Scaling and instability analyses on flame spread over liquids

Takahashi, Kozue; Ito, Akihiko; Kudo, Yuji; Konishi, Tadashi; Saito, Kozo

doi:10.1016/j.proci.2004.08.246

Cited by 23 publications

(24 citation statements)

References 11 publications

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“…Therefore, it is necessary to study the phenomena and mechanism of flame spread over floating oil. Flame spread over liquid fuel has been a hot topic of combustion theory and fire safety science since the 1960s and has been investigated experimentally and numerically [1][2][3][4][5][6][7][8][9]. Such researches have mainly focused on the effects of parameters such as the initial fuel temperature and tray width on the rate of flame spread and on the qualitative analysis of surface convection.…”

mentioning

confidence: 99%

Experimental study of flame spread over oil floating on water

Guo

Zhou

et al. 2012

Chin. Sci. Bull.

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The phenomena and mechanism of flame spread over oil floating on water were studied using temperature measurements made by fine thermocouples and an infrared camera, schlieren images of surface convection and video recordings of flame spread. The experimental results reveal that the floating-oil depth greatly affects the average rate of flame spread and average flame pulsation wavelength. The surface tension effect is the main cause of surface convection, which controls flame spread. Momentum loss and heat loss from forward-flowing hot oil to water play an important role in retarding flame spread for oil thicknesses less than about 8 mm. With the development of the exploitation of offshore oil and marine transportation, there have been frequent fires resulting from oil spills. Because of the quick diffusion of oil leaked on water and the fast spread of flames over an oil surface, such fires usually have catastrophic consequences. Although flame spread is only a short process during a fire, it determines the direction of flame spread and the best time to put out fires. On the other hand, controlled combustion is an important way to clean up floating oil, but the precondition is that the flame can spread over the floating oil. Therefore, it is necessary to study the phenomena and mechanism of flame spread over floating oil. Flame spread over liquid fuel has been a hot topic of combustion theory and fire safety science since the 1960s and has been investigated experimentally and numerically [1][2][3][4][5][6][7][8][9]. Such researches have mainly focused on the effects of parameters such as the initial fuel temperature and tray width on the rate of flame spread and on the qualitative analysis of surface convection. However, little has been done to study flame spread over floating oil, which has the distinguishing characteristics that the floating oil is usually thin and water greatly affects the flame-spread phenomena. Mackinven et al.[10] experimented with decane floating on water and found that the average rate of flame spread increased with an increase in fuel thickness. Neil et al. [11] confirmed that fuel thickness has a large effect on the rate of flame spread. However, the researchers [10,11] obtained only qualitative results, and the reason why fuel thickness affects the phenomena of flame spread remains unclear till now. In the present study, the flame spread over different thicknesses of aviation kerosene (with a flash point of about 66C) floating on water was investigated simultaneously employing a schlieren system, an infrared camera, fine thermocouples and charge-coupled device (CCD) cameras. The paper presents the variation in the average rate of flame spread with floating oil thickness, gives reasons why the oil thickness affects the flame spread rate and presents the mechanism of flame spread.

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confidence: 99%

Experimental study of flame spread over oil floating on water

Guo

Zhou

et al. 2012

Chin. Sci. Bull.

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“…The temperature coefficient of surface tension and other physical properties are treated as constants. Our instability analysis is based on the previous study [31][32][33][34]. A schematic of subsurface layer flow is shown in Figure 3.…”

Section: Basic Equationmentioning

confidence: 99%

“…The flame spread rate was measured from the recorded digital image. Temperature structures created in the liquid were visualized by our specially designed high sensitivity shadowgraph (HSSG) [34], which measures the refraction of a beam when it passes across the liquid. The 50 mW He-Ne laser beam passes through a tracing paper and is changed into scattered light in order to remove any distortion from the shadowgraph.…”

Section: Normal Gravity Experimentsmentioning

confidence: 99%

“…To benefit from all these experimental and numerical studies both under normal gravity and microgravity and to update the theory of flame spread over liquids formulated International Journal of Chemical Engineering 3 by Williams [30], we conducted stability based on the basic reference [31] and scaling analyses on these results in the hope of finding a unified theoretical framework within which to relate them [32][33][34]. Our instability analysis was focused on the liquid subsurface layer ahead of a flame's leading edge, where a surface wave is initiated and a cold temperature valley is created.…”

Section: Introductionmentioning

confidence: 99%

“…The characteristic length scale ratio, h T /L consists of a characteristic thermal fluid length in the liquid surface, and a subsurface liquid circulation (or thermal structure) depth both created by the spreading flame. Figure 2 shows thermal and flow characteristic depths h T and h F , and thermal characteristic length L, determined from a shadowgraph image and a particle-track laser-sheet image [34].…”

Section: Introductionmentioning

confidence: 99%

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Scaling Analysis on Pulsating Flame Spread over Liquids

Takahashi

Ito

Kudo

et al. 2008

International Journal of Chemical Engineering

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Scaling analyses based on subsurface layer instability were performed to explore the role of three independent (surface tension, gravity, and viscosity) influences on the mechanism of pulsating flame spread under normal and microgravity conditions. These three influences form two independent pi-numbers: the Marangoni (Ma) number and Grashof (Gr) number, which include the characteristic length scale ratio (depth of subsurface circulation)/(horizontal length of preheated liquid surface). The Prandtl (Pr) number was introduced to compensate for the different thermal diffusivity and kinematic viscosity of different liquids. Also a nondimensional flame spread rate, V/V D (= Vδ/D, where δ is the quenching distance and D is the diffusivity of fuel vapor) was introduced. Using these nondimensional parameters, the flame spread mechanism was divided into two separate regimes: for the shallow liquid pool the nondimensional flame spread rate was correlated with {Gr 0.2 /(Ma·Pr)} 1.0 , while for the deep liquid pool it was correlated with {Gr 0.2 /(Ma·Pr)} 1.5 .

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Inhibition behavior and heat transfer of flame spread over liquid fuel with the influence of a step obstacle in the gas phase

Yang,

Hu,

et al. 2023

Process Safety Progress

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The transportation of oil is an important aspect of chemical process safety. In the accidental leakage of oil and related products, the flame spread occurs occasionally when the liquid fuel is activated by a pilot flame. In the potential application of fire prevention, a step obstacle placed above the oil ditch may effectively hinder the flame spread. The effectiveness of the usage of a step obstacle depends on the size of the obstacle and the heat exchange mechanism. Therefore, the investigation of inhibition behavior and heat transfer of liquid flame spread with gas step obstacle is performed. The hot fluids flow inside the channel to carry out the convection heat to the initial cold oils on the opposite of the gas step obstacle. The flame configuration is blocked behind the step obstacle. The flame spread behaviors including flame morphology, inhibition time, and air entrainment are characterized and analyzed. The heat flows of flame radiation and liquid‐phase convection are theoretically calculated, and the primary heat transfer mechanism is determined. This work is helpful for the development of fire safety technology and the establishment of standard specifications for oil transportation.

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Scaling and instability analyses on flame spread over liquids

Cited by 23 publications

References 11 publications

Experimental study of flame spread over oil floating on water

Experimental study of flame spread over oil floating on water

Scaling Analysis on Pulsating Flame Spread over Liquids

Inhibition behavior and heat transfer of flame spread over liquid fuel with the influence of a step obstacle in the gas phase

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