Experimental research on combustion dynamics of medium-scale fire whirl

Lei, Jiao; Liu, Naian; Zhang, Li Min; Chen, Haixiang; Shu, Li; Chen, Pu; Deng, Zhihua; Zhu, Jianqin; Satoh, Kohyu; Ris, John L. de

doi:10.1016/j.proci.2010.06.009

Cited by 95 publications

(53 citation statements)

References 15 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%

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%

Fire Whirls

Tohidi

Gollner

Xiao

2018

Annu. Rev. Fluid Mech.

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“…In the stage of quasi-steady burning, both buoyancy and drag force control the burning, inducing higher instability with strong convection. In this sense, it can be implied that the flow instabilities, as evidenced by the flame wander, may be caused by the drag force which suppresses turbulent fluctuations [8]. Figure 4 shows the data of 2 s averaged pressure difference and temperature versus time, for fire whirl with pool diameter of 50 cm.…”

Section: Burning Rate Of Fire Whirl: Drag Force Effectmentioning

confidence: 99%

“…The fire whirl flame could be well regarded as a cylindrical and blackbody homogeneous emitter, according to its shape and the analysis above. The diameter and height of the cylinder are respectively the pool diameter D and flame height H which can be determined from flame video or from the flame height correlation [8]. Thus, the emitted energy from the fire whirl can be expressed as Q is the total heat release rate; E f is the emissive power of the flame at the surface.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…Morton [5] especially examined the origin, generation and amplification of concentrated vorticity of fire whirl by analysis of relevant vorticity equations. The burning behaviors including burning rate, flame height and flame temperature were mainly investigated by experimental researchers, such as Emmons and Ying [7] by rotating screen-flame model, Soma and Saito [2] and Kuwana et al [3] utilizing bench-scale model by scaling laws, and Lei et al [8] by fixed frame-flame model. In recent years, numerical simulations [9,10] have also been widely used for solving the Navier-Stokes or vorticity equations of fire whirl, in order to interpret the detailed fluid flow structure.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Research on Burning Rate, Vertical Velocity and Radiation of Medium-Scale Fire Whirls

Zhou¹,

Liu²,

Satoh³

2011

Fire Safety Science - Proceedings of the 10th International Sym

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Fire whirls are often reported in forest and urban fires with devastating damage to life and property. This work conducted experiments using a medium-scale facility to study the initiation mechanism, the vertical velocity and radiative heat transfer of fire whirls. Heptane was used as the fuel in the experiments. The variations of burning rates versus time indicate that the drag force on the root of the flame plays an important role in the initiation and decay of a fire whirl. Analyses show that the pressure difference due to whirling, characterized by the circulation  , significantly affects the vertical centerline velocity. The variation of the vertical centerline velocity is correlated by , where m is nearly 1.1 for both fire whirls and general pool fires. It is also found that the radiative fraction of fire whirls is nearly 42 %, 1.4 times as large as that for general pool fires. The radiative heat feedback fraction is shown to increase with pool diameter, similarly as for general pool fires. KEYWORDS: fire whirl, radiation, centerline velocity, burning rate, pool fires. NOMENCLATURE LISTING

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“…회오리 화염은 보기 드문 현상이지만 일반적인 화 재에 비해 매우 파괴적이며, 화염길이의 증가로 인해 불티 등의 불씨가 멀리까지 전파되어 화재를 확대시키고, 연소 속도가 증가하면서 높은 연소열로 인한 원활한 소화활동 의 어려움 등으로 인해 인명 및 재산상의 큰 피해를 초래 할 수 있다 (4,5) . 풀 화재에 대한 연구사례를 살펴보면, 메탄올 풀 화재에 대한 난류화염의 연구 (6) , 비정상 상태의 풀 화재에서 액체 의 온도에 의한 연소속도 (7) , 풀 화재시 열전달에 의하여 고 온 영역이 형성되는 현상과 열전달 기구 등에 대해 연구 (8) , 풀 화재의 연소 특성 (9,10) , 화점높이 변화에 따른 pool fire 의 연소특성 (11) (12) 하였으며, 약한 회오리 화염의 화염 길이에 대한 연소속도의 영향과 축대칭 실험실 규모 회오 리 화염의 화염 높이에 관한 이론적 및 실험적 연구 (13,14) , 직경 5 cm의 메탄올 풀 화재에서 발생되는 회오리 화염의 모델링과 소규모 회오리 화염의 화염높이와 화염 형상 예 측 (15,16) , 고정 프레임 형태의 회오리 화염에 대한 실험적 연구 (17) , 회오리 화염의 연소특성에 관한 연구와 회오리 화 염의 연소특성과 FDS를 이용한 회오리 화염 해석에 관한 연구 (18,19) , 화점높이 변화에 따른 whirl fire의 질량감소 및 공기유입속도에 관한 연구 (20) (20) . , 회오리 화염의 경우 27.69 g/secm 2 로 최대값을 나타낸 후 화점높이가 증가할수 록 감소하는 경향을 나타내었다.…”

Section: 서 론unclassified

Combustion Characteristics of Pool and Whirl Fire on Methanol by Height of Fire Source using the Small Scale

Park

2012

Journal of Korean Institute of Fire Science and Engineering

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This study is intended to understand flame behavior of pool and whirl fire by height of fire source. Liquid fuel was methanol which is used in many studies for pool and whirl fire. Size of vessel was 100 × 100 × 50 and the vessel was made by stainless steel. Combustion time, mass loss rate, flame temperature, flame height and air entrainment rate from the outside to flame were measured, and flame behavior was visualized with video camera. Based on the experiment, it was found that combustion characteristics by height of fire source got a more effect on whirl fire than pool fire.

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Experimental research on combustion dynamics of medium-scale fire whirl

Cited by 95 publications

References 15 publications

Fire Whirls

Fire Whirls

Experimental Research on Burning Rate, Vertical Velocity and Radiation of Medium-Scale Fire Whirls

Combustion Characteristics of Pool and Whirl Fire on Methanol by Height of Fire Source using the Small Scale

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