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Transient Fluid-Combustion Phenomena in a Model Scramjet

Laurence, Stuart and Karl, Sebastian and Martinez Schramm, Jan and Hannemann, Klaus (2013) Transient Fluid-Combustion Phenomena in a Model Scramjet. Journal of Fluid Mechanics, Vol. 722, pp. 85-120. Cambidge University Press. DOI: 10.1017/jfm.2013.56 ISSN 0022-1120

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Official URL: http://journals.cambridge.org/action/displayIssue?iid=8869548

Abstract

An experimental and numerical investigation of the unsteady phenomena induced in a hydrogen-fuelled scramjet combustor under high equivalence-ratio conditions is carried out, focusing on the processes leading up to unstart. The configuration for the study is the fuelled flowpath of the HyShot II flight experiment. Experiments are performed in the HEG reflected-shock wind tunnel, and results are compared with those obtained from unsteady numerical simulations. High-speed Schlieren and OH* chemiluminescence visualization, together with time-resolved surface pressure measurements, allow links to be drawn between the experimentally observed flow and combustion features. The transient flow structures signaling the onset of unstart are seen to take the form of an upstreampropagating shock train. Both the speed of propagation and the downstream location at which the shock train originates depend strongly on the equivalence ratio; however, the physical nature of the incipient shock system appears to be similar for different equivalence ratios. Both experiments and computations indicate that the primary mechanism responsible for the transient behaviour is thermal choking, though localised boundary-layer separation is observed to accompany the shock system as it moves upstream. In the numerical simulations, the global choking behavior is dictated by the limited region of maximum heat release near the shear layer between the injected hydrogen and the main flow: this leads to the idea of “local” thermal choking and results in a lower choking limit than suggested by a simple integral analysis. Such localised choking makes it possible for new quasi-steady flow topologies to arise, and these are observed in both experiments and simulation. Finally, a quasi-unsteady one-dimensional model is proposed to explain elements of the observed choking behaviour.

Item URL in elib:https://elib.dlr.de/75259/
Document Type:Article
Additional Information:first published online: 28 March 2013
Title:Transient Fluid-Combustion Phenomena in a Model Scramjet
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Laurence, StuartUNSPECIFIEDUNSPECIFIED
Karl, SebastianUNSPECIFIEDUNSPECIFIED
Martinez Schramm, JanUNSPECIFIEDUNSPECIFIED
Hannemann, KlausUNSPECIFIEDUNSPECIFIED
Date:2013
Journal or Publication Title:Journal of Fluid Mechanics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:Vol. 722
DOI :10.1017/jfm.2013.56
Page Range:pp. 85-120
Publisher:Cambidge University Press
ISSN:0022-1120
Status:Published
Keywords:Supersonic combustion, inlet unstart, scramjets, numerical modelling, unsteady gas dynamics
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 - Anlagen u. Messtechnik
Location: Göttingen
Institutes and Institutions:Institute of Aerodynamics and Flow Technology > Spacecraft
Deposited By: Laurence, Stuart
Deposited On:19 Mar 2012 16:28
Last Modified:31 Jul 2019 19:35

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