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Author Thomsen, M.; Fernandez-Pello, A.C.; Williams, F.A.
Title (up) On the Growth of Wildland Fires from a Small Ignition Source Type
Year 2023 Publication Combustion Science and Technology Abbreviated Journal Combust. Sci. Technol.
Volume Early Access Issue Pages
Keywords Wildfire; spot ignition; fire growth; rate of spread; fire model
Abstract Wildland and Wildland-Urban-Interface (WUI) fires are an important problem that may have major consequences in terms of safety, air quality, and damage to buildings, infrastructure, and the ecosystem. It is expected that with climate change, the wildland fire and WUI fire problem will only intensify. Wildland fires are often initiated by small ignition sources caused either by human intervention (hot metal fragments or burning biomass) or by natural events (lighting or sun heating). Once the wildfire or structural fire has been ignited and grows, it can spread rapidly through ember spotting, where pieces of burning materials are lifted by the plume of the fire and then transported forward by the wind, landing where they can start spot fires downwind. The ignition mechanisms for all of these fires have the common characteristic of a small and localized area of origin, with the subsequent spread of the fire to wider and larger areas. Because of the three-dimensional characteristics of this type of propagating fire, its rate of spread has an initial acceleration phase leading to an equilibrium rate of spread when the fire reaches a certain size, which is referred to as a “line-fire” type of spread. Most of the studies on wildland fire propagation have been conducted with line fires and have been concerned with characterizing the equilibrium rate of spread rather than the initial spread from a small ignition source. In this paper, some of the studies conducted to date on the subject of wildland fire growth from a small ignition source, and the physics supporting the mathematical expressions that are used to describe the growth of the fire are discussed. An attempt is also made to provide support for these works through a more fundamental approach to model the problem.
Address
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 0010-2202 ISBN Medium
Area Expedition Conference
Notes WOS:001034393700001 Approved
Call Number UAI @ alexi.delcanto @ Serial 1845
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Author Hernandez, N.; Fuentes, A.; Reszka, P.; Fernandez-Pello, A.C.
Title (up) Piloted ignition delay times on optically thin PMMA cylinders Type
Year 2019 Publication Proceedings Of The Combustion Institute Abbreviated Journal Proc. Combust. Inst.
Volume 37 Issue 3 Pages 3993-4000
Keywords Integral heat equation; P-1 radiation model; Analytical model; Critical heat flux; Optically thin solids
Abstract The theory to predict ignition of solid fuels exposed to incident radiant heat fluxes has permitted to obtain simple correlations of the ignition delay time with the incident heat flux which are useful in practical engineering applications. However, the theory was developed under the assumption that radiation does not penetrate into the solid phase. In the case of semi-transparent solids, where the penetration of radiation plays an important role in the heating and subsequent ignition of the fuel, the predictions of the classical ignition theory are not applicable. A new theory for the piloted ignition of optically thin cylindrical fuels has been developed. The theory uses an integral method and an approximation of the radiative transfer equation within the solid to predict the heating of an inert solid. An exact and an approximate analytical solution are obtained. The predictions are compared with piloted ignition experiments of clear PMMA cylinders. The results indicate that for opticallythin media, the heating and ignition are not sensible to the thermal conductivity of the solid, they are highly dependent on the in-depth absorption coefficient. Using the approximate solution, the correlation 1/t(ig) proportional to (q)over dot(inc)'' was established. This correlation is adequate for engineering applications, and allows the estimation of effective properties of the solid fuel. The form of the correlation that was obtained is due to the integral method used in the solution of the heat equation, and does not imply that the semi-transparent solid behaves like a thermally thin material. The approximate solution presented in this article constitutes a useful tool for pencil-and-paper calculations and is an advancement in the understanding of solid-phase ignition processes. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
Address [Hernandez, N.; Fuentes, A.] Univ Tecn Feder Santa Maria, Dept Ind, Valparaiso, Chile, Email: pedro.reszka@uai.cl
Corporate Author Thesis
Publisher Elsevier Science Inc Place of Publication Editor
Language English 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:000456628600154 Approved
Call Number UAI @ eduardo.moreno @ Serial 973
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