Experimental Study on Flame Height and Radiant Heat of Fire Whirls

Dobashi, Ritsu; Okura, Tetsuya; Nagaoka, Ryosuke; Hayashi, Yujiro; Mogi, Tatsushi

doi:10.1007/s10694-015-0549-z

Cited by 31 publications

(19 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous studies by Morton (1970), Emmons & Ying (1967), and Dobashi et al (2015) suggested that disruption of the cyclostrophic balance at the base and formation of an Ekmantype inflow boundary layer due to viscous effects change the flame shape such that the heat and mass transfer rates on the fuel surface (i.e., the burning rate) increase significantly in relation to nonwhirling fires or whirling flames without viscous effects at their base (Figure 8b). This is consistent with the Ekman-layer solution on a solid surface, where the balance between circulation, pressure gradient, and friction (drag) force within the boundary layer delivers a velocity component toward the low pressure zone, i.e., radial inflow (Kundu et al 2004).…”

Section: Boundary Layer and Burning Ratementioning

confidence: 78%

“…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%

“…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 . Others have modified the setup by installing blowers or air intake at the base to provide sufficient air into the chamber (Byram & Martin 1962, 1970Muraszew et al 1979) or by using variations with six or more walls , Dobashi et al 2015. Figure 4c shows a schematic of the setup with an air intake at the base.…”

Section: Enclosed Configurationsmentioning

confidence: 99%

“…For pool fires and solid combustibles (Martin et al 1976), the velocity of the gasified vapor is minimal, unlike a gas burner, which may impart additional momentum in the axial direction of the fire whirl, similar to a swirling jet. In a liquid pool fire (Byram & Martin 1962, 1970, Snegirev et al 2004, Chuah et al 2009, the swirl establishes an Ekman-like boundary layer over the fuel surface, which draws the flame sheet closer to the fuel surface (Dobashi et al 2015). This provides more heat to the fuel surface and increases the fuel evaporation and burning rate, subsequently entraining more air (this is discussed in more detail in Section 5.3).…”

Section: Enclosed Configurationsmentioning

confidence: 99%

“…(a) Schematic showing the different regions within the boundary layer at the base of a fire whirl (Lei et al 2012). (b) Viscous effects of the Ekman boundary layer on the flame shape at the base of a fire whirl (Dobashi et al 2015).…”

Section: Boundary Layer and Burning Ratementioning

confidence: 99%

See 4 more Smart Citations

Fire Whirls

Tohidi

Gollner

Xiao

2018

Annu. Rev. Fluid Mech.

View full text Add to dashboard Cite

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.

show abstract

Section: Boundary Layer and Burning Ratementioning

confidence: 78%

Section: Enclosed Configurationsmentioning

confidence: 99%

Section: Enclosed Configurationsmentioning

confidence: 99%

Section: Enclosed Configurationsmentioning

confidence: 99%

Section: Boundary Layer and Burning Ratementioning

confidence: 99%

See 3 more Smart Citations

Fire Whirls

Tohidi

Gollner

Xiao

2018

Annu. Rev. Fluid Mech.

View full text Add to dashboard Cite

show abstract

Experimental studies on characteristics of fire whirl in a vertical shaft

Gao

et al. 2019

Fire and Materials

View full text Add to dashboard Cite

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.

show abstract