Effect of flow circulation on combustion dynamics of fire whirl

Zhou, Kuibin; Liu, Naian; Lozano, Jesse S.; Shan, Yanlong; Yao, Bin; Satoh, Kohyu

doi:10.1016/j.proci.2012.06.053

Cited by 66 publications

(36 citation statements)

References 18 publications

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“…As the circulation strength increases, the spiraling flame tilts and eventually elongates so that its axis coincides with the central axis as a sustainable vertical column of whirling flame (Byram & Martin 1962, 1970. This delivers a quasi-steady, on-source fire whirl that has been studied extensively (Satoh & Yang 1996, Satoh et al 1997, Hassan et al 2005, Hayashi et al 2011, Lei et al 2011, Zhou et al 2013, Dobashi et al 2015, Wang et al 2016, Xiao et al 2016. Square enclosures with tangential slits have also been used ( Figure 4b); however, they may introduce redundant eddies into the system due to the recirculation zones at the corners .…”

Section: Enclosed Configurationsmentioning

confidence: 99%

“…The maximum recorded temperatures occurred near/within the flame sheet, where this value was 1.6 times the centerline temperature (T max − T ∞ ≈ 1.6T r=0 ). This implies that the fire whirl has a fuel-rich core with no active combustion reaction (Wang et al 2015), which significantly influences the radial temperature distribution throughout the continuous flame region (Zhou et al 2013). The radius of this core is defined as the location where T = T max (Emmons & Ying 1967).…”

Section: Thermal Compositionmentioning

confidence: 99%

“…The results are consistent with Emori & Saito's (1982) observations for laminar fire whirls and appear to hold true prior to the formation of any vortex breakdown. Zhou et al (2013) also proposed that if one normalizes the fire whirl's flame height with the flame height of a similar nonswirling fire, there is a linear correlation in the logarithmic space between the normalized heights and circulation. Further, based on PIV measurement results, proposed a scaling relationship H = 0.7D 0 * 1.11 , which implies that circulation is the dominant parameter determining a fire whirl's height.…”

Section: Wwwannualreviewsorg • Fire Whirls 205mentioning

confidence: 99%

“…However, the presence of vortex breakdown, which is accompanied by high turbulence and circulation, accounts for the highly effective entrainment in the plume region as well as the growth of b w beyond the intermittent flame zone. High circulation, which may lead to vortex breakdown, increases the inflow rate and subsequently the entrainment through the boundary layer thickness (Zhou et al 2013). Zhou et al's (2013) experimental results suggest that air entrained through the boundary layer is sufficient for sustained complete combustion.…”

Section: Vortex Breakdown Turbulence Suppression and Entrainmentmentioning

confidence: 99%

“…Eventually, the mass flow rate decays in the plume region. Hence, several entrainment zones can be identified along the fire whirl height (Zhou et al 2013). In Lei et al's (2015b) experiments, variations of the mass flow rate with height show that the entrained air through the inflow boundary layer is often not sufficient for stoichiometric combustion of the fuel, even though the air and fuel are relatively well mixed.…”

Section: Vortex Breakdown Turbulence Suppression and Entrainmentmentioning

confidence: 99%

See 4 more Smart Citations

Fire Whirls

Tohidi

Gollner

Xiao

2018

Annu. Rev. Fluid Mech.

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Fire whirls present a powerful intensification of combustion, long studied in the fire research community because of the dangers they present during large urban and wildland fires. However, their destructive power has hidden many features of their formation, growth, and propagation. Therefore, most of what is known about fire whirls comes from scale modeling experiments in the laboratory. Both the methods of formation, which are dominated by wind and geometry, and the inner structure of the whirl, including velocity and temperature fields, have been studied at this scale. Quasi-steady fire whirls directly over a fuel source form the bulk of current experimental knowledge, although many other cases exist in nature. The structure of fire whirls has yet to be reliably measured at large scales; however, scaling laws have been relatively successful in modeling the conditions for formation from small to large scales. This review surveys the state of knowledge concerning the fluid dynamics of fire whirls, including the conditions for their formation, their structure, and the mechanisms that control their unique state. We highlight recent discoveries and survey potential avenues for future research, including using the properties of fire whirls for efficient remediation and energy generation.

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Section: Enclosed Configurationsmentioning

confidence: 99%

Section: Thermal Compositionmentioning

confidence: 99%

Section: Wwwannualreviewsorg • Fire Whirls 205mentioning

confidence: 99%

Section: Vortex Breakdown Turbulence Suppression and Entrainmentmentioning

confidence: 99%

Section: Vortex Breakdown Turbulence Suppression and Entrainmentmentioning

confidence: 99%

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Fire Whirls

Tohidi

Gollner

Xiao

2018

Annu. Rev. Fluid Mech.

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Experimental research on the burning behavior of dragon juniper tree

2017

Self Cite

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Tree crown fire is one of the extreme fire behaviors in the wildland‐urban interface. This paper presents an experimental study on the burning behaviors of single and triple dragon juniper trees. The mass loss, flame height, plume temperature, radiation, and fire interaction are measured. It is found that the foliage moisture content and flame mergence dominate the mass consumed percentage (defined as the ratio of the total mass loss to initially total mass), while the tree crown height and flame mergence determine the flame height. The peak mass loss rate is mainly affected by the moisture content and tree species. For triple tree fires, the peak mass loss rate is also affected by the spacing due to the coupled effects of heat feedback enhancement and air entrainment restriction. Results also show that the flame height significantly increases as the spacing decreases. The spacing holds a significant effect on the fire plume temperature distribution and thermal radiation field. Empirical correlations are also developed for the flame height, radial temperature, and radiant heat flux distribution based on physical interpretation of the tree burning behaviors.

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Experimental studies on characteristics of fire whirl in a vertical shaft

Gao

et al. 2019

Fire and Materials

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Summary An internal fire whirl can be generated readily in a tall shaft model with appropriate gap width at one corner. Experimental study was carried out to investigate the relationship between the characteristics of an IFW and the corner gap width in a 9‐m‐tall vertical shaft model. The vertical shaft had a 2.1 m by 2.1 m square section with gasoline pool fire of different diameters burning inside. The gap width was varied to investigate its impact on fire whirl characteristics, such as flame development, swirling intensity, flame height, flame temperature, and heat release rate of the gasoline pool fire. Vigorous flame swirling motions were generated when the ratio of the gap width to the shaft section perimeter was within the range 0.16 to 0.21. From the flame streamline angle, it was observed that the swirling component was much stronger than buoyancy component near the bottom of burning region. The swirling component decreased and became roughly the same as buoyancy near the middle. Finally, it diminished to being much weaker than buoyancy near the top of the fire. These observations suggest that the Froude number Fr decreased from a large number to 1, and then continued to decrease to 0.

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Effect of flow circulation on combustion dynamics of fire whirl

Cited by 66 publications

References 18 publications

Fire Whirls

Fire Whirls

Experimental research on the burning behavior of dragon juniper tree

Experimental studies on characteristics of fire whirl in a vertical shaft

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