Embedded flame heat flux method for simulation of quasi-steady state vertical flame spread

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Li, Kaiyuan
dc.contributor.author Hostikka, Simo
dc.date.accessioned 2019-02-25T08:40:29Z
dc.date.available 2019-02-25T08:40:29Z
dc.date.issued 2019-03-01
dc.identifier.citation Li , K & Hostikka , S 2019 , ' Embedded flame heat flux method for simulation of quasi-steady state vertical flame spread ' Fire Safety Journal , vol. 104 , pp. 117-129 . https://doi.org/10.1016/j.firesaf.2019.01.011 en
dc.identifier.issn 0379-7112
dc.identifier.other PURE UUID: 0b192017-9ae6-4f34-89a8-2939dd5faf0a
dc.identifier.other PURE ITEMURL: https://research.aalto.fi/en/publications/embedded-flame-heat-flux-method-for-simulation-of-quasisteady-state-vertical-flame-spread(0b192017-9ae6-4f34-89a8-2939dd5faf0a).html
dc.identifier.other PURE LINK: http://www.scopus.com/inward/record.url?scp=85061330878&partnerID=8YFLogxK
dc.identifier.other PURE FILEURL: https://research.aalto.fi/files/31848136/Li_Hostikka_FSJ_2019_Preprint.pdf
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/36641
dc.description.abstract Flame spread has been an important but unsolved problem for decades as its numerical solution requires simultaneous accurate solutions in solid and gas phases. In the current study, a numerical model involving gas-phase Large Eddy Simulation (LES) and comprehensive solid pyrolysis model was built as the first step of the research with a sufficient resolution for reproducing the flame spread rates in a set of upward flame spread experiments on birch rods. In the current conditions, the flame spread is dominated by the convective heat transfer and the predicted spread rates are thus sensitive to the heat transfer model. The convective and radiative heat fluxes during steady state were then extracted from the model results and used to improve the accuracy of coarse mesh simulations by embedding them as thermal boundary conditions for the solid phase. Three alternative techniques were investigated: Normalizing the heat flux profile with the length of the pyrolysis zone (fully coupled technique) resulted in accurate spread rates only if the initial pyrolysis zone was specified precisely and the gas phase resolution remained sufficiently fine. In the second, uncoupled technique, the length of the pyrolysis zone was fixed. Accurate steady state flame spread rates were then achieved regardless of the mesh resolution and the initial length of the pyrolysis zone. Finally, the most promising technique involved a normalized heat flux profile within the pyrolysis zone and a generalized heat flux function within the preheating zone. Correct spread rates were achieved with up to ten times increase in cell size regardless of the initial pyrolysis zone properties. en
dc.format.extent 117-129
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher ELSEVIER SCI LTD
dc.relation.ispartofseries Fire Safety Journal en
dc.relation.ispartofseries Volume 104 en
dc.rights openAccess en
dc.subject.other 113 Computer and information sciences en
dc.title Embedded flame heat flux method for simulation of quasi-steady state vertical flame spread en
dc.type A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä fi
dc.description.version Peer reviewed en
dc.contributor.department Wuhan University of Technology
dc.contributor.department Department of Civil Engineering
dc.subject.keyword Flame spread
dc.subject.keyword Wood
dc.subject.keyword Pyrolysis
dc.subject.keyword Numerical modelling
dc.subject.keyword Heat flux
dc.subject.keyword LES
dc.subject.keyword 113 Computer and information sciences
dc.identifier.urn URN:NBN:fi:aalto-201902251798
dc.identifier.doi 10.1016/j.firesaf.2019.01.011
dc.date.embargo info:eu-repo/date/embargoEnd/2019-03-01

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