Experimental and numerical study on the smoke and velocity distribution in an extra-long railway tunnel fire

In this paper, a numerical model verified by a 1:10 small-scale model test was used to study the effect of different smoke vent layouts on fire characteristics and smoke exhaust efficiency. The results show that the total smoke spread length is shortest when four smoke vents are opened near the fire source. If there are more than four smoke vents, some of them will only inhale fresh air rather than smoke. More seriously, some smoke vents will promote the spread of toxic smoke farther. Under different smoke vent layout schemes, the maximum temperature shows the same change trend with the increase in smoke exhaust volume (first increasing and then decreasing). When there are four smoke vents, the temperature field is in a good range compared with other schemes. If four smoke vents are opened, the total smoke exhaust efficiency is highest, and exhaust rate has little influence on total exhaust efficiency. Total smoke exhaust efficiency of the tunnel is more than 93.7% under different exhaust volumes, and the maximum difference of total smoke exhaust efficiency is less than 1.5% under different exhaust volume of Case “4”. The exhaust volume has little influence on temperature decay beneath the ceiling, and a temperature attenuation model of a point exhaust tunnel with four smoke vents was proposed. For the single-side point exhaust tunnels, the number of smoke vents near the exhaust fan side shall not be more than that on the other side. Four smoke vents shall be opened in case of fire and the exhaust volume is 220 m³/s with HRR of 30 MW.

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“…Yao [30] 10 × 5 5-100 0.200 Ji [33] 10 × 5 5-15 0.200 Liang [36] 10 × 7 30 0.20 Ji [37] 10 × 5 3-15 0.167 Guo [38] 10 × 5 3-10 0.167…”

Section: Hrr (Mw) Mesh Sizes (M)mentioning

confidence: 99%

Effect of Different Smoke Vent Layouts on Smoke and Temperature Distribution in Single-Side Multi-Point Exhaust Tunnel Fires: A Case Study

Tao

Zeng

2022

Fire

Self Cite

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“…The fire safety problem in traffic tunnels is the subject of extensive research and analysis presented in many scientific publications. In recent years, the key research directions include the analyses of tunnel ventilation performance in the event of a fire and the analyses of fire smoke spread [1][2][3][4]. Other major directions include technical solutions for reducing smoke density in the tunnel interiors and improving the effectiveness of rescue operations [5][6][7][8], organizational solutions and procedures aimed at reducing risk level [9,10] or analyses the effectiveness of both self-evacuation and rescue operations [1,[11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Influence of Light Wavelengths on Visibility in Smoke during a Tunnel Fire

Koch¹,

Niewiadomski

Wrona

2021

Sustainability

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The occurrence of fire in road tunnels poses high risks to the life and health of people. The resulting smoke, fire gases and high temperatures can be the cause of poisoning and burns. Additionally, dense smoke can significantly reduce visibility, which can result in difficulties during evacuation. This paper aims to investigate the effect of specific wavelengths of visible light on visibility in smoke conditions and to determine the wavelength of light (colour) that can improve visibility in smoke-filled environments. A rubber mixture with polyester and polyamide spacers was selected as a combustible material in order to obtain more realistic conditions with respect to smoke parameters. These plastics are commonly used, among others, in tires, elements of engine plating, upholstery or truck trailer covers. Then, in a test fire chamber laboratory, the colour of light (wavelength) was determined, obtaining the highest transmittance value, understood as the amount of radiation transmitted through the substance. It has been shown that devices emitting a light wave of a specific length can significantly improve visibility in smoke-filled environment.

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