A Evaluation Study of Local Smoke Control Facility for the Smoke Spread Prevention on Tunnel Fire

Metro trains running in tunnels cause piston wind, and when a metro train stops in a tunnel due to a fire, the effect of the piston wind on smoke propagation characteristics cannot be ignored. In this paper, a theoretical model based on the unsteady flow theory of the Bernoulli equation was established to describe the change in piston wind speed under fire conditions. The characteristics of the smoke propagation in tunnel fires under the effect of the piston wind were analysed by means of numerical simulation. The result indicates that the piston wind has a significant effect on the characteristics of smoke distribution. In a longitudinally ventilated tunnel, whether the direction of piston wind is the same as that of longitudinal ventilation could seriously affect the control of fire smoke. When the direction is the same, the piston wind could enhance the smoke control effect of the longitudinal ventilation. Otherwise, the smoke control effect could be significantly diminished, and the smoke control by the critical wind speed of longitudinal ventilation would fail. The findings could contribute to a better understanding of the characteristics of tunnel fire to control smoke spread under the influence of piston wind.

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Influence of tunnel curvature on smoke spread in a tunnel fire

Journal of the Chinese Institute of Engineers ◽

10.1080/02533839.2020.1719897 ◽

2020 ◽

Vol 43 (4) ◽

pp. 386-396 ◽

Cited By ~ 1

Author(s):

Bo Lou ◽

Qin Rifu ◽

Eric Hu ◽

Qin Jiyun ◽

Huang Zhenwen

Keyword(s):

Tunnel Fire ◽

Smoke Spread

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Note on the impact of slope on smoke spread in tunnel fire conditions

Journal of Physics Conference Series ◽

10.1088/1742-6596/1141/1/012150 ◽

2018 ◽

Vol 1141 ◽

pp. 012150

Author(s):

J Glasa ◽

L Valasek ◽

P Weisenpacher

Keyword(s):

Tunnel Fire ◽

Smoke Spread ◽

The Impact ◽

Fire Conditions

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On the Use of Solid Curtains Near Smoke Extraction Vents to Control Smoke Spread Resulting From Fire in Road Tunnels

Journal of Thermal Science and Engineering Applications ◽

10.1115/1.4048670 ◽

2020 ◽

Vol 13 (3) ◽

Author(s):

Taher Halawa

Keyword(s):

High Temperature ◽

Release Rate ◽

Control Strategy ◽

Smoke Control ◽

Smoke Spread ◽

Peak Heat Release Rate ◽

Road Tunnels ◽

Low Visibility ◽

Temperature Levels ◽

Fire Accidents

Abstract The effectiveness of the smoke control strategy plays an important role in increasing safety levels when fire accidents occur in road tunnels. This paper introduces clarifications about how the efficiency of smoke extraction control using solid curtains can be increased by placing smoke extraction vents close to the solid curtains. The effect of adding a solid curtain with different heights and at various positions relative to a smoke extraction vent was studied in this paper. A 14.3% increase in the vent flowrate occurs at the time corresponding to the fire peak heat release rate when the distance between the solid curtain and the vent is equivalent to 90% of the tunnel height and when the solid curtain height is equal to 16% of the tunnel height. High temperature and low visibility conditions occur near the solid curtain at the smoke-trapped area when the smoke curtain height exceeds 40% of the tunnel height. Using a solid curtain positioned far away from the vent with a distance equals to 90% of the tunnel height and with a height in the range from 16% to 30% of the tunnel height achieves the best results in terms of suppression of smoke spread and attaining acceptable visibility and temperature levels at the region where the smoke is trapped by the solid curtain.

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A Study on Ceiling Temperature Distribution and Critical Exhaust Volumetric Flow Rate in a Long-Distance Subway Tunnel Fire with a Two-Point Extraction Ventilation System

Energies ◽

10.3390/en12081411 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1411 ◽

Cited By ~ 7

Author(s):

Peng Zhao ◽

Zhongyuan Yuan ◽

Yanping Yuan ◽

Nanyang Yu ◽

Tao Yu

Keyword(s):

Temperature Distribution ◽

Flow Rate ◽

Empirical Equation ◽

Ventilation System ◽

Volumetric Flow Rate ◽

Subway Tunnel ◽

Smoke Control ◽

Long Distance ◽

Tunnel Fire ◽

Ceiling Temperature

Smoke control is a crucial issue in a long-distance subway tunnel fire, and a two-point extraction ventilation system is an effective way to solve this problem, due to the characteristics of controlling the smoke in a limited area and removing high-temperature and toxic smoke in time. In this study, the ceiling temperature distribution and the critical exhaust volumetric flow rate to control the smoke in the zone between two extraction vents were investigated in a long-distance subway tunnel fire with a two-point extraction ventilation system. Experiments were carried out in a 1/20 reduced-scale tunnel model based on Froude modeling. Factors, including the heat release rate (HRR), the extraction vent length, the internal distance between two extraction vents and exhaust volumetric flow rate, were studied. Smoke temperature below the ceiling, exhaust volumetric flow rate and smoke spreading configurations were measured. The ceiling temperature distribution was analyzed. Meanwhile, an empirical equation was developed to predict the critical exhaust volumetric flow rate based on the one-dimensional theory, experimental phenomenon and the analysis of forces acting at the smoke underneath the extraction vent. The coefficients in the empirical equation were determined by experimental data. Compared with the experimental results, the developed empirical equation can predict the critical exhaust volumetric flow rate well. Research outcomes in this study will be beneficial to the design and application of two-point extraction ventilation system for a long-distance subway tunnel fire.

