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

Fan, Chuangang; Chen, Jian; Mao, Zhanli; Zhou, Yang; Mao, Shaohua

doi:10.1002/fam.2756

Cited by 15 publications

(8 citation statements)

References 59 publications

(97 reference statements)

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“…Huang et al 20 used three cable trays with different cable layouts to conduct fire tests in a closed room and studied the combustion behavior of cable trays on the wall. Fan et al 21 investigated the effects of the transverse distance from fire source to tunnel sidewall, the longitudinal distance from fire source to the shaft, and the transverse distance from the 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.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on fire performance of optical cables used in utility tunnel: Influence of cable spacing and heat flux

Sun

Tang

et al. 2023

Fire and Materials

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Optical cable is an important part of modern telecommunications infrastructure. In this study, cone calorimeter experiments are conducted on the optical cables which are widely being applied in utility tunnels in China. The coupling effect of the spacing between optical cables (8, 10, 12, 15 mm) and the heat flux (30, 40, 50 kW/m2) on fire performance of optical cables is studied. It is highlighted that the optical cables conform to the ignition time model of the thermally thin material. The ignition time of the optical cables decreases when increasing the heat flux. When the heat flux is 30 kW/m2, the ignition time of the optical cable with different spacing varies greatly. When the heat flux is greater than 30 kW/m2, the difference in the ignition time between the optical cable samples with different spacing is small. Furthermore, the average mass loss rate of the optical cables increases when increasing either the heat flux or the spacing between optical cables. The heat release rate of the optical cables also increases when increasing either the heat flux or the spacing between optical cables. The curves of the heat release rate versus time show two peaks, the second one being significantly smaller.

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Section: Introductionmentioning

confidence: 99%

Experimental study on fire performance of optical cables used in utility tunnel: Influence of cable spacing and heat flux

Sun

Tang

et al. 2023

Fire and Materials

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“…The releasing soot from combustion may result in accidental death. [1][2][3] The burning of biomass and fossil fuels emits substantial amounts of particle matter that impacts on public health, reduces air visibility thereby resulting in accidents and economic losses, and even has a significant impact on global climate change. 4,5 The luminous soot can also enhance the radiation from flames.…”

Section: Introductionmentioning

confidence: 99%

“…The soot is generated from combustion process which provides the primary sources of energy. The releasing soot from combustion may result in accidental death 1‐3 . The burning of biomass and fossil fuels emits substantial amounts of particle matter that impacts on public health, reduces air visibility thereby resulting in accidents and economic losses, and even has a significant impact on global climate change 4,5 .…”

Section: Introductionmentioning

confidence: 99%

Number concentration and size distribution of soot aerosols of heptane fire at low pressures

Yang

Wang

et al. 2021

Fire and Materials

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The number concentration and size distribution of soot aerosols are imperative parameters in fire detection which is closely related to safety management, risk assessment, and fire analysis. The experiment of n-heptane pool fire is conducted in a pressure chamber which simulates the 101, 90.9, 80.8, 70.7, 60.6, and 50.5 kPa environments. The influence of air pressure on the number concentration and size distribution of soot aerosols is investigated. The DMS500 fast particulate analyzer is used to analyze the number concentration and size distribution of gas samples. Both the geometric mean diameter and count median diameter of smoke particles increases with pressure. A second-order polynomial equation with correlation coefficient of 0.99 is fitted to the geometric mean diameter of particles against pressure.The particle number concentration is significantly decreased when pressure is reduced according to a linear relationship with correlation coefficient of 0.92. The environmental pressure puts influence on the soot optical properties that affect fire smoke detection technologies used in the regions of different altitudes or air pressures.

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“…In addition, various scholars have studied the impact of height, cross-sectional area, distance from the combustion source, inclination, quantity, and other parameters of the upper vent on the smoke exhaust of the upper vent using a combination of theoretical analysis and numerical simulation. They found that a large cross-sectional area of the upper vent and a longer longitudinal distance from the combustion source contribute more favorably to flue gas emission than the height of the vent, which has a limited contribution [13][14][15]. Moreover, an upper vent that is low in position and slightly inclined can enhance emission efficiency, the best inclination being 76 • [16].…”

Section: Introductionmentioning

confidence: 99%

Environmental Impact of Discharge Patterns and Ambient Wind on the Jet Discharge from a Mechanical Upper Vent of a Tunnel

Xin

Zhu

2021

Applied Sciences

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Flow characteristics and pollutant dispersion characteristics of a mechanical upper vent of a tunnel under various discharge patterns and ambient wind were studied by using the computational fluid dynamics (CFD) numerical method and an experimental model. On this basis, variations in the environmental impact radius rcriti changing with the ambient wind velocity U for pollutants from vertical and horizontal outlets were also analyzed with the set discharge capacity. According to our findings, the pollutant emission of the upper vent under a vertical discharge pattern can be considered as free buoyant jet diffusion under the impact of the momentum of ambient wind, while the emission under the horizontal discharge pattern can be regarded as semi-confined buoyant jet diffusion under the impact of the momentum of ambient wind. Moreover, the rcriti of the vertical outlet increased with the increase of U when U ≤ 3 m/s and was minimally affected by U for U > 3 m/s. Additionally, the rcriti of the horizontal outlet decreased with the increase of U. When the discharge capacity was constant, the rcriti of the upper vent under both vertical and horizontal discharge patterns declined with the increase of the discharge velocity V0. Note that the rcriti of the vertical outlet was smaller than that of the horizontal one for the range of parameters considered. These results can provide a theoretical reference for optimizing the design of a vent on the top of an urban tunnel.

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

Cited by 15 publications

References 59 publications

Experimental study on fire performance of optical cables used in utility tunnel: Influence of cable spacing and heat flux

Experimental study on fire performance of optical cables used in utility tunnel: Influence of cable spacing and heat flux

Number concentration and size distribution of soot aerosols of heptane fire at low pressures

Environmental Impact of Discharge Patterns and Ambient Wind on the Jet Discharge from a Mechanical Upper Vent of a Tunnel

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