Study on the smoke back‐layering and critical ventilation in the road tunnel fire at high altitude

Zhang, Shaogang; Wang, Jinhui; He, Kun; Yao, Yongzheng; Peng, Min

doi:10.1002/fam.2714

Cited by 28 publications

(11 citation statements)

References 30 publications

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“…On the other hand, the smoke contains many toxic gases. Therefore, timely and effective control and extraction of the smoke generated from the tunnel fire is of great significance for evacuation and rescue of personnel 1‐7 …”

Section: Introductionmentioning

confidence: 99%

Experimental study on the effect of lateral concentrated smoke extraction on smoke stratification in the longitudinal ventilated tunnel

2020

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Smoke is the main cause of death in tunnel fires. It is one of the important measures to maintain smoke stratification in the early stage of tunnel fire. This article focused on experimentally studying the combined effect of lateral concentrated smoke extraction and longitudinal ventilation on the smoke stratification, which never be revealed before. The velocity of the smoke layer and air layer, vertical temperature distribution, and the flow patterns of the smoke were measured. It was found that the longitudinal ventilation and lateral concentrated smoke extraction would affect the flow of the smoke and change the shear velocity between the smoke layer and air layer, then, the patterns of the smoke layer will be affected. And the flow patterns with Froude (Fr) number can be classified into three categories: (a)Fr < 0.6, with stable smoke stratification; (b) 0.6 < Fr < 0.85, with a stable smoke stratification but the blurring interface; and (c) Fr > 0.85, the smoke layer is completely unstable. The result can provide a reference for ventilation design of immersed tube tunnels.

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Section: Introductionmentioning

confidence: 99%

Experimental study on the effect of lateral concentrated smoke extraction on smoke stratification in the longitudinal ventilated tunnel

2020

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“…35 Ji et al 36,37 explored the effect of ambient pressure on the smoke temperature distribution and smoke movement characteristics and a set of full-scale experiments were conducted by Yan et al 38 to investigate the fire characteristics in a road tunnel at high-altitude areas. Besides, Wu et al 39 and Zhang 40 studied the back-layering length and critical velocity under various ambient pressures. However, Wu et al 39 and Zhang et al 40 only considered small fire scales while both the back-layering length and critical velocity are independent of HRR when HRR is large; and no theoretical analysis were presented.…”

Section: Introductionmentioning

confidence: 99%

“…Besides, Wu et al 39 and Zhang 40 studied the back-layering length and critical velocity under various ambient pressures. However, Wu et al 39 and Zhang et al 40 only considered small fire scales while both the back-layering length and critical velocity are independent of HRR when HRR is large; and no theoretical analysis were presented. So, a comprehensive study on the effect of ambient pressure on the back-layering length and critical velocity is necessary.…”

Section: Introductionmentioning

confidence: 99%

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Effects of ambient pressure on the critical velocity and back-layering length in longitudinal ventilated tunnel fire

Yan

Wang

et al. 2019

Indoor and Built Environment

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Nowadays, the critical velocity and back-layering length are the key parameters in longitudinal ventilation design. However, most studies research them at standard air pressure but ambient pressure decreases at high-altitude area and the reduced ambient pressure could affect the smoke movement characteristics in a tunnel fire. In order to investigate the effect of ambient pressure on the velocity and back-layering length in longitudinal ventilated tunnel, theoretical analysis was carried out first and a series of numerical simulation were conducted with varying heat release rate and ambient pressure. Results show that Li’s model is also reliable under various ambient pressures. The critical velocity under various ambient pressures would become larger with an increase in the heat release rate and would remain stable after the heat release rate reaches a certain value. At smaller heat release rate, the length of counterflow would be higher under reduced ambient pressure while it remains the same when the HRR is large. This could provide reference for tunnel ventilation design at high-altitude areas.

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“…7,8 With the increase of tunnel mileage, the driving density of vehicles will also be increased, so the tunnel safety becomes increasingly serious. Fire is one of the disasters, which may occur in the tunnel, [9][10][11][12][13][14][15][16][17][18][19][20] as the vehicles always carry a lot of solid, liquid, and gaseous combustibles. [21][22][23] When a fire occurs in the tunnel, because of its long-narrow structure, hot smoke will quickly spread throughout the tunnel, and it will be difficult to be discharged in time.…”

Section: Introductionmentioning

confidence: 99%

A numerical study on the effects of naturally ventilated shaft and fire locations in urban tunnels

Fan

Chen

Mao³

et al. 2019

Fire and Materials

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Summary In more and more tunnels, natural ventilation mode with vertical shafts has been gradually employed. However, there are few studies investigating the influences of fire and shaft positions on natural ventilation performance currently. Therefore, this study investigated the effects of the transverse distance from fire source to tunnel sidewall, the longitudinal distance from fire source to shaft, and the transverse distance from shaft to sidewall on natural ventilation effectiveness in a tunnel fire by using Fire Dynamics Simulator. The typical characteristic parameters of smoke, such as mass flow rate, temperature distribution, and velocity vector were analyzed; besides, the phenomenon of plug‐holing was discussed. The results have shown that the mass flow rate of gas exhausted by the shaft decreases slightly with the increase of longitudinal distance from fire source to shaft. When the longitudinal distance from fire source to shaft is constant, changing the transverse distance from shaft to sidewall will have a more obvious effect on the effectiveness of exhausting smoke than changing the transverse distance from fire source to sidewall; in addition, the phenomenon of plug‐holing is more serious when the shaft is close to the sidewall.

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Study on the smoke back‐layering and critical ventilation in the road tunnel fire at high altitude

Cited by 28 publications

References 30 publications

Experimental study on the effect of lateral concentrated smoke extraction on smoke stratification in the longitudinal ventilated tunnel

Experimental study on the effect of lateral concentrated smoke extraction on smoke stratification in the longitudinal ventilated tunnel

Effects of ambient pressure on the critical velocity and back-layering length in longitudinal ventilated tunnel fire

A numerical study on the effects of naturally ventilated shaft and fire locations in urban tunnels

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