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Author (down) Verdugo, I.; Cruz, J.J.; Alvarez, E.; Reszka, P.; da Silva, L.F.F.; Fuentes, A.
Title Candle flame soot sizing by planar time-resolved laser-induced incandescence Type
Year 2020 Publication Scientific Reports Abbreviated Journal Sci Rep
Volume 10 Issue 1 Pages 12 pp
Keywords
Abstract Soot emissions from flaming combustion are relevant as a significant source of atmospheric pollution and as a source of nanomaterials. Candles are interesting targets for soot characterization studies since they burn complex fuels with a large number of carbon atoms, and yield stable and repeatable flames. We characterized the soot particle size distributions in a candle flame using the planar two-color time-resolved laser induced incandescence (2D-2C TiRe-LII) technique, which has been successfully applied to different combustion applications, but never before on a candle flame. Soot particles are heated with a planar laser sheet to temperatures above the normal flame temperatures. The incandescent soot particles emit thermal radiation, which decays over time when the particles cool down to the flame temperature. By analyzing the temporal decay of the incandescence signal, soot particle size distributions within the flame are obtained. Our results are consistent with previous works, and show that the outer edges of the flame are characterized by larger particles (approximate to 60 nm), whereas smaller particles (approximate to 25 nm) are found in the central regions. We also show that our effective temperature estimates have a maximum error of 100 K at early times, which decreases as the particles cool.
Address [Verdugo, Ignacio; Jose Cruz, Juan; Alvarez, Emilio; Fuentes, Andres] Univ Tecn Federico Santa Maria, Dept Ind, Av Espana 1680,Casilla 110-V, Valparaiso, Chile, Email: andres.fuentes@usm.cl
Corporate Author Thesis
Publisher Nature Publishing Group Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2045-2322 ISBN Medium
Area Expedition Conference
Notes WOS:000548564900078 Approved
Call Number UAI @ eduardo.moreno @ Serial 1178
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Author (down) Thomsen, M.; Cruz, J.J.; Escudero, F.; Fuentes, A.; Fernandez-Pello, C.; Gollner, M.; Urban, D.L.; Ruff, G.A.
Title Determining flame temperature by broadband two color pyrometry in a flame spreading over a thin solid in microgravity Type
Year 2023 Publication Proceedings Of The Combustion Institute Abbreviated Journal Proc. Combust. Inst.
Volume 39 Issue 3 Pages 3909-3918
Keywords Broadband pyrometry; Soot temperature; Boundary layer diffusion flame; Concurrent flame spread; Sibal material
Abstract Fire spread inside a spacecraft is a constant concern in space travel. Understanding how the fire grows and spreads, and how it can potentially be extinguished is critical for planning future missions. The conditions in-side a spacecraft can greatly vary from those encountered on earth, including microgravity, low velocity flows, reduced ambient pressure and high oxygen, and thus affecting the combustion processes. In microgravity, the contributions of thermal radiation from gaseous species and soot can play a critical role in the spread of a flame and the problem has not been fully understood yet. The overall objective of this work is to address this by studying the soot temperature of microgravity flames spreading over a thin solid in microgravity. The ex-periments presented here were performed as part of the NASA project Saffire IV, conducted in orbit on board the Cygnus resupply vehicle before it re-entered the Earth's atmosphere. The fuel considered is a thin fabric made of cotton and fiberglass (Sibal) exposed to a forced flow of 20 cm/s in a concurrent flow configuration. Reconstruction of the flame temperature fields is extracted from two color broadband emission pyrometry (B2CP) as the flame propagates over the solid fuel. A methodology, relevant assumptions and its applicability to other microgravity experiments are discussed here. The data obtained shows that the technique provides an acceptable average temperature around similar to 1300 K, which remains relatively constant during the spread with an error value smaller than 117 K. The data presented in this work provides a methodology that could be applied to other microgravity experiments to be performed by NASA. It is expected that the results will provide insight for what is to be expected in different conditions relevant for fire safety in future space facilities. (c) 2022 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1540-7489 ISBN Medium
Area Expedition Conference
Notes WOS:001058486000001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1879
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Author (down) Thomsen, M.; Cruz, J.J.; Escudero, F.; Fernandez-Pello, C.; Fuentes, A.
Title Sooting behavior on a spreading flame over PMMA rods under different oxygen concentrations Type
Year 2023 Publication Fire Safety Journal Abbreviated Journal Fire Saf. J.
