elib
DLR-Header
DLR-Logo -> http://www.dlr.de
DLR Portal Home | Imprint | Privacy Policy | Contact | Deutsch
Fontsize: [-] Text [+]

Towards Impedance Characterization of Carbon-Carbon Ultrasonically Absorptive Coatings via the Inverse Helmholtz Problem

Patel, Danish and Gupta, Prateek and Scalo, Carlo and Rothermel, Thomas and Kuhn, Markus (2017) Towards Impedance Characterization of Carbon-Carbon Ultrasonically Absorptive Coatings via the Inverse Helmholtz Problem. 55th AIAA Aerospace Sciences Meeting, AIAA SciTech Forum, 9.-13. Jan. 2017, Grapevine, USA. DOI: 10.2514/6.2017-0460

Full text not available from this repository.

Official URL: https://doi.org/10.2514/6.2017-0460

Abstract

We present a numerical method to determine the complex acoustic impedance at the open surface of an arbitrarily shaped cavity, associated to an impinging planar acoustic wave with a given wavenumber vector and frequency. We have achieved this by developing the first inverse Helmholtz Solver (iHS), which implicitly reconstructs the complex acoustic waveform - at a given frequency - up to the unknown impedance boundary, hereby providing the spatial distribution of impedance as a result of the calculation for that given frequency. We show that the algebraic closure conditions required by the inverse Helmholtz Problem are physically related to the assignment of the spatial distribution of the pressure phase over the unknown impedance boundary. The iHS is embarassingly parallelizable over the frequency domain allowing for the straightforward determination of the full broadband impedance at every point of the target boundary. In this paper, we restrict our Analysis to two-dimensions only. We first validate our results against Rott's quasi one-dimensional thermoacoustic theory for viscid and inviscid constant-area rectangular ducts, test our iHS in a fully unstructured fashion with a geometrically complex cavity, and finally, present a simplified, two-dimensional Analysis of a sample of carbon-carbon ultrasonically absorptive coatings (C/C UACs) manufactured in DLR-Stuttgart, and used in the hypersonic transition delay experiments by Wagner et al. in AIAA 2012-5865. The final goal is to model C/C UACs with multi-oscillator Time Domain Impedance Boundary Conditions (TDIBC) developed by Lin et al. in JFM (2016) to be applied in direct numerical simulations (DNS) focused on the overlying boundary layer, eliminating the need to simultaneously resolve the microscopic porous structure of the C/C UACs.

Item URL in elib:https://elib.dlr.de/119461/
Document Type:Conference or Workshop Item (Speech)
Additional Information:AIAA 2017-0460
Title:Towards Impedance Characterization of Carbon-Carbon Ultrasonically Absorptive Coatings via the Inverse Helmholtz Problem
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Patel, DanishPurdue UniversityUNSPECIFIED
Gupta, PrateekPurdue UniversityUNSPECIFIED
Scalo, CarloPurdue UniversityUNSPECIFIED
Rothermel, ThomasThomas.Rothermel (at) dlr.deUNSPECIFIED
Kuhn, MarkusMarkus.Kuhn (at) dlr.dehttps://orcid.org/0000-0002-0633-2327
Date:9 January 2017
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
DOI :10.2514/6.2017-0460
Page Range:pp. 1-14
Status:Published
Keywords:ACOUSTIC DAMPING, BOUNDARY LAYER TRANSITION DELAY, CARBON/CARBON, CERAMIC COATING, HYPERSONIC FLOW, INVERSE HELMHOLTZ PROBLEM, ULTRASONICALLY ABSORPTIVE COATING (UAC)
Event Title:55th AIAA Aerospace Sciences Meeting, AIAA SciTech Forum
Event Location:Grapevine, USA
Event Type:international Conference
Event Dates:9.-13. Jan. 2017
Organizer:AIAA
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transport
DLR - Research area:Raumfahrt
DLR - Program:R RP - Raumtransport
DLR - Research theme (Project):R - Raumfahrzeugsysteme - Konzepte und Entwurf, R - Raumfahrzeugsysteme - Numerische Verfahren und Simulation, L - Military Technologies
Location: Stuttgart
Institutes and Institutions:Institute of Structures and Design > Space System Integration
Deposited By: Kuhn, Markus
Deposited On:14 Jun 2018 15:41
Last Modified:14 Jun 2018 15:41

Repository Staff Only: item control page

Browse
Search
Help & Contact
Information
electronic library is running on EPrints 3.3.12
Copyright © 2008-2017 German Aerospace Center (DLR). All rights reserved.