Correlations for Evaluation of Flame Spread over an Inclined Fuel Surface

Huang, Xinyan; Gollner, Michael J.

doi:10.3801/iafss.fss.11-222

Cited by 37 publications

(30 citation statements)

References 33 publications

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“…The flame thickness L is defined as the vertical distance between the flame sheet and the fuel surface, 35,36 which is one of the most important parameters characterizing the flame spread behavior. Figure 6 shows the time evolutions of flame thickness for 4 and 8 cm wide samples, respectively.…”

Section: Resultsmentioning

confidence: 99%

Experimental study of the width effects on self-induced buoyant blow off in upward flame spread over thin fabric fuels

Zhu

Gao

Chai

et al. 2019

Textile Research Journal

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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.

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Section: Resultsmentioning

confidence: 99%

Experimental study of the width effects on self-induced buoyant blow off in upward flame spread over thin fabric fuels

Zhu

Gao

Chai

et al. 2019

Textile Research Journal

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“…9,35,36 For thermally thin materials, the temperature distribution across the thickness is essentially uniform and the conduction heat transfer can be negligible in upward spreading. 10,35,37 Therefore, q net can be expressed as 38…”

Section: Temperature Field and Heat Transfer Analysismentioning

confidence: 99%

“…The parameter of the flame standoff distance can be used to characterize the radiation heat transfer to the virgin fuel. 9,10 The variation with time of the flame standoff distance for the 04# test samples is plotted for a representative case, which is shown in Figure 11. Notably, the flame standoff distance first increases rapidly and then shows a slow increase until the flame front reaches the top of the test samples, which also suggests that the upward flame spread does not achieve a completely steady state.…”

Section: Temperature Field and Heat Transfer Analysismentioning

confidence: 99%

“…Pizzo et al 8 established a transient pyrolysis model based on the modified mass transfer number to predict the flame spread rate over inclined PMMA. Gollner et al, 9 Huang and Gollner 10 and Gao et al 11 investigated the upward flame spread characteristics over inclined solid fuel surfaces and proposed that the flame tilt angle and flame standoff distance could qualitatively describe the heat flux profiles in the preheating region. Moreover, the effects of ambient pressure, [12][13][14] oxygen concentration, [15][16][17] moisture content, [18][19][20] external flow velocity [21][22][23][24] and different configurations [25][26][27][28] on flame spread over solid fuel surfaces have been widely investigated by experimental measures and theoretical analyses.…”

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confidence: 99%

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Effects of porosity and area density on upward flame spread characteristics over thin flax fabric

Gao

Hui

Zhang

et al. 2020

Textile Research Journal

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Few investigations have systematically addressed the porosity effects of upward flame spread over fabric fuels, although the porosity is a special property for fabric fuels. The present paper studies the porosity and area density effects on upward flame spreading using 160.0 cm tall and 8.0 cm wide flax fabric samples with various porosities and area densities. The flame shape, flame length, flame spread rate, ignition time, standoff distance and surface temperature distribution are obtained and analyzed. The major findings are summarized as follows: as the porosity increases and corresponding area density declines, the flame spread rate and flame length increase, whereas the ignition time decreases, which is because the oxygen can reach the fuel surface in the pyrolysis region more easily and, subsequently, the heat flux received by the virgin fuels increases. The two parameters of flame standoff distance and surface temperature in the preheating region can be applied to characterize the heat flux received by the virgin fuels. Generally, when the porosity increases and the corresponding area density decreases, the flame standoff distance and the surface temperature at the same distance from pyrolysis front increase, which reveals that the heat flux received by the virgin surface increases.

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“…Later, an important early semi-empirical model of upward flame spread with an orientation effect was proposed by Quintiere in 2001 using a polyethylene terephthalate (PET) board [14]. In addition, related works were conducted continuously by Gollner et al [15,16] in recent years. However, it will be a different story when both effects of inclination and pressure are combined, complexly impacting the entire spreading process.…”

Section: Introductionmentioning

confidence: 99%

Influences of Sub-Atmospheric Pressure on Upward Flame Spread over Flexible Polyurethane Foam Board with Multiple Inclinations

Zeng

et al. 2020

Applied Sciences

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Fire propagation and burning characteristics of upward flame spread over flexible polyurethane (FPU) foam board were investigated under coupling effects of pressure and orientation. As a further comparative research of our previous work, three pressures (70, 85 and 100 kPa) and four fuel surface inclination angles (0°, 30°, 60°, 90°) were applied, respectively, as before, to study the variation of typical parameters including flame spread rate (FSR), burning rate, heat transfer components, flame length, etc. First, a phenomenological interpretation was taken to show the special spreading process with melting flow combustion and flash burning observed. Second, an overall theoretical analysis was proposed to reveal the individual or coupling effects of pressure and inclined burning surface on spreading behavior. A semi-quantitative correlation was developed and formulated to show the tendency of FSR as a function of pressure, inclination and other burning parameters, which was validated by data in paper. Meanwhile, comparison of detailed differences between upward and downward spread was conducted to give a full insight on FPU fire development. At last, comprehensive discussions of coupling effects on variation of spreading characteristics and heat transfer mechanisms were performed based on fire dynamics.

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Correlations for Evaluation of Flame Spread over an Inclined Fuel Surface

Cited by 37 publications

References 33 publications

Experimental study of the width effects on self-induced buoyant blow off in upward flame spread over thin fabric fuels

Experimental study of the width effects on self-induced buoyant blow off in upward flame spread over thin fabric fuels

Effects of porosity and area density on upward flame spread characteristics over thin flax fabric

Influences of Sub-Atmospheric Pressure on Upward Flame Spread over Flexible Polyurethane Foam Board with Multiple Inclinations

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