Experimental Investigations of Quasi-flat Acoustic Absorbers Enhanced by Metamaterial Layers
Experimental Investigations of Quasi-flat Acoustic Absorbers Enhanced by Metamaterial Layers
复制标题
DOI：
--
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Эль Уахаби;Университет;Лафборо;Университет Лафборо
中科院分区：
文献类型：
--
作者：
Эль Уахаби;Университет;Лафборо;Университет Лафборо
用于噪声控制的吸声器的效率可以通过提供从空气的阻抗到所讨论的吸声材料的阻抗的平滑过渡来提高。在本工作中，这种平滑的过渡是通过应用由固体圆柱体（管）的准周期阵列形成的梯度折射率超材料层来实现的，其中它们的外径从面向开放空气的管的外部行朝向面向吸收多孔层的内部行逐渐增加。如果声波波长比阵列的周期性大得多，则这种结构会使声阻抗朝向内排圆柱体逐渐增加。这使得开发人员能够实现空气和多孔吸收材料之间的几乎完美的阻抗匹配，例如海绵，玻璃纤维等。在本工作中，在500-3000 Hz的频率范围内进行了广泛的测量，从不同的吸收材料结合匹配的超材料层形成的黄铜管阵列的声音反射系数。声的垂直入射和斜入射都被考虑过。NOISE理论与实践3的结果表明，匹配超材料层的存在大大降低了声音反射系数，从而提高了吸声器的效率。声学超材料;准平板吸声体;阻抗匹配;声反射。
The efficiency of acoustic absorbers used for noise control can be improved by providing a smooth transition from the impedance of air to the impedance of the absorbing material in question. In the present work, such a smooth transition is materialised via application of gradient index metamaterial layers formed by quasi-periodic arrays of solid cylinders (tubes) with their external diameters gradually increasing from the external row of tubes facing the open air towards the internal row facing an absorbing porous layer. If acoustic wavelengths are much larger than the periodicity of the array, such a structure provides a gradual increase in the acoustic impedance towards the internal row of cylinders. This allows the developer to achieve an almost perfect impedance matching between the air and porous absorbing materials, such as sponges, fibreglass, etc. In the present work, a wide range of measurements of sound reflection coefficients from different absorbing materials combined with matching metamaterial layers formed by the arrays of brass tubes have been carried out at the frequency range of 500-3000 Hz. Both normal and oblique incidence of sound have been considered. The results NOISE Theory and Practice 3 show that the presence of matching metamaterial layers brings substantial reduction in sound reflection coefficients, thus increasing the efficiency of acoustic absorbers. Ключевые слова: Acoustic metamaterials; Quasi-flat acoustic absorber; Impedance matching; Acoustic reflection.