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Flame-acoustic response measurements in a high-pressure, 42-injector, cryogenic rocket thrust chamber

Armbruster, Wolfgang and Hardi, Justin and Oschwald, Michael (2020) Flame-acoustic response measurements in a high-pressure, 42-injector, cryogenic rocket thrust chamber. Proceedings of the Combustion Institute. Elsevier. doi: 10.1016/j.proci.2020.05.020. ISSN 1540-7489.

[img] PDF - Postprint version (accepted manuscript)

Official URL: https://www.sciencedirect.com/science/article/pii/S1540748920300201?via%3Dihub


This work presents measurements of acoustically driven flame dynamics in a 42-element, cryogenic oxygen-hydrogen rocket thrust chamber under supercritical injection conditions. The experiment shows self-excited combustion instabilities for certain operating conditions, and this work describes the nature of the flame dynamics driving the acoustic field, as far as it can be ascertained from state-of-the-art optical measurements. Optical access has been realized in the combustion chamber with both fibre-optical probes and a viewing window. The probes collect point-like measurements of filtered OH* radiation. Their signals were used to calculate the gain and phase of intensity oscillations with respect to acoustic pressure for both stable and unstable operating conditions. Through the window, synchronized high-speed imaging of the flame in filtered OH* and blue radiation wavelengths was collected. The 2D flame response was related to the local acoustic pressure to investigate the distributed intensity and phase relationships. The flame response from OH* measurements is in agreement with the theory of Rayleigh. For stable conditions the oscillations of combustion and pressure were out of phase, whereas for an excited chamber 1T mode the oscillations were closely in phase. The integrated Rayleigh index from blue imaging was not consistent with the OH* results. The reason lies in the depth of field captured by this type of imaging, and must be used in a complementary fashion together with OH* imaging. The flame response values and 2D visualization presented in this work are expected to be of value for the validation of numerical modelling of combustion instabilities.

Item URL in elib:https://elib.dlr.de/137686/
Document Type:Article
Title:Flame-acoustic response measurements in a high-pressure, 42-injector, cryogenic rocket thrust chamber
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Armbruster, WolfgangUNSPECIFIEDhttps://orcid.org/0000-0002-4859-4173UNSPECIFIED
Hardi, JustinUNSPECIFIEDhttps://orcid.org/0000-0003-3258-5261UNSPECIFIED
Oschwald, MichaelUNSPECIFIEDhttps://orcid.org/0000-0002-9579-9825UNSPECIFIED
Journal or Publication Title:Proceedings of the Combustion Institute
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Keywords:combustion instabilities; liquid propellant rocket engines; flame visualization; transcritical injection
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transportation
DLR - Research area:Raumfahrt
DLR - Program:R RP - Space Transportation
DLR - Research theme (Project):R - Reusable Space Systems and Propulsion Technology
Location: Lampoldshausen
Institutes and Institutions:Institute of Space Propulsion > Rocket Propulsion
Deposited By: Hanke, Michaela
Deposited On:19 Nov 2020 08:19
Last Modified:23 Oct 2023 14:13

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