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吸声材料布置方式对声学黑洞吸声体性能的影响

Influence of Damping Material Arrangement on the Performance of Sonic Black Hole Absorbers

  • 摘要: 声学黑洞吸声结构(sonic black hole, SBH)是一种内部沿中线向两侧布置有按指数规律变化长度的隔板所构成的吸声体。在SBH中,声波传播速度逐渐下降,从而产生声学黑洞效应;理想情况下,声波不会反射,可实现完美吸声。然而,实际SBH吸声体的吸声性能受截断效应和加工精度影响,需布置阻尼材料方可获得较好的吸声性能。本文首先对SBH的吸声性能进行理论分析,继而设计了不同的阻尼材料布置方案。仿真计算结果表明,吸声体声压汇集于SBH底部的1至5号缝隙中,这些缝隙是阻尼材料的最佳布置位置。最后进行了实验验证,结果表明:仅在SBH末端布置阻尼材料无法有效提升其吸声性能。而在SBH结构底部的1至5号缝隙中布置阻尼材料,则可有效提升其吸声性能。

     

    Abstract: The sonic black hole (SBH) absorber consists of an acoustic metamaterial structure formed by partitions arranged symmetrically along its central axis, with partition lengths varying exponentially toward both ends. Within this structure, the speed of sound gradually decreases, producing an acoustic black hole effect. Ideally, incident sound waves would experience no reflection, resulting in perfect absorption. However, the actual acoustic performance of SBH absorbers is limited by truncation effects and manufacturing imperfections, necessitating the incorporation of damping material to achieve satisfactory absorption. This study begins with a theoretical analysis of the acoustic behavior of the SBH absorber. Subsequently, various layout schemes for the damping material are designed and evaluated. Simulation results indicate that sound pressure concentrates in the 1st through 5th gaps at the bottom of the SBH absorber—identifying these gaps as the optimal locations for damping material placement. Finally, experimental validation is conducted. The results show that placing damping material only at the SBH terminus does not effectively enhance absorption performance. In contrast, significantly improved acoustic absorption is achieved when damping material is placed in the 1st through 5th gaps at the bottom of the SBH.

     

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