The acoustic liner of the nacelle of an aeroengine is the most important noise reduction device of the engine. In order to establish an accurate impedance model related to the structure and acoustic performance of the acoustic liner, it is necessary to analyze the acoustic impedance eduction technology of the liner. This paper compared and analyzed the difference between two liner impedance eduction techniques-an situ impedance eduction method and straightforward method. The same flow tube acoustic test platform, liners with controllable deviation, and the repeatability test of impedance measurement were used to ensure the basis for the comparison of the two impedance extraction methods. Two impedance measurement methods were used to obtain the acoustic impedance of single-degree-of-freedom acoustic liner and double-freedom liner. The results show that the measurement results from the two impedance eduction methods are consistent with each other in the mid-range and high-range, and there are significant differences in the low-frequency ranges. The comparative analysis shows that compared with the straightforward method, the in situ method is applicable to a wider frequency range, can resist the local acoustic impedance characteristics of the acoustic liner, and has a small limitation on the size of the acoustic liner, but it needs to break the structure of the liner. It is suitable for the traditional liner. Compared with the in situ method, the straightforward method measures the overall impedance characteristics of the acoustic liner. It can obtain accurate impedance results in middle and high frequency range without the need to break the structure, and used in a wider range of plate-type sound-absorbing materials.
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徐健,薛东文,杨嘉丰. 两种声衬阻抗提取方法的对比[J]. 科学技术与工程, 2022, 22(13): 5498-5505. Xu Jian, Xue Dongwen, Yang Jiafeng. Comparative Study of Two Kinds of Impedance Eduction Methods[J]. Science Technology and Engineering,2022,22(13):5498-5505.