In this paper, a series of upward flame spreading experiments were conducted on thin flax fabric with various widths ranging from 3.0 to 8.0 cm and length of 1.6 m. Symmetric ignition at the entire bottom edge of samples led to two-sided upward flame growth initially. A very interesting behavior of flame blown off was observed in upward flame spreading and an explanation was provided based on the increased buoyancy-induced velocity at the flame base. When the sample width is 6 cm or less, the flame length increases to a critical value and, correspondingly, the buoyancy-induced velocity reaches the blow off velocity, which results in a flame being blown off on one side. The remaining flame on the other side would shrink in length and propagate to the end of the sample with an asymptotically constant length and steady spread rate. For samples wider than 6 cm, the two-sided flame continues to spread to the end of samples and the self-induced blow off phenomenon is not observed. Moreover, the width effects on the flame height, flame thickness and flame spread rate are analyzed and explained in this paper. The results of this study may help advance better understanding of flame blow off behaviors over solid surfaces and have implications concerning fire control of flame spread over solid fuels.
Markstein GH and de Ris J. Upward fire spread over textiles. In: Barnes HG (ed.) Fourteenth Symposium on Combustion. Pennsylvania State University, 1973, 14, pp. 1085–1097.
2.
DrysdaleDDMacmillanAJR. Flame spread on inclined surfaces. Fire Safe J1992; 18: 245–254.
3.
QuintiereJG. The effects of angular orientation on flame spread over thin materials. Fire Safe J2001; 36: 291–312.
4.
TsaiKCDrysdaleD. Flame height correlation and upward flame spread modelling. Fire Mater2002; 26: 279–287.
5.
RangwalaASBuckleySGToreroJL. Upward flame spread on a vertically oriented fuel surface: the effect of finite width. Proc Combust Inst2007; 31: 2607–2615.
6.
TsaiKC. Width effect on upward flame spread. Fire Safe J2009; 44: 962–967.
7.
TsaiKC. Influence of sidewalls on width effects of upward flame spread. Fire Safe J2011; 46: 294–304.
8.
TsaiKCWanF. Upward flame spread: the width effect. Fire Safe Sci2005; 8: 409–419.
9.
PizzoYConsalviJLQuerreP, et al.Width effects on the early stage of upward flame spread over PMMA slabs: experimental observations. Fire Safe J2009; 44: 407–414.
AnWGHuangXJWangQS, et al.Effects of sample width and inclined angle on flame spread across expanded polystyrene surface in plateau and plain environments. J Thermoplast Compos Mater2013; 28: 111–127.
12.
ZhaoHZZhangYMWangYM, et al.Width effect on a vertical RPU flame spread with a middle linear ignition. Heat Transf Res2015; 46: 673–687.
13.
JiangLHeJJSunJH. Sample width and thickness effects on upward flame spread over PMMA surface. J Hazard Mater2018; 342: 114–120.
14.
SatoKMikiKHiranoT. Flame spread over paper in an air stream with a velocity change. J Heat Transf1984; 106: 707–712.
15.
FerkulPVT'IenJS. A model of low-speed concurrent flow flame spread over a thin fuel. Combust Sci Technol1994; 99: 345–370.
16.
ItoAKudoYOyamaH. Propagation and extinction mechanisms of opposed-flow flame spread over PMMA for different sample orientations. Combust Flame2005; 142: 428–437.
17.
ZhaoXYT’ienJS. A three-dimensional transient model for flame growth and extinction in concurrent flows. Combust Flame2015; 162: 1829–1839.
18.
HuLHLuYYoshiokaK, et al.Limiting oxygen concentration for extinction of upward spreading flames over inclined thin polyethylene-insulated NiCr electrical wires with opposed-flow under normal- and micro-gravity. Proc Combust Inst2017; 36: 3045–3053.
19.
JohnstonMCT'ienJSMuffDE, et al.Self induced buoyant blow off in upward flame spread on thin solid fuels. Fire Safe J2015; 71: 279–286.
20.
ZhangYSunJHHuangXJ, et al.Heat transfer mechanisms in horizontal flame spread over wood and extruded polystyrene surfaces. Int J Heat Mass Transf2013; 61: 28–34.
21.
ZhouYXiaoHHSunJH, et al.Experimental study of horizontal flame spread over rigid polyurethane foam on a plateau: effects of sample width and ambient pressure. Fire Mater2015; 39: 127–138.
22.
Comas B and Pujol T. Flame front speed and onset of instability in the burning of inclined thin solid fuel samples. Phys Rev E 2013; 88: 063019.
23.
UrbasJParkerWJLuebbersGE. Surface temperature measurements on burning materials using an infrared pyrometer: accounting for emissivity and reflection of external radiation. Fire Mater2004; 28: 33–53.
24.
ChengQIshidaHSaitoK. Upward flame spread along PMMA vertical corner walls Part II: mechanism of “M” shape pyrolysis front. Combust Flame1994; 99: 331–338.
25.
Miller CH and Gollner MJ. Upward flame spread over discrete fuels. Fire Safety Journal 2015; 77: 36–45.
26.
ZhuHZhuGQGaoYJ, et al.Experimental studies on the effects of spacing on upward flame spread over thin PMMA. Fire Technol2017; 53: 673–693.
27.
ArakawaASaitoKGruverWA. Automated infrared imaging temperature measurement with application to upward flame spread studies. Part I. Combust Flame1993; 92: 222–230.
28.
LiangCJChengXDYangH, et al.Experimental study of vertically upward flame spread over polymethyl methacrylate slabs at different altitudes. Fire Mater2016; 40: 472–481.
29.
Leon S and Drake Jr. The horizontal flame-propagation rate of undyed cotton fabrics. Text Res J 1976; 46: 238–246.
30.
McAllisterS. Critical mass flux for flaming ignition of wet wood. Fire Safe J2013; 61: 200–206.
31.
SafronavaNLyonRECrowleyS, et al.Effect of moisture on ignition time of polymers. Fire Technol2014; 51: 1093–1112.
32.
WongchaiPTachajapongW. Effects of moisture content in para rubber leaf litter on critical mass flux and piloted ignition time. Energy Procedia2015; 79: 448–452.
33.
GaoYJZhuGQZhuH, et al.Experimental analysis of critical acceleration condition for two-sided upward flame spread over inclined thin fuel surfaces. Fire Technol2019; 55: 755–771.
34.
WilliamsFA. Combustion theory, Menlo Park, CA: Benjamin Cummings Publishing Company, 1985.
35.
GollnerMJHuangXCobianJ, et al.Experimental study of upward flame spread of an inclined fuel surface. Proc Combust Inst2013; 34: 2531–2538.
36.
HuangXGollnerM. Correlations for evaluation of flame spread over an inclined fuel surface. Fire Safe Sci2014; 11: 222–233.
37.
ZhangYHuangXJWangQS, et al.Experimental study on the characteristics of horizontal flame spread over XPS surface on plateau. J Hazard Mater2011; 189: 34–39.
38.
ThomasPHWebsterCT. Some experiments on the burning of fabrics and the height of buoyant diffusion flames. Fire Safe Sci1960; 420: 1–1.
39.
GaoYJZhuGQZhuH, et al.Experimental study of the non-monotonous moisture effect on upward flame spread over cotton fabric. Text Res J2018; 88: 2379–2394.
40.
KumarA. A comparison of extinction limits and spreading rates in opposed and concurrent spreading flames over thin solids. Combust Flame2003; 132: 667–677.
