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Ultrasonic absorption characteristics of porous carbon–carbon ceramics with random microstructure for passive hypersonic boundary layer transition control

Wagner, Alexander and Hannemann, Klaus and Kuhn, Markus (2014) Ultrasonic absorption characteristics of porous carbon–carbon ceramics with random microstructure for passive hypersonic boundary layer transition control. Experiments in Fluids, 55 (6), pp. 1-9. Springer. DOI: 10.1007/s00348-014-1750-4 ISSN 0723-4864

Full text not available from this repository.

Official URL: http://link.springer.com/article/10.1007%2Fs00348-014-1750-4

Abstract

Preceding studies in the high enthalpy shock tunnel Göttingen of the German Aerospace Center (DLR) revealed that carbon fibre reinforced carbon ceramic (C/C) surfaces can be utilized to damp hypersonic boundary layer instabilities leading to a delay of boundary layer transition onset. To assess the ultrasonic absorption properties of the material, a test rig was set up to measure the reflection coefficient at ambient pressures ranging from 0.1 9 10^5 to 1 9 10^5 Pa. For the first time, broadband ultrasonic sound transducers with resonance frequencies of up to 370 kHz were applied to directly cover the frequency range of interest with respect to the second-mode instabilities observed in previous experiments. The reflection of ultrasonic waves from three flat plate test samples with a porous layer thickness between 5 and 30 mm was investigated and compared to an ideally reflecting surface. C/C was found to absorb up to 19 % of the acoustic power transmitted towards the material. The absorption characteristics were investigated theoretically by means of the quasi-homogeneous absorber theory. The experimental results were found to be in good agreement with the theory.

Item URL in elib:https://elib.dlr.de/89370/
Document Type:Article
Additional Information:Published online: 27 May 2014
Title:Ultrasonic absorption characteristics of porous carbon–carbon ceramics with random microstructure for passive hypersonic boundary layer transition control
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Wagner, Alexanderalexander.wagner (at) dlr.deUNSPECIFIED
Hannemann, Klausklaus.hannemann (at) dlr.deUNSPECIFIED
Kuhn, Markusmarkus.kuhn (at) dlr.deUNSPECIFIED
Date:2014
Journal or Publication Title:Experiments in Fluids
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:55
DOI :10.1007/s00348-014-1750-4
Page Range:pp. 1-9
Publisher:Springer
ISSN:0723-4864
Status:Published
Keywords:porous carbon–carbon ceramics, hypersonic boundary layer transition, ultrasonic waves, ultrasonically absorptive coatings (UAC)
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 - Numerische Verfahren und Simulation
Location: Göttingen , Stuttgart
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Spacecraft
Institute of Structures and Design > Space System Integration
Deposited By: Micknaus, Ilka
Deposited On:14 Jul 2014 15:38
Last Modified:06 Sep 2019 15:25

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