Generation of an internal fire whirl in an open roof vertical shaft model with a single corner gap

Zou, G. W.; Chow, Wan Ki

doi:10.1177/0734904115569703

Cited by 15 publications

(34 citation statements)

References 22 publications

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“…A fire whirl can be generated by burning a pool fire in a vertical shaft model of appropriate gap widths [11][12][13][14][15]20]. Such experiments were carried out to investigate the effect of the gap width on IFW generation.…”

Section: Experimental Studiesmentioning

confidence: 99%

“…The model was made of wood with a transparent plastics sheet for observing the flame shape and taking pictures. Experiments on varying the width of the vertical gap were carried out with some results reported previously [11,[13][14][15]. 3 A 1.6-kW pool fire of diameter D of 7 cm and containing 25 ml propanol was placed on the ground at the centre of the shaft model.…”

Section: Experimental Studiesmentioning

confidence: 99%

“…An IFW has a fixed physical fire size, and does not spread over the fuel surface as in open space. An IFW can be created in a vertical shaft in tall buildings with appropriate sidewall ventilation arrangement [11][12][13][14][15]. This is hazardous to green buildings with tall shafts or good thermal insulation [16][17][18] and studied as a long-term project.…”

Section: Introductionmentioning

confidence: 99%

“…Swirling flame patterns were observed using a high-speed camera in this long-term research project [11][12][13][14][15] and reported in this paper. Flame heights measured were compared with those observed from a normal camera.…”

Section: Introductionmentioning

confidence: 99%

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Observation on a fire whirl in a vertical shaft using high-speed camera and associated correlation derived

et al. 2021

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The fire whirl generated by burning a pool fire in a vertical shaft with a single corner gap of appropriate width was studied using a high-speed camera. A 7-cm diameter pool propanol fire with heat release rate 1.6 kW in free space was burnt inside a 145-cm tall vertical shaft model with gap widths lying between 2 cm and 16 cm. The flame height was between 0.25 m and 0.85 m for different gap widths. Photographs taken using a high-speed camera at critical times of swirling motion development were used to compare with those taken using a normal camera. From the experimental observations on flame swirling by a high-speed camera, stages for generating the fire whirl were identified much more accurately. Two flame vortex tubes moving over the horizontal burning surface of the liquid pool were observed. Based on these observations a set of more detailed schematic diagrams on the swirling motion was constructed. From the observed flame heights under different gap widths and using three assumptions on the variation of air entrainment velocity with height, an empirical expression relating the burning rate with flame height and the corner gap width was derived from the observation with high-speed camera. The correlation expression of the burning rate of the pool fire obtained would be useful in fire safety design in vertical shafts of tall buildings.

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Section: Experimental Studiesmentioning

confidence: 99%

Section: Experimental Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Observation on a fire whirl in a vertical shaft using high-speed camera and associated correlation derived

et al. 2021

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“…Recently, a series of small to medium-scale vertical shaft fire whirl experiments has been carried out by Chow, Zou and co-workers [5][6][7]. It was demonstrated that the generation of fire whirl could be sub-divided into four stages including (i) initial ignition stage where the flame height is relatively low; (ii) flame rising-up stage where the flame height increase gradually to reach its upcoming state; (iii) stable whirling stage where the flame height is considered to be at its maximum height; (iv) decaying stage where the whirling motion stops and the fire gradually extinguishes.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study on Small-Scale Fire Whirl using Large Eddy Simulation

Yuen¹,

Yeoh²,

Yuen³

et al. 2016

International Conference of Fluid Flow, Heat and Mass Transfer

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-Fire whirl is a rotating fire with either a fixed or revolving flame centre-core caused by unbalanced entrainment. In general, the flame height of a fire whirl is significantly larger than that of a free standing fire. It is suggested by several studies that fire whirl is a disastrous scenario especially in urban or bush fires since it can greatly promote the fire spread and escalate the thread to human lives and species. In this paper, as a preliminary study, the fire whirl behaviour has been studied numerically using the Fire Dynamics Simulator (FDS) ver 6.1.2 which is based on the large eddy simulation (LES). It incorporates the mixture fraction based combustion model along with soot formation, the subgrid-scale (SGS) turbulence model, radiation transfer equation (RTE) model which are fully coupled and interactive. This allows the modelling of all essential chemical and physical behaviours that occur during the fire whirling processes. A small-scale vertical shaft with a base of 0.34 m × 0.35 m with a total vertical height of 1.45 m is considered. The development stages including the ignition, flame-rising and fully-developed fire whirling are modelled successfully through numerical simulations. Fairly good agreements between simulation and experimental results for temperature profiles at the centreline and corner thermocouples are achieved. However, a flame height of 0.3 m to 0.4 m is estimated in the simulation while the experimental observation is around 0.6 m. Also, the temperature is slightly over-predicted at the centre while under-predicted at the corner. These could well be due to the simplified chemistry employed in the FDS. With this preliminary numerical study, it could be logically inferred that the detailed chemical reactions scheme may be needed to capture the fundamental governing characteristics of the fire whirl in future numerical modelling studies.

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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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Generation of an internal fire whirl in an open roof vertical shaft model with a single corner gap

Cited by 15 publications

References 22 publications

Observation on a fire whirl in a vertical shaft using high-speed camera and associated correlation derived

Observation on a fire whirl in a vertical shaft using high-speed camera and associated correlation derived

Numerical Study on Small-Scale Fire Whirl using Large Eddy Simulation

Experimental studies on characteristics of fire whirl in a vertical shaft

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