A physical model-free ant colony optimization network algorithm and full scale experimental investigation on ceiling temperature distribution in the utility tunnel fire

Fire-induced thermal flow is the greatest threat to trapped people and the heat-resistant quality of building structures. This paper presents an experimental investigation of the effects of external wind on the ceiling temperature distribution of fire-induced thermal flow in a one-sixth scale corridor connected to a compartment. In the experiments, the fire source was placed in the compartment with hot thermal flow spilled into the connected corridor. The heat release rate (HRR) was changed from 10 to 20 kW and the external wind velocity was changed from 0 to 2.09 m/s. The ends of the corridor could be adjusted to be fully or partially open to the environment with dam-boards arranged at the ends of the corridor. An effective corridor HRR, Qcorridor, was defined to account for the amount of the spilled plume into the corridor. Results show that the temperature under the ceiling changed in a non-monotonic way with wind velocity: it first increased and then decreased with wind velocity. It was revealed that the dam-boards at the corridor opening had an evidently shielding effect, leading to higher temperature compared to the fully open environment. Finally, uniform correlations are proposed for predicting the attenuation law of ceiling temperature profiles in corridors for different wind conditions.

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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 on Underground Utility Tunnel Fire Characteristics under Sealing and Ventilation Conditions

Advances in Civil Engineering ◽

10.1155/2020/9128704 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Hongtao Zhang ◽

Yufei Zhao

Keyword(s):

Safety Evaluation ◽

Maximum Temperature ◽

Physical Parameters ◽

Road Tunnel ◽

Tunnel Fire ◽

Ceiling Temperature ◽

Ventilation Modes ◽

Utility Tunnel ◽

Fire Characteristics ◽

Ventilation Conditions

With the development of the underground utility tunnel in China, the safety evaluation during facility operation inside tunnels is increasingly important after construction. In contrast to fixed fire source in the traffic tunnel, the fire characteristics of the electric cable compartment of the utility tunnel with different ventilation modes are studied. Firstly, the thermal physical parameters of cable material are determined by experiment and numerical simulation. Different fire sealing and ventilation conditions are established according to the practical utility tunnel engineering in FDS. The maximum temperature and smoke gas concentrations are obtained, as well as the heat release rate. The results show that the utility tunnel fire has obvious differences compared with road tunnel fire, where the maximum ceiling temperature and the distributions of smoke is related to fire sealing and ventilation mode. Some suggestions related to evaluation and firefighting are provided for practical purposes.

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Numerical study on the effect of shaft position on natural smoke exhaust in tunnels with one closed portal

E3S Web of Conferences ◽

10.1051/e3sconf/202019405061 ◽

2020 ◽

Vol 194 ◽

pp. 05061

Author(s):

GENG Pengqiang ◽

WANG Zihao ◽

WENG Miaocheng ◽

LIU Fang

Keyword(s):

Temperature Distribution ◽

Heat Release ◽

Release Rate ◽

Numerical Study ◽

Fire Dynamics ◽

Fire Dynamics Simulator ◽

Fire Source ◽

Tunnel Fire ◽

Ceiling Temperature ◽

Longitudinal Distance

.This paper uses Fire Dynamics Simulator (FDS) to study the effect of the longitudinal distance from the shaft to the fire source on the natural smoke exhaust of the tunnel fire with one closed portal, and analyzes the temperature distribution of the smoke and the shaft’s smoke exhaust efficiency. The results show that when the shaft is located downstream of the fire source (Ds<0), with the increase of the distance from the shaft to the fire source, the smoke exhaust efficiency decreases first and then stabilizes at a fixed value. At this time, the ceiling temperature attenuation’s coefficient at upstream of the fire source is only related to the heat release rate of the fire source (HRR). When the shaft is located upstream of the fire source (Ds>0), the smoke exhaust efficiency increases slightly with the increase of the distance from the shaft to the fire source, but the overall value is relatively small. When HRR is fixed, the shaft located downstream of the fire source has a higher smoke exhaust efficiency. As the distance between the shaft and the fire source increases, the plug phenomenon decreases.

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