Bradley, D, Lawes, M orcid.org/0000-0002-8693-7536, Mumby, R et al. (1 more author) (2019) The stability of laminar explosion flames. Proceedings of the Combustion Institute, 37 (2). pp. 1807-1813. ISSN 1540-7489
Abstract
The paper presents the results of a fundamental experimental and theoretical study of Darrieus-Landau, thermo-diffusive, instabilities in atmospheric explosions, and, on a smaller scale, in laboratory explosions in closed vessels. Pressure dependencies were sought to exploit the leading role of the Peclet number in the phenomena, so that similar Peclet numbers were achieved in both instances. However, in the large atmospheric explosions a large Peclet number was achieved by the distance scale of the fireball, whereas in the closed vessel explosion it was achieved at a higher pressure by a much smaller flame, but because of the higher pressure, one endowed with a small laminar flame thickness. This study covers a much wider range of fuels and of pressures and the dependencies of the phenomena on both of these were carefully studied, although, for the atmospheric explosions, the data only covered propane and methane. The roles of both Markstein and Peclet numbers become clear and give rise to a more fundamental correlating parameter, a critical Karlovitz number, Kcl, for flame stability. This is based on the flame stretch rate, normalised by its muliplication by the chemical reaction time in a laminar flame. The experimetnally measured dependencies of this key parameter on pressure and Markstein number are reported for the first time for so many different fuels. The critical Karlovitz number for flame stability decreases with increase in the strain rate Markstein number. As a result, it is possible to predict the extent of the unstable regime for laminar flames as a function of Masr and pressure. Such data can be used to estimate the severity of large scale atmospheric explosions. As Masr becomes highly negative, the regime of stability is markedly reduced.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 Published by Elsevier Inc. on behalf of The Combustion Institute. This is an author produced version of a paper published in Proceedings of the Combustion Institute. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Darrieus–Landau; Thermo-diffusive instabilities; Large-scale explosions; Critical Peclet number; Critical Karlovitz number |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mechanical Engineering (Leeds) > Institute of Engineering Thermofluids, Surfaces & Interfaces (iETSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 Aug 2018 09:37 |
Last Modified: | 02 Aug 2019 00:43 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.proci.2018.07.067 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:134157 |