Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples

Flame spread in the kinetic regime and eventual extinction have been studied for more than four decades for the implications on fire safety and flame instabilities. It is well known that the ratio between the residence time and the combustion time at the leading edge, the so called Damköhler number,...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Luca CARMIGNANI, Francesco LOTTI, Subrata BHATTACHARJEE
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2016
Materias:	flame spread flame extinction solid fuel pmma experiments Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/e03116ade4694554b8beded828a0352c
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:e03116ade4694554b8beded828a0352c
record_format	dspace
spelling	oai:doaj.org-article:e03116ade4694554b8beded828a0352c2021-11-26T06:58:33ZComparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples2187-974510.1299/mej.16-00277https://doaj.org/article/e03116ade4694554b8beded828a0352c2016-08-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/3/6/3_16-00277/_pdf/-char/enhttps://doaj.org/toc/2187-9745Flame spread in the kinetic regime and eventual extinction have been studied for more than four decades for the implications on fire safety and flame instabilities. It is well known that the ratio between the residence time and the combustion time at the leading edge, the so called Damköhler number, plays a fundamental role in the blow-off extinction of a spreading flame. However, the role of the boundary layer, which may significantly affect the residence time at the flame leading edge, on the blow-off extinction has not been thoroughly studied. In this work we present new experimental data on blow-off extinction of PMMA (polymethyl methacrylate) fuels and establish an empirical relation between the boundary layer development length and the extinction flow velocity. Using a vertical wind tunnel it has been possible to carry on a large number of experiments over thin PMMA samples, for an opposed flow velocity range from 0 cm/s up to 100 cm/s. Furthermore, it was possible to rotate the wind tunnel to obtain results with a horizontal configuration, reducing the effect of buoyancy on the flame spread. The experimental data reveal that the extinction length, the distance from the sample leading edge at which the blow-off extinction occurs, is directly related to the opposing flow velocity. Using a simplified scale analysis previously proved to be reliable, the blow-off extinction appeared to occur at a constant effective velocity (defined inside of the boundary layer). This conclusion can have important implications in the definition of the kinetic regime and the quantification of an extinction limit for thin fuels.Luca CARMIGNANIFrancesco LOTTISubrata BHATTACHARJEEThe Japan Society of Mechanical Engineersarticleflame spreadflame extinctionsolid fuelpmma experimentsMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 3, Iss 6, Pp 16-00277-16-00277 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	flame spread flame extinction solid fuel pmma experiments Mechanical engineering and machinery TJ1-1570
spellingShingle	flame spread flame extinction solid fuel pmma experiments Mechanical engineering and machinery TJ1-1570 Luca CARMIGNANI Francesco LOTTI Subrata BHATTACHARJEE Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples
description	Flame spread in the kinetic regime and eventual extinction have been studied for more than four decades for the implications on fire safety and flame instabilities. It is well known that the ratio between the residence time and the combustion time at the leading edge, the so called Damköhler number, plays a fundamental role in the blow-off extinction of a spreading flame. However, the role of the boundary layer, which may significantly affect the residence time at the flame leading edge, on the blow-off extinction has not been thoroughly studied. In this work we present new experimental data on blow-off extinction of PMMA (polymethyl methacrylate) fuels and establish an empirical relation between the boundary layer development length and the extinction flow velocity. Using a vertical wind tunnel it has been possible to carry on a large number of experiments over thin PMMA samples, for an opposed flow velocity range from 0 cm/s up to 100 cm/s. Furthermore, it was possible to rotate the wind tunnel to obtain results with a horizontal configuration, reducing the effect of buoyancy on the flame spread. The experimental data reveal that the extinction length, the distance from the sample leading edge at which the blow-off extinction occurs, is directly related to the opposing flow velocity. Using a simplified scale analysis previously proved to be reliable, the blow-off extinction appeared to occur at a constant effective velocity (defined inside of the boundary layer). This conclusion can have important implications in the definition of the kinetic regime and the quantification of an extinction limit for thin fuels.
format	article
author	Luca CARMIGNANI Francesco LOTTI Subrata BHATTACHARJEE
author_facet	Luca CARMIGNANI Francesco LOTTI Subrata BHATTACHARJEE
author_sort	Luca CARMIGNANI
title	Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples
title_short	Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples
title_full	Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples
title_fullStr	Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples
title_full_unstemmed	Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples
title_sort	comparison of flame spread and blow-off extinction over vertical and horizontal pmma samples
publisher	The Japan Society of Mechanical Engineers
publishDate	2016
url	https://doaj.org/article/e03116ade4694554b8beded828a0352c
work_keys_str_mv	AT lucacarmignani comparisonofflamespreadandblowoffextinctionoververticalandhorizontalpmmasamples AT francescolotti comparisonofflamespreadandblowoffextinctionoververticalandhorizontalpmmasamples AT subratabhattacharjee comparisonofflamespreadandblowoffextinctionoververticalandhorizontalpmmasamples
_version_	1718409749398028288

Comparison of flame spread and blow-off extinction over vertical and horizontal PMMA samples

Ejemplares similares