Volume 141 Issue Pages 103967
Keywords Diffusion flame; Solid fuel burning; Flame spread; Line of sight attenuation; Axisymmetric flame
Abstract The flame spread process over the surface of a solid combustible material is highly influenced by the radiative feedback from the flame, and the conditions under which the process takes place. Soot particles generated during the burn are a big contributor to flame radiation and can play a critical role in the radiative exchange between the flame and the solid. Thus, increased knowledge of the soot production processes involved in the spread of a flame can further promote the understanding of growth and development of fires. The main purpose of this work is to study the effect of oxygen concentration on the sooting behavior of cylindrical samples of polymethyl-methacrylate (PMMA) in an opposed flow configuration. Measured data shows that during downward/opposed flame spread the mass burning rate and soot volume fractions increase with higher oxygen concentrations. The data presented is correlated using a scaling analysis that provides correlations for the maximum soot volume fraction, and the maximum integrated soot volume fraction as a function of the oxygen concentration using similar residence times to establish comparable conditions. The data shows the correlations introduced here provide useful information of the sooting behavior of spreading flames in environments of varied oxygen concentrations that could be used to guide potential fire safety applications.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0379-7112 ISBN Medium
Area Expedition Conference
Notes WOS:001083427400001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1893
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Author (down) Reszka, P.; Cruz, J.J.; Valdivia, J.; Gonzalez, F.; Rivera, J.; Carvajal, C.; Fuentes, A.
Title Ignition delay times of live and dead pinus radiata needles Type
Year 2020 Publication Fire Safety Journal Abbreviated Journal Fire Saf. J.
Volume 112 Issue Pages 7 pp
Keywords Leaf senescence; Photosynthetic pigments; Critical heat flux; Moisture content; Wildland fire
Abstract There are still many open questions related to the fire behavior of live and dead wildland fuels and their senescence process. We have physically and biochemically studied live and dead pinus radiata needles, their aging process, and their fire behavior using a systematic aging procedure which allows to characterize the evolution of the fuel moisture content and the photosynthetic pigments over time, and to determine the period of time after sample collection in which specimens can be considered to be alive. Results show that pine needles stay alive for up to 12 h after collection if they remain attached to the twigs. The influence of senescence on spontaneous ignition was tested on two bench-scale devices, the I-FIT and the SCALA, under discontinuous and continuous configurations, respectively. Live pine needles showed larger critical heat fluxes than dead needles, while dead and re-hydrated samples have increased critical heat fluxes for greater moisture contents. Experimental results were interpreted with thermal models based on a two-phase description of the fuel layer. We established a correlation of the form 1/t(ig)proportional to q(inc)" for both ignition configurations, which is adequate for engineering applications and allows the estimation of effective properties for wildland fuel beds.
Address [Reszka, P.; Valdivia, J.] Univ Adolfo Ibanez, Fac Engn & Sci, Santiago, Chile, Email: andres.fuentes@usm.cl
Corporate Author Thesis
Publisher Elsevier Sci Ltd Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0379-7112 ISBN Medium
Area Expedition Conference
Notes WOS:000527282900005 Approved
Call Number UAI @ eduardo.moreno @ Serial 1146
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Author (down) Cruz, J.J.; Escudero, F.; Alvarez, E.; da Silva, L.F.F.; Carvajal, G.; Thomsen, M.; Fuentes, A.
Title Three-wavelength broadband soot pyrometry technique for axisymmetric flames Type
Year 2021 Publication Optics Letters Abbreviated Journal Opt. Lett.
Volume 46 Issue 11 Pages 2654-2657
Keywords VOLUME FRACTION; DIFFUSION FLAMES; TEMPERATURE; ABSORPTION; ETHYLENE
Abstract Soot temperature measurements in laminar flames are often performed through two-color broadband emission pyrometry (BEMI) or modulated absorption/emission (BMAE) techniques, using models to relate the ratio between flame intensities at two different wavelengths with soot temperature. To benefit from wider spectral range and increase the accuracy of experimental estimation of soot temperature, this work proposes a new approach that uses three-color broadband images captured with a basic color camera. The methodology is first validated through simulations using numerically generated flames from the CoFlame code and then used to retrieve soot temperature in an experimental campaign. The experimental results show that using three-color and BEMI provides smoother reconstruction of soot temperature than two-color and BMAE when small disturbances exist in the measured signals due to a reduced experimental noise effect. A sensitivity analysis shows that the retrieved temperature from three-color BEMI is more resilient to variations on the ratio of measured signals than BMAE, which is confirmed by an error propagation analysis based on a Monte Carlo approach.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0146-9592 ISBN Medium
Area Expedition Conference
Notes WOS:000658132700025 Approved
Call Number UAI @ alexi.delcanto @ Serial 1413
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