Impedance Theory and Measurements on Porous Acoustic Liners
Impedance Theory and Measurements on Porous Acoustic Liners
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DOI：
10.2514/3.58844
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发表时间：
1977-08
影响因子：
2.2
通讯作者：
A. Bauer
中科院分区：
文献类型：
--
作者：
A. Bauer
点反应衬垫的阻抗由薄的多孔表面片组成，其背面是充满空气或多孔材料的空腔，已经用数学方法预测了有流管道的阻抗。数学模型已与实验结果进行了比较，通过使用两个麦克风技术的各种内衬安装在一个1英尺的管道与流动马赫数为0至0.6。预测和测量的声压被认为是在良好的协议内衬由单层的空气填充或多孔腔覆盖的薄多孔片。与空气腔衬相比，多孔腔衬具有更宽的衰减带宽和更高的高频衰减。由于多孔腔可能被认为是由多孔板层分隔的大量空气空间层的等效物，因此构造并测试了几个这样的多层衬垫。然而，多层衬垫的性能并不像多孔腔衬垫那样，并且尚未获得对多层衬垫的操作的充分理解。
The impedance of a point-reacting liner consisting of a thin, porous surface sheet backed by cavities filled with air or with porous materials has been predicted mathematically for a duct with flow. The mathematical model has been compared with experimental results obtained by using the two-microphone technique for various liners mounted in a 1-ft duct with flow at Mach numbers of 0 to 0.6. The predicted and the measured sound pressures were found to be in good agreement for liners consisting of a single layer of either air-filled or porous cavities covered by a thin porous sheet. As expected, the porous-cavity liners have a wider attenuated bandwidth and a higher attenuation at high frequencies than the air-cavity liners. Since porous cavities might be considered to be the equivalent of a large number of layers of air spaces separated by layers of porous plates, several such multilayer liners were constructed and tested. However, the multilayer liners did not perform like a porouscavity liner, and a full understanding of the operation of the multilayer liners is yet to be attained.