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Study of Fire Smoke Flow of Tunnel at Different Longitudinal Ventilation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.226-228.1472 ◽

2012 ◽

Vol 226-228 ◽

pp. 1472-1475

Author(s):

Pei Pei Yang ◽

Xiao Lu Shi ◽

Bi Ming Shi

Keyword(s):

Flow Resistance ◽

Reverse Flow ◽

Ventilation System ◽

Gas Temperature ◽

Smoke Control ◽

Smoke Flow ◽

Longitudinal Ventilation ◽

Smoke Spread ◽

Fire Smoke ◽

Safety Evacuation

Once the tunnel fires happened, it will cause a major accident. And the smoke control of the runnel is important to fire prevention. A numerical simulation of the fire smoke flow in the tunnel model is presented by using FDS. The influence of different longitudinal ventilation on fire smoke flow of tunnel is obtained. And providing theory basis for tunnel ventilation system design, smoke spread control and safety evacuation. The results shown that in order to avoid reverse-flow and extend the time of smoke at the top of tunnel, the longitudinal speed should be controlled in 3.4 m/s; because of the role of longitudinal ventilation, smoke flow resistance and longitudinal ventilation generated by the effect of smoke flow resistance make the gas temperature first rise and then down.

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The Study of the Confinement Velocity in the Longitudinal Ventilation Tunnel Fire

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.446-449.3665 ◽

2012 ◽

Vol 446-449 ◽

pp. 3665-3669

Author(s):

Ke Qing Sun ◽

Hui Yang

Keyword(s):

Characteristic Parameter ◽

Experimental Models ◽

Experimental Results ◽

Mixed Gas ◽

Control Effect ◽

Smoke Control ◽

Tunnel Fire ◽

Longitudinal Ventilation ◽

The Relationship ◽

Two Sides

For the situation that the smoke exhaust vents are located on both sides of the fire source, critical ventilation velocity is not appropriate to evaluate the smoke control effect. “Confinement velocity” is proposed as the characteristic parameter to study the longitudinal ventilation by O.Vauquelin in this situation. However, there have been few studies on confinement velocity. An experimental study was carried out on two reduced scale tunnel models. The main objective is to analysis the relationship between confinement velocity and fire heat release in this situation. Helium and air in different ratio was used as the smoke, and the "cold smoke" produced by smoke generator was put into the mixed gas in order to measure the length of smoke layer. The experimental models were based on the half tunnel as flow field at two sides of fire is symmetrical. The CFD model was created on the basis of the experiment, and the results were basically accord with the experimental results. It was shown from the experimental results that the critical point of the confinement velocity is between L / H = 2 to L / H = 4 in section 1, between L / H = 1 to L / H = 2 in section 2, rather than a fixed value; Two tunnel models had similar dimensionless confinement velocity, but the dimensionless total confinement velocity was different.

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Numerical Study of Smoke Control for Underground Platform in a High-Speed Railway Station

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.256-259.2803 ◽

2012 ◽

Vol 256-259 ◽

pp. 2803-2812 ◽

Cited By ~ 2

Author(s):

Hua Yang ◽

Richard Yuen ◽

He Ping Zhang

Keyword(s):

Urban Space ◽

High Speed ◽

Numerical Study ◽

Exhaust System ◽

Cfd Modeling ◽

Smoke Control ◽

Railway Station ◽

High Speed Railway ◽

Fire Engineering ◽

Smoke Spread

Smoke control for the underground platform of a high-speed railway station was investigated. Nowadays, the development of high-speed railway in China is rapid. In order to economize valuable urban space and to realize the convenient interchange to the subway, some of the high-speed railway station platforms and transfer halls are set underground. It is difficult and uneconomic to achieve static ventilation in the underground platform. Therefore, The mechanical smoke control system is the most feasible and most reliable method to ensure the fire safety of the underground platform. How to protect the evacuation stairs free from the threat of fire-induced smoke is a major concern of smoke control in the underground platform. An underground island platform and underground waiting and transfer halls of an under construct high-speed railway station in south China are reconstructed in this paper. Three smoke control modes based on mechanical ventilation, namely mechanical air makeup, pressurized air supply for stairwell and air curtain, are numerically simulated by Computational Fluid Dynamics (CFD) method. The distribution of smoke, temperature, and CO in the platform and influences of them on evacuation staircases are computed and analyzed. The effect of fire location in smoke spread are explored in our research. This study based on CFD modeling enables the improvement of the design and operation of smoke control and exhaust system for underground high-speed railway station. The results are applicable to practical fire engineering designs for underground high-speed railway station platform.

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