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Understanding Kelvin-Helmholtz Instability in Paraffin-Based Hybrid Rocket Fuels

Petrarolo, Anna and Kobald, Mario and Schlechtriem, S. (2018) Understanding Kelvin-Helmholtz Instability in Paraffin-Based Hybrid Rocket Fuels. Experiments in Fluids, 59 (4), p. 62. Springer. DOI: 10.1007/s00348-018-2516-1 ISSN 0723-4864

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Official URL: https://link.springer.com/article/10.1007%2Fs00348-018-2516-1

Abstract

Liquefying fuels show higher regression rates than the classical polymeric ones. They are able to form, along their burning surface, a low viscosity and surface tension liquid layer, which can become unstable (Kelvin--Helmholtz instability) due to the high velocity gas flow in the fuel port. This causes entrainment of liquid droplets from the fuel surface into the oxidizer gas flow. To better understand the droplets entrainment mechanism, optical investigations on the combustion behaviour of paraffin-based hybrid rocket fuels in combination with gaseous oxygen have been conducted in the framework of this research. Combustion tests were performed in a 2D single-slab burner at atmospheric conditions. High speed videos were recorded and analysed with two decomposition techniques. Proper orthogonal decomposition (POD) and independent component analysis (ICA) were applied to the scalar field of the flame luminosity. The most excited frequencies and wavelengths of the wave-like structures characterizing the liquid melt layer were computed. The fuel slab viscosity and the oxidizer mass flow were varied to study their influence on the liquid layer instability process. The combustion is dominated by periodic, wave-like structures for all the analysed fuels. Frequencies and wavelengths characterizing the liquid melt layer depend on the fuel viscosity and oxidizer mass flow. Moreover, for very low mass flows, no wavelength peaks are detected for the higher viscosity fuels. This is important to better understand and predict the onset and development of the entrainment process, which is connected to the amplification of the longitudinal waves.

Item URL in elib:https://elib.dlr.de/119134/
Document Type:Article
Title:Understanding Kelvin-Helmholtz Instability in Paraffin-Based Hybrid Rocket Fuels
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Petrarolo, Annaanna.petrarolo (at) dlr.dehttps://orcid.org/0000-0002-2291-2874
Kobald, Mariomario.kobald (at) dlr.dehttps://orcid.org/0000-0002-1708-3944
Schlechtriem, S.Stefan.Schlechtriem (at) dlr.deUNSPECIFIED
Date:5 March 2018
Journal or Publication Title:Experiments in Fluids
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:59
DOI :10.1007/s00348-018-2516-1
Page Range:p. 62
Publisher:Springer
ISSN:0723-4864
Status:Published
Keywords:Paraffin fuels, hybrid Propulsion, optical Investigation, POD, ICA, Oxygen, liquefying fuel
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 - Antriebsystemtechnik - Raketenantriebtests
Location: Lampoldshausen
Institutes and Institutions:Institute of Space Propulsion > Propellants
Deposited By: Kobald, Dr. Mario
Deposited On:06 Mar 2018 07:55
Last Modified:06 Sep 2019 15:25

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