Numerical Analysis of Acoustic Liner Performance in grazing flow

2019 ◽  
Author(s):  
Shunji Enomoto ◽  
Tatsuya Ishii ◽  
Toshio Nishizawa ◽  
Hidemi Toh
Keyword(s):  
Numerical Analysis ◽  
Acoustic Liner ◽  
Grazing Flow

Impedance eduction for uniform and multizone acoustic liners

2021 ◽  
pp. 1475472X2110238
Author(s):  
Michael G Jones ◽  
Douglas M Nark ◽  
Brian M Howerton
Keyword(s):  
Impedance Spectra ◽  
International Forum ◽  
Acoustic Liners ◽  
Prony Method ◽  
Research Challenges ◽  
Test Conditions ◽  
Acoustic Liner ◽  
Flow Impedance ◽  
Grazing Flow ◽  
Computationally Expensive

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.

scholarly journals Design and optimization of acoustic liners with a shear grazing flow: OPAL software platform description

2021 ◽  
Vol 263 (6) ◽  
pp. 508-518
Author(s):  
Frank Simon ◽  
R. Roncen ◽  
P. Vuillemin ◽  
P. Klotz ◽  
Fabien Méry ◽  
...  
Keyword(s):  
Transmission Loss ◽  
Low Frequency ◽  
Total Sample ◽  
Software Platform ◽  
Linearized Euler Equations ◽  
Design And Optimization ◽  
Acoustic Liners ◽  
Acoustic Liner ◽  
Frequency Regime ◽  
Grazing Flow

In the context of aircraft noise reduction in varied applications where a cold or hot shear grazing flow is present (i.e., engine nacelle, combustion chamber, jet pump, landing gear), improved acoustic liner solutions are being sought. This is particularly true in the low-frequency regime, where space constraints limit the efficiency of conventional liner technology. Therefore, liner design must take into account the dimensional and phenomenological characteristics of constituent materials, assembly specifications and industrial requirements involving multiphysical phenomena. To perform the single/multi-objective optimization of complex meta-surface liner candidates, a software platform coined OPAL (OPtimisation of Acoustic Liners) was developed. Its first goal is to allow the user to assemble a large panel of parallel/serial elementary acoustic layers along a given duct. Then, the physical properties of this liner can be optimized, relatively to weighted objectives, for a given flow and frequency range: impedance target, maximum absorption coefficient or transmission loss with a total sample size and weight... The presentation will focus on the different elementary bricks and assembly of a problem (from 0D analytical coarse designs in order to reduce the parameter space, up to 2D plan or axisymmetric high-order Discontinuous Galerkin simulations of the Linearized Euler Equations).

scholarly journals Near-wall aerodynamic response of an acoustic liner to harmonic excitation with grazing flow

2019 ◽  
Vol 60 (9) ◽  
Author(s):  
Olivier Léon ◽  
Fabien Méry ◽  
Estelle Piot ◽  
Claudia Conte
Keyword(s):  
Harmonic Excitation ◽  
Acoustic Liner ◽  
Grazing Flow ◽  
Near Wall

Experimental validation of numerical simulations for an acoustic liner in grazing flow: Self-noise and added drag

2014 ◽  
Vol 333 (13) ◽  
pp. 2831-2854 ◽  
Author(s):  
Christopher K.W. Tam ◽  
Nikolai N. Pastouchenko ◽  
Michael G. Jones ◽  
Willie R. Watson
Keyword(s):  
Numerical Simulations ◽  
Experimental Validation ◽  
Acoustic Liner ◽  
Grazing Flow

Validation of a Time- and Frequency-Domain Grazing Flow Acoustic Liner Model

AIAA Journal ◽  
2009 ◽  
Vol 47 (8) ◽  
pp. 1841-1848 ◽  
Author(s):  
Markus O. Burak ◽  
Mattias Billson ◽  
Lars-Erik Eriksson ◽  
Stéphane Baralon
Keyword(s):  
Frequency Domain ◽  
Acoustic Liner ◽  
Grazing Flow

A review of variable-impedance acoustic liner concepts developed at NASA

2021 ◽  
Vol 263 (5) ◽  
pp. 1633-1644
Author(s):  
Michael Jones
Keyword(s):  
Prediction Models ◽  
Normal Incidence ◽  
Wide Frequency Range ◽  
Acoustic Properties ◽  
Surface Porosity ◽  
Acoustic Liner ◽  
Impedance Tubes ◽  
Flow Impedance ◽  
Grazing Flow ◽  
Langley Research Center

This paper presents results attained in the NASA Langley Research Center test rigs using concepts for which the impedance varies over the surface of the liner. These liners are typically designed for significant sound absorption over a wide frequency range, but it is also possible to tune the design to achieve increased absorption at selected frequencies. A brief review is provided regarding a number of variable-impedance concepts. The first is a modified version of a conventional two-layer liner, in which the embedded septum location and acoustic properties are different for adjacent core chambers. Two concepts employ core chambers with different lengths, one with bent chambers to allow packaging within a limited volume, and the other with shared inlet ports to reduce the surface porosity. The last employs a perforated facesheet in which the hole diameter and porosity are varied over the surface of the liner. Data acquired in the NASA normal incidence and grazing flow impedance tubes are used to demonstrate the capabilities of these concepts. Impedance prediction models are also presented for comparison with these measured data.

Proposal of Acoustic Liners Combined with Fine-Perforated-Film

2021 ◽  
Vol 263 (1) ◽  
pp. 5475-5484
Author(s):  
Yo Murata ◽  
Tatsuya Ishii ◽  
Shunji Enomoto ◽  
Hideshi Oinuma ◽  
Kenichiro Nagai ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Absorption Efficiency ◽  
Acoustic Energy ◽  
Experimental Result ◽  
Acoustic Liners ◽  
Acoustic Liner ◽  
The Face ◽  
Grazing Flow ◽  
Face Plate ◽  
Perforated Film

This paper deals with a resonant type liner panel with a special surface structure. A typical resonant type liner panel generally consists of a perforated face plate, cells, and a back rigid plate. One of the technical challenges of the acoustic liners applied to the future ultra-high bypass ratio engines is to increase the sound absorption efficiency under grazing conditions because the nacelle, covering of the engine, tends to reduce its length and the lined area. It is known that the sound absorption of the conventional liners tends to deteriorate as grazing flow increases. The authors introduced a special thin acoustically transparent film over the face plate of the acoustic liner. The film, a fine perforated film (FPF), is expected to prevent the interaction of the grazing flow with the opening of the liner face plate. An experimental result with a flow duct rig in JAXA confirmed that the proposed combination of the acoustic liner and the FPF improved the absorption in acoustic energy under grazing conditions, compared with the sole acoustic liner and simple treatment of the FPF.

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