Laboratoire d'Acoustique de l'Université du Maine, Unité Mixte de Recherche 6613 Centre National de la Recherche Scientifique, Av. O. Messiaen, 72085 Le Mans Cedex 9, France.
J Acoust Soc Am. 2011 Jul;130(1):52-60. doi: 10.1121/1.3586789.
This paper deals with experimental investigation of the lined wall boundary condition in flow duct applications such as aircraft engine systems or automobile mufflers. A first experiment, based on a microphone array located in the liner test section, is carried out in order to extract the axial wavenumbers with the help of an "high-accurate" singular value decomposition Prony-like algorithm. The experimental axial wavenumbers are then used to provide the lined wall impedance for both downstream and upstream acoustic propagation by means of a straightforward impedance education method involving the classical Ingard-Myers boundary condition. The results show that the Ingard-Myers boundary condition fails to predict with accuracy the acoustic behavior in a lined duct with flow. An effective lined wall impedance, valid whatever the direction of acoustic propagation, can be suitably found from experimental axial wavenumbers and a modified version of the Ingard-Myers condition with the form inspired from a previous theoretical study [Aurégan et al., J. Acoust. Soc. Am. 109, 59-64 (2001)]. In a second experiment, the scattering matrix of the liner test section is measured and is then compared to the predicted scattering matrix using the multimodal approach and the lined wall impedances previously deduced. A large discrepancy is observed between the measured and the predicted scattering coefficients that confirms the poor accuracy provided from the Ingard-Myers boundary condition widely used in lined duct applications.
本文针对飞机发动机系统或汽车消声器等流动管道应用中的衬里壁边界条件进行了实验研究。首先进行了一项基于位于衬里测试段的麦克风阵列的实验，以帮助通过“高精度”奇异值分解 Prony 样算法提取轴向波数。然后，通过涉及经典 Ingard-Myers 边界条件的简单阻抗教育方法，使用实验轴向波数为下游和上游声传播提供衬里壁阻抗。结果表明，Ingard-Myers 边界条件无法准确预测带流衬里管道中的声行为。可以从实验轴向波数和受先前理论研究启发的 Ingard-Myers 条件的修改版本中找到适用于任何声传播方向的有效衬里壁阻抗[奥雷根等人，J. Acoust. Soc. Am. 109, 59-64（2001）]。在第二个实验中，测量了衬里测试段的散射矩阵，然后使用多模态方法和之前推导出的衬里壁阻抗将其与预测的散射矩阵进行比较。观察到测量和预测的散射系数之间存在很大差异，这证实了广泛用于衬里管道应用的 Ingard-Myers 边界条件提供的精度很差。
