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.
Unsteady Simulations of Sound Propagation in Turbulent Flow Inside a Lined Duct
AIAA Journal ; 59 , 8 ; 3054-3070
2021-05-10
17 pages
Article (Journal)
Electronic Resource
English
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