This paper presents two enhancements of the efficient broadband time-domain impedance model proposed by Dragna, Pineau, and Blanc-Benon in 2015. It treats lined walls in the framework of the macroscopic concept of locally reacting acoustic impedance, and allows the formulation of the time-domain impedance boundary condition in the form of a set of ordinary differential equations. The first, minor, enhancement adjusts the model for scale-resolving approaches to turbulence in flows over lined surfaces, whereas the second one presents an extension that accounts for a dependence of the impedance on the level of wall pressure fluctuations, typical of many acoustic liners. The enhanced model is implemented in the high-fidelity numerical system developed by the authors earlier for aeroengine fan-noise prediction. It is then validated by computations of the sound propagation in the NASA Grazing Impedance Tube with turbulent grazing flow and of the attenuation of the noise emitted by NASA’s high-bypass-ratio turbofan model, due to acoustic treatment of the fan duct walls. The computations are performed in the framework of 2D and 3D problem statements with the use of the unsteady Reynolds-averaged Navier–Stokes equations (URANS) and the zonal URANS-wall modeled large eddy simulation approaches to turbulence representation.

本文介绍了Dragna，Pineau和Blanc-Benon在2015年提出的有效宽带时域阻抗模型的两个增强功能。它在局部反应声阻抗的宏观概念的框架内处理衬砌墙，并允许制定一组时域微分方程形式的时域阻抗边界条件。第一个较小的增强功能调整了用于衬砌表面上的湍流的尺度解析方法的模型，而第二个则提供了一种扩展，该扩展说明了阻抗对壁压力波动水平的依赖性，这是许多隔音衬管的典型特征。增强的模型在作者先前开发的用于航空发动机风扇噪声预测的高保真数值系统中实现。然后通过计算在湍流掠掠流中在NASA放牧阻抗管中的声音传播以及由于对风扇风道壁进行的声学处理而使NASA的高旁路比涡轮风扇模型发出的噪声衰减进行验证。计算是在2D和3D问题陈述的框架内进行的，使用了不稳定的雷诺平均Navier-Stokes方程（URANS）和区域URANS-wall建模的大涡模拟来表示湍流。