This paper presents results for five uniform and two multizone liners based on data acquired in the NASA Langley Grazing Flow Impedance Tube. Two methods, Prony and CHE, are used to educe the impedance spectra for each of these liners for many test conditions. The Prony method is efficient and generally provides accurate results for uniform liners, but is not well suited for multizone liners. The CHE method supports assessment of both uniform and multizone liners, but is much more computationally expensive. The results from these liners demonstrate the efficacy of both eduction methods, but also clearly demonstrate that sufficient attenuation is required to support accurate impedance eduction. For the liners considered in this study, the data indicate approximately 3 dB attenuation is needed for each zone of a multizone liner in order to ensure quality impedance eduction results. This study was conducted in response to two acoustic liner research challenges in support of a collaboration of multiple national laboratories under the International Forum for Aviation Research.

本文根据 NASA Langley Grazing Flow Impedance Tube 中获得的数据展示了五个均匀衬里和两个多区域衬里的结果。Prony 和 CHE 两种方法用于推导出这些衬垫在许多测试条件下的阻抗谱。Prony 方法是有效的，通常为均匀衬管提供准确的结果，但不太适合多区域衬管。CHE 方法支持对均匀衬管和多区域衬管的评估，但计算成本要高得多。这些衬垫的结果证明了两种导出方法的有效性，但也清楚地表明需要足够的衰减来支持准确的阻抗导出。对于本研究中考虑的衬垫，数据表明，多区域衬垫的每个区域需要大约 3 dB 的衰减，以确保高质量的阻抗消除结果。这项研究是为了应对两个声学衬垫研究挑战而进行的，以支持国际航空研究论坛下的多个国家实验室的合作。