Experimental investigation of the acoustic black hole for sound absorption in air
Experimental investigation of the acoustic black hole for sound absorption in air
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发表时间：
2015
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通讯作者：
A. Ouahabi;V. Krylov;D. O'Boy
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作者：
A. Ouahabi;V. Krylov;D. O'Boy
本文叙述了声黑洞在空气中吸声的首次实验研究结果。为了实现所需的声速随传播距离的幂律衰减，使用了先前由Mironov和Pislyakov（2002）提出的由准周期肋状结构制成的可变阻抗壁的非均匀声波导。由这些肋状结构形成的两个不同的声黑洞样品已经被制造出来，以提供声波速度随距离的线性和二次减小。在末端插入了小块的吸收多孔材料。在100 ~ 1000hz的频率范围内测量了入射到黑洞上的导声模式的反射系数。结果表明，在不使用额外吸波材料的情况下，有可能显著降低声反射。然而，与预期相反，吸收材料的引入并没有引起声反射系数的进一步显著降低。
In the present paper, the results of the first experimental investigation of the acoustic black hole for sound absorption in air are described. To achieve the required power-law decrease in sound velocity with propagation distance the inhomogeneous acoustic waveguides earlier proposed by Mironov and Pislyakov (2002) and made of quasi-periodic ribbed structures materialising walls of variable impedance have been used. Two different samples of acoustic black holes formed by these ribbed structures have been manufactured to provide linear and quadratic decreases in acoustic wave velocity with distance. Small pieces of absorbing porous material have been inserted at the end. Measurements of the reflection coefficients for guided acoustic modes incident on the black holes have been carried out in the frequency range of 100-1000 Hz. The results show the possibility of significant reduction in the acoustic reflection without using additional absorbing materials. However, contrary to the expectations, the introduction of absorbing materials did not cause further noticeable reduction in the sound reflection coefficients.