Aurégan Yves, Pagneux Vincent
Laboratoire d'Acoustique de l'Université du Maine, Unité Mixte de Recherche 6613, Centre National de la Recherche Scientifique, Avenue O Messiaen, F-72085 LE MANS Cedex 9, France.
J Acoust Soc Am. 2015 Aug;138(2):605-13. doi: 10.1121/1.4923450.
The acoustic propagation in lined flow duct with purely reactive impedance at the wall is considered. This reacting liner has the capability to reduce the speed of sound, and thus to enhance the interaction between the acoustic propagation and the low Mach number flow ( M≃0.3). At the lower frequencies, there are typically four acoustic or hydrodynamic propagating modes, with three of them propagating in the direction of the flow. Above a critical frequency, there are only two propagating modes that all propagate in the direction of the flow. From the exact two-dimensional formulation an approximate one-dimensional model is developed to study the scattering of acoustic waves in a straight duct with varying wall impedance. This simple system, with a uniform flow and with non-uniform liner impedance at the wall, permits to study the scattering between regions with different wave characteristics. Several situations are characterized to show the importance of negative energy waves, strong interactions between acoustic and hydrodynamic modes, or asymmetric scattering.
考虑了壁面具有纯电抗阻抗的衬里流道中的声传播。这种反应性衬里有能力降低声速，从而增强声传播与低马赫数流（M≃0.3）之间的相互作用。在较低频率下，通常有四种声或流体动力传播模式，其中三种沿流动方向传播。高于临界频率时，只有两种传播模式，且都沿流动方向传播。从精确的二维公式出发，开发了一个近似的一维模型，以研究声波在具有变化壁面阻抗的直管中的散射。这个简单的系统，具有均匀流且壁面衬里阻抗不均匀，允许研究具有不同波特性的区域之间的散射。描述了几种情况，以显示负能量波的重要性、声模式与流体动力模式之间的强相互作用或不对称散射。
