250741
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  • 针对目前水下微弱信号探测对水听器高灵敏度的需求, 提出一种声学黑洞结构形式的高灵敏度水听器. 从几何声学出发, 将声学黑洞中弯曲波汇聚特性类比为水声学中声线弯曲, 提出一种波聚集特性简化理论. 基于该特性设计了一种二维声学黑洞水听器, 通过在弯曲式水听器中引入二维声学黑洞结构, 实现振动聚集, 进而提升水听器的高灵敏度性能. 通过结构控制变量, 对比分析4种厚度形式板, 验证了声学黑洞板在1.7—5.8 kHz频段内提高水听器接收灵敏度的显著优势. 分析了声学黑洞结构水听器接收灵敏度起伏较大的原因, 并进一步设计了声学黑洞与单端开口Helmholtz液腔耦合水听器, 将前两阶声学黑洞弯曲振动模态与液腔模态耦合实现宽带接收特性. 制作了两种水听器样机并在消声水池中进行测试. 结果表明, 二维声学黑洞水听器通过弯曲振动聚集效应可有效提高水听器接收灵敏度, 并与液腔结构通过多模态耦合形成宽带, 在2.6—5.3 kHz频段内灵敏度最高可达–169 dB, 起伏控制在8 dB以内.

     

    Acoustic black hole (ABH) structures are renowned for their unique wave-focusing ability and have been widely utilized in the fields of acoustics and vibration. Based on this property, a novel high-sensitivity hydrophone design incorporating a two-dimensional (2D) ABH structure is proposed in this work. According to the principles of geometrical acoustics, the wave-converging behavior of bending waves in ABH structures is compared to the bending of acoustic ray in underwater acoustics. A simplified theoretical model describing the relationship between the bending wave trajectory and the wave speed gradient in polar coordinates is established for two-dimensional (2D) ABH configurations and verified through numerical simulations. Based on this mechanism, a 2D ABH hydrophone is developed by integrating the ABH structure into bending-plate hydrophone, enabling vibration energy concentration and significantly enhancing sensitivity. The comparative studies of hydrophones using uniform-thickness plates and linearly tapered thickness plates as receiving surfaces confirm the superior performance of the ABH hydrophone in a frequency range of 1.7–5.8 kHz. To address the significant undulations observed in the sensitivity response, which is attributed to vibration superposition, a liquid cavity of specific length is introduced. This leads to the development of an ABH-Helmholtz-coupled hydrophone (ABHH hydrophone), wherein the first two bending modes of the ABH structure are coupled with the resonant modes of a single-ended open liquid cavity, resulting in broadband reception capability. The prototypes of both hydrophone designs are fabricated and experimentally tested in an anechoic water tank. The results show that both devices achieve peak receiving sensitivities exceeding –169 dB. Notably, the ABHH hydrophone maintains sensitivity fluctuations within 8 dB in a frequency band of 2.6–5.3 kHz. This study confirms that 2D ABH structures can effectively improve hydrophone sensitivity through bending wave convergence, and can achieve broadband acoustic detection when the structure is coupled with liquid cavity resonators. These findings lay a solid foundation for the application of ABH structures in the design of underwater acoustic transducer.

     

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