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ONERA-NASA Cooperative Effort on Liner Impedance Eduction
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Author and Affiliation:
Primus, Julien(Office National d'Etudes et de Recherches Aeronautiques, Paris, France);
Piot, Estelle(Office National d'Etudes et de Recherches Aeronautiques, Paris, France);
Simon, Frank(Office National d'Etudes et de Recherches Aeronautiques, Paris, France);
Jones, Michael G.(NASA Langley Research Center, Hampton, VA, United States);
Watson, Willie R(NASA Langley Research Center, Hampton, VA, United States)
Abstract: As part of a cooperation between ONERA and NASA, the liner impedance eduction methods developed by the two research centers are compared. The NASA technique relies on an objective function built on acoustic pressure measurements located on the wall opposite the test liner, and the propagation code solves the convected Helmholtz equation in uniform ow using a finite element method that implements a continuous Galerkin discretization. The ONERA method uses an objective function based either on wall acoustic pressure or on acoustic velocity acquired above the liner by Laser Doppler Anemometry, and the propagation code solves the linearized Euler equations by a discontinuous Galerkin discretization. Two acoustic liners are tested in both ONERA and NASA ow ducts and the measured data are treated with the corresponding impedance eduction method. The first liner is a wire mesh facesheet mounted onto a honeycomb core, designed to be linear with respect to incident sound pressure level and to grazing ow velocity. The second one is a conventional, nonlinear, perforate-over-honeycomb single layer liner. Configurations without and with ow are considered. For the nonlinear liner, the comparison of liner impedance educed by NASA and ONERA shows a sensitivity to the experimental conditions, namely to the nature of the source and to the sample width.
Publication Date: May 27, 2013
Document ID:
20130013984
(Acquired Jul 19, 2013)
Subject Category: ACOUSTICS
Report/Patent Number: NF1676L-15558
Document Type: Conference Paper
Meeting Information: 19th AIAA/CEAS Aeroacoustics Conference; 27-29 May 2013; Berlin; Germany
Meeting Sponsor: American Inst. of Aeronautics and Astronautics; Reston, VA, United States
Contract/Grant/Task Num: WBS 473452.02.07.07.03.02
Financial Sponsor: NASA Langley Research Center; Hampton, VA, United States
Organization Source: Office National d'Etudes et de Recherches Aeronautiques; Paris, France
NASA Langley Research Center; Hampton, VA, United States
Description: 15p; In English; Original contains color illustrations
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: ACOUSTIC VELOCITY; LININGS; IMPEDANCE; SOUND PRESSURE; PRESSURE MEASUREMENT; FINITE ELEMENT METHOD; GALERKIN METHOD; DUCTS; WALL PRESSURE; NONLINEARITY
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