| Title: | The effect of duct size, sample size, and fuel composition on concurrent flame spread over large cellulose samples in microgravity |
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| Authors: | ID Olson, Sandra L. (Author)
ID Ruff, Gary A. (Author)
ID Ferkul, Paul V. (Author)
ID Owens, Jay C. (Author)
ID Easton, John (Author)
ID Liao, Ya-Ting T. (Author)
ID T'ien, James S. (Author)
ID Toth, Balazs (Author)
ID Jomaas, Grunde (Author)
ID Fernandez-Pello, A. Carlos (Author)
ID Legros, Guillaume (Author)
ID Guibaud, Augustin (Author)
ID Fujita, Osamu (Author)
ID Smirnov, Nikolay (Author)
ID Urban, David L. (Author) |
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| Files: |  URL - Source URL, visit https://www.sciencedirect.com/science/article/pii/S0010218022005673
 PDF - Presentation file. (2,13 MB, This file will be accessible after 22.12.2024)
MD5: 70148DDD994A7ADB1A99975380A003AC
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| Language: | English |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: |  ZAG - Slovenian National Building and Civil Engineering Institute
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| Abstract: | Concurrent flame spread data for thermally-thin charring solid fuels are presented from Saffire and BASS experiments performed in habitable spacecraft for three duct sizes, five sample sizes, two materials, and two atmospheres. The flame spread rates and flame lengths were strongly affected by duct size even for the relatively large ducts (> 30 cm tall). A transient excess pyrolysis length (i.e., flame length overshoot) was observed for the cotton fabric that burned away, which indicates that the transient excess pyrolysis length phenomenon is caused by more than just the flame moving into the developing boundary layer thickness as was the case with the SIBAL sample. A burnout time, defined as the pyrolysis length divided by the flame spread rate, normalized the pyrolysis length histories into a single curve with a steady burnout time of 22 s for the SIBAL fabric. The transient excess pyrolysis length is hypothesized to be a post-ignition flame growth transient for the essentially two-dimensional flames where the burnout time becomes very long until the preheat and pyrolysis lengths develop. The three-dimensional flames over narrow samples have lateral thermal expansion and lateral oxygen diffusion which allows them to transition to a steady state length without the transient excess pyrolysis length. Surface temperature profiles, nondimensionalized by the pyrolysis length, indicate that the temperature profiles exhibit the same shape across the pyrolysis zone. A surface energy balance calculation in the preheat region revealed that the heat flux increased rapidly at the pyrolysis front to near the critical heat flux for ignition. An estimate of the acceleration of the inviscid core flow in the duct due to thermal expansion and developing boundary layers on the duct walls and the SIBAL sample surface seems to explain the observed spread rate trends across three duct sizes and multiple sample sizes. |
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| Keywords: | concurrent flame spread, microgravity, duct size, sample size, cellulose fabrics |
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| Publication status: | Published |
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| Publication version: | Author Accepted Manuscript |
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| Publication date: | 22.12.2022 |
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| Publisher: | Elsevier Science |
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| Year of publishing: | 2023 |
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| Number of pages: | str. 1-14 |
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| Numbering: | Vol. 248, [article no.] 112559 |
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| PID: | 20.500.12556/DiRROS-17650  |
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| UDC: | 62 |
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| ISSN on article: | 1556-2921 |
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| DOI: | 10.1016/j.combustflame.2022.112559 |
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| COBISS.SI-ID: | 143621379 |
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| Copyright: | © 2022 Elsevier Ltd. All rights reserved |
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| Note: | Nasl. z nasl. zaslona;
Opis vira z dne 1. 3. 2023;
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| Publication date in DiRROS: | 08.01.2024 |
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| Views: | 186 |
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| Downloads: | 38 |
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