Flame extension lengths beneath a confined ceiling induced by fire in a channel with longitudinal air flow

Qiu, Ang; Hu, Longhua; Chen, Longfei; Carvel, Ricky

doi:10.1016/j.firesaf.2018.02.003

Cited by 22 publications

(3 citation statements)

References 23 publications

(33 reference statements)

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“…In tunnel fire scenarios, more attention has been paid to the characteristics of temperature change in the tunnel vault. Qiu et al [8] conducted full-scale tunnel fire tests and found that the temperature of the tunnel vault exhibited an exponential decay along the longitudinal direction. Lee et al [9] found that the temperature at the top of the tunnel near the fire source decreases with an increase in aspect ratio, and the reduction rate decreases with a decrease in heat loss.…”

Section: Introductionmentioning

confidence: 99%

Study on the Effect of Natural Wind on the Smoke Spread Law of Extra-Long Tunnel Fires with Inclined Shafts for Air Supply and Exhaust

Tan,

Wang,

Zhang

et al. 2024

Buildings

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High-temperature smoke generated by tunnel fires is the most important factor causing casualties. To explore the influence of natural wind on fire smoke movement in an extra-long highway tunnel based on the Taihang Mountain Tunnel, the distribution law of natural wind in the tunnel was obtained by on-site monitoring of the meteorological conditions at the tunnel site. A three-dimensional fire dynamics tunnel model considering an inclined shaft smoke exhaust was established, and the influence of natural wind on tunnel temperature distribution, smoke spread and smoke exhaust efficiency was studied. The results show that the natural wind speed of the Taihang Mountain Tunnel is mainly concentrated at 0~3 m/s. The main wind direction of the natural wind on the left tunnel is opposite to the driving direction, and the distribution probability of the main wind direction in each section is 81.27% and 72.15%, respectively. The main wind direction of the right tunnel is the same as the driving direction, and the distribution probability of the main wind direction in each section is 56.78%, 69.73%, 67.32% and 64.65%, respectively. The negative natural wind can inhibit the smoke spread downstream of the smoke exhaust port, but it is not conducive to the smoke exhaust. The positive natural wind promotes the smoke spread to the downstream of the smoke exhaust port, and the larger the natural wind speed, the longer the spread length. Natural wind reduces the smoke exhaust efficiency. For positive or negative natural wind with a guaranteed rate of 70%, the smoke exhaust efficiency is reduced by 27.76% and 15.59%, respectively, compared with the condition without natural wind. The research results can provide a useful reference for the design of fire smoke exhausts and smoke control schemes in extra-long highway tunnels.

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Section: Introductionmentioning

confidence: 99%

Study on the Effect of Natural Wind on the Smoke Spread Law of Extra-Long Tunnel Fires with Inclined Shafts for Air Supply and Exhaust

Tan,

Wang,

Zhang

et al. 2024

Buildings

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“…On the other hand an experimental study on temperature evolution inside the compartment with fire growth and flame ejection through an opening under external wind was considered by Hu, Longhua, et al [8]. They also considered the characterization of buoyant flow stratification and flame extension lengths in the tunnel fires [9,10]. Wan, Huaxian, et al [11] investigated a numerical study on the smoke back-layering length and inlet air velocity of fires in an inclined tunnel under natural ventilation with a vertical shaft.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of the Effects of the Jet Fan Speed, Heat Release Rate and Aspect Ratio on Smoke Movement in Tunnel Fires

et al. 2020

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In this study, the effects of the jet fan speed, heat release rate and aspect ratio on smoke movement in tunnel fires have been investigated. The jet fan speed was changed from 6.25 (25%) to 12.5 m/s (50%), 18.75 m/s (75%), and 25 m/s (100%). The heat release rate was set up from 3.9 to 6 MW and 16 MW, the aspect ratio was changed from 0.6 to 1 and 1.5, respectively. The lower the jet fan speed is, the longer the smoke back-layering length is. With a higher velocity, the smoke tends to move out of the tunnel quickly; however, smoke stratification also occurs, and this reduces visibility. This could make it difficult for people to evacuate. With a higher heat release rate, the smoke tends to move far away from the fires quickly when compared with other cases. Additionally, the higher the heat release is, the longer the smoke back-layering is. Finally, with a higher aspect ratio, the smoke back layering length in the tunnel is also longer. The smoke layer thickness is also larger than in other cases. The correlation of velocity, heat release rate and aspect ratio has been investigated to avoid the smoke back layer length in tunnel fires.

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“…Therefore, it is most important that the ventilation system is able to force the smoke movement in desired direction and with precisely determined velocity, called critical velocity [2]. Accurate determination of the value of critical velocity is a very important issue: it cannot be too low because it would not be able to force the desired flow direction, it cannot be too high as well because it would induce the fire growth, especially for HGV fires [4,5]. It could also disturb the stratification of the layers of clear air and smoke [6,7].…”

Section: Introductionmentioning

confidence: 99%

Transient Analyses and Energy Balance of Air Flow in Road Tunnels

Król

2018

Energies

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The issue of airflow dynamic in a road tunnel is considered in this study and its impact on smoke management and people safety is highlighted. It was an attempt to estimate the time needed to reach a final steady state of airflow when the operation mode of jet fans was switched. The numerical model of the tunnel was solved with the use of Ansys Fluent. To reproduce the decrease of atmospheric pressure with height, relative static pressure was applied using UDF (User Defined Function). The ambient weather conditions were taken into account as well. The wind influence was introduced by the additional component of dynamic pressure applied against one of the tunnel portals also using UDF. There are some theoretical foundations of airflow in a tunnel presented in this paper. The obtained results were compared with the measurements carried out in a real road tunnel and the results obtained while applying the above-mentioned physical model. The main contribution of the presented work is the indication of a relatively high relaxation time of airflow in a tunnel, which could be important when designing the emergency pattern of a ventilation system. Additionally, some considerations of kinetic energy exchange between fan jet and air volume would be helpful when choosing fans for ventilation systems being designed.

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Flame extension lengths beneath a confined ceiling induced by fire in a channel with longitudinal air flow

Cited by 22 publications

References 23 publications

Study on the Effect of Natural Wind on the Smoke Spread Law of Extra-Long Tunnel Fires with Inclined Shafts for Air Supply and Exhaust

Study on the Effect of Natural Wind on the Smoke Spread Law of Extra-Long Tunnel Fires with Inclined Shafts for Air Supply and Exhaust

Numerical Study of the Effects of the Jet Fan Speed, Heat Release Rate and Aspect Ratio on Smoke Movement in Tunnel Fires

Transient Analyses and Energy Balance of Air Flow in Road Tunnels

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