Wang Xiaolin
Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080, China.
J Acoust Soc Am. 2007 Nov;122(5):2626-35. doi: 10.1121/1.2785041.
Rubber has traditionally been used for underwater sound absorption. Porous metal is a relatively lightweight material and also has higher strength than rubber. However, exactly how porous metals can be used as effective underwater sound absorbers remains unclear. This paper shows how to use porous metal absorbers so that they work well under water, even under fairly constrained conditions. A method of nondimensional analysis is proposed that allows identification of vital characteristics. This means that such characteristics can be varied and the absorbers themselves filled with different types of viscous fluids. Such analysis suggests that the sound absorption coefficient of porous metals does not always increase when there are either increases in porosity or decreases in average pore size. The same method of analysis can show how, by choice of the right characteristics to choose a suitable viscous fluid, a porous metal absorber can be built that takes up little space but still effectively absorbs underwater sounds at low frequencies.
传统上，橡胶一直被用于水下吸声。多孔金属是一种相对轻质的材料，并且比橡胶具有更高的强度。然而，多孔金属究竟如何能够用作有效的水下吸声器仍不清楚。本文展示了如何使用多孔金属吸声器，以便它们在水下，甚至在相当受限的条件下也能良好工作。提出了一种无量纲分析方法，该方法能够识别关键特性。这意味着可以改变这些特性，并在吸声器中填充不同类型的粘性流体。这种分析表明，当孔隙率增加或平均孔径减小时，多孔金属的吸声系数并不总是增加。同样的分析方法可以表明，通过选择合适的特性来选择合适的粘性流体，如何构建一种占用空间小但仍能有效吸收低频水下声音的多孔金属吸声器。
