scholarly journals Experimental Investigation on the Discharge of Pollutants from Tunnel Fires

2020 ◽  
Vol 12 (5) ◽  
pp. 1817
Author(s):  
Lihua Zhai ◽  
Zhongxing Nong ◽  
Guanhong He ◽  
Baochao Xie ◽  
Zhisheng Xu ◽  
...  
Keyword(s):  
Laser Sheet ◽  
Longitudinal Velocity ◽  
Release Rates ◽  
Layer Height ◽  
Tunnel Fires ◽  
Smoke Flow ◽  
Longitudinal Ventilation ◽  
Toxic Gases ◽  
Smoke Layer ◽  
Series Of Experiments

Many pollutants are generated during tunnel fires, such as smoke and toxic gases. How to control the smoke generated by tunnel fires was focused on in this paper. A series of experiments were carried out in a 1:10 model tunnel with dimensions of 6.0 m × 1.0 m × 0.7 m. The purpose was to investigate the smoke layer thickness and the heat exhaust coefficient of the tunnel mechanical smoke exhaust mode under longitudinal wind. Ethanol was employed as fuel, and the heat release rates were set to be 10.6 kW, 18.6 kW, and 31.9 kW. The exhaust velocity was 0.32–3.16 m/s, and the longitudinal velocity was 0–0.47 m/s. The temperature profile in the tunnel was measured, and the buoyant flow stratification regime was visualized by a laser sheet. The results showed that the longitudinal ventilation leads to a secondary stratification of the smoke flow. In the ceiling extract tunnel under longitudinal ventilation, considering the research results of the smoke layer height and the heat exhaust coefficient, a better scheme for fire-producing pollutants was that an exhaust velocity of 1.26–2.21 m/s (corresponding to the actual velocity of 4.0–7.0 m/s) should be used. The longitudinal velocity should be 0.16–0.32 m/s (corresponding to the actual velocity of 0.5–1.0 m/s).

Study on the heat exhaust coefficient and smoke flow characteristics under lateral smoke exhaust in tunnel fires

2019 ◽  
Vol 43 (7) ◽  
pp. 857-867 ◽  
Author(s):  
Zhisheng Xu ◽  
Qiulin Liu ◽  
Lu He ◽  
Haowen Tao ◽  
Jiaming Zhao ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Tunnel Fires ◽  
Smoke Flow

Determinations of the fire smoke layer height in a naturally ventilated room

2013 ◽  
Vol 58 ◽  
pp. 1-14 ◽  
Author(s):  
Chi-ming Lai ◽  
Chien-Jung Chen ◽  
Ming-Ju Tsai ◽  
Meng-Han Tsai ◽  
Ta-Hui Lin
Keyword(s):  
Layer Height ◽  
Fire Smoke ◽  
Smoke Layer

Study of Fire Smoke Flow of Tunnel at Different Longitudinal Ventilation

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.

Smoke Control in Subway Tunnel Fires

2014 ◽  
Vol 638-640 ◽  
pp. 2027-2030
Author(s):  
Xiao Xiong Zha ◽  
Sheng Zeng ◽  
Yi Yan Chen ◽  
Rui Juan Jiang
Keyword(s):  
Computer Simulation ◽  
Theoretical Analysis ◽  
Critical Velocity ◽  
Simple Formula ◽  
Control Mode ◽  
Subway Tunnel ◽  
Smoke Control ◽  
Release Rates ◽  
Tunnel Fires ◽  
Ventilation Velocity

This paper concerns the smoke control modes and the critical ventilation velocity when the subway tunnel on fires. The standard for the smoke control mode is making sure the smoke exhausting in the shortest way. The critical ventilation velocity means it is just sufficient to prevent the smoke spreading upstream. The critical velocity in different heat release rates obtained though theoretical analysis and computer simulation. In the end, a simple formula to calculate the critical velocity can be fitting out.

The maximum temperature of buoyancy-driven smoke flow beneath the ceiling in tunnel fires

2011 ◽  
Vol 46 (4) ◽  
pp. 204-210 ◽  
Author(s):  
Ying Zhen Li ◽  
Bo Lei ◽  
Haukur Ingason
Keyword(s):  
Maximum Temperature ◽  
Tunnel Fires ◽  
Smoke Flow

scholarly journals Temperature stratification in a road tunnel

2016 ◽  
Vol 20 (1) ◽  
pp. 223-237 ◽  
Author(s):  
Brahim Kalech ◽  
Zouhaier Mehrez ◽  
Mourad Bouterra ◽  
Cafsi el ◽  
Ali Belghith
Keyword(s):  
Richardson Number ◽  
Numerical Study ◽  
Barrier Effect ◽  
Ventilation Strategy ◽  
Road Tunnel ◽  
One Dimensional ◽  
Smoke Flow ◽  
Smoke Layer ◽  
And Training ◽  
Good Agreement

Tests were conducted to study the temperature distribution and stratification of smoke in a tunnel at one-dimensional propagation phase, the ventilation strategy varies in these trials. Numerical results showed that there are three layers of flow in the different strategies, the smoke layer, intermediate mixture layer and training fresh air layer. A barrier effect has been shown for the distribution of the temperature of the smoke upstream. The temperature and the velocity of movement of the smoke flow were influenced by the type of ventilation strategy. Stratification of the flow is characterized by a Richardson number. This numerical study requires validation with the work of Hu et al. [11]. However, a good agreement was obtained.

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