Effects of transverse fire locations on flame length and temperature distribution in a bifurcated tunnel fire

2021 ◽  
Vol 112 ◽  
pp. 103893
Author(s):  
Zhisheng Li ◽  
Yunji Gao ◽  
Xiaosong Li ◽  
Pengfei Mao ◽  
Yuchun Zhang ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Flame Length ◽  
Tunnel Fire

scholarly journals Heat transfer on simplified pre-period stage of tunnel fire

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 799-808
Author(s):  
Hungwei Liu ◽  
Wei Yao
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heating Rate ◽  
Theoretical Solution ◽  
Theoretical Equation ◽  
Thermal Engineering ◽  
Transient Temperature ◽  
Tunnel Fire ◽  
Transient Temperature Distribution ◽  
Heat Transfer Theory

Tunnel fire is a part of applied thermal problems. With increase of transient temperature of the tunnel fire on the structure surface (i.e. tunnel lining), the heat transfer from the surface is possibly varying transient temperature distribution within the structure. The transient temperature distribution is also possibly damaging the composition of structure (micro-crack) because of critical damage temperature. Therefore, the transient temperature distribution has a significantly important role on defining mechanical and physical properties of structure and determining thermal-induced damaged region. The damage at pre-period stage of tunnel fire is perhaps more significant than that at the other period stages because of thermal gradient. Consequently, a theoretical model was developed for simplifying complicated thermal engineering during pre-period stage of tunnel fire. A hollow solid model (HSM) in a combination of dimensional analysis and heat transfer theory with Bessel?s Function and Duhamel?s Theorem were employed to verify a theoretical equation for dimensionless transient temperature distribution (DTTD) under linear transient thermal loading (LTTL). Experimental and numerical methods were also adopted to approve the results from this theoretical equation. The heating rate (M) is a primary variable for discussing DTTD on three means. The heating rate of 10.191, 10 and 240?C/min were applied to experimental and numerical studies. The experimental and numerical results are consistent with the theoretical solution, successfully verifying that the theoretical solution can predict the DTTD well in field. This equation can be used for thermal/tunnel engineers to evaluate the damaged region and to obtain the parameters related to DTTD.

scholarly journals 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 ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1411 ◽  
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.

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

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.

scholarly journals Experimental study on the smoke temperature distribution alongside the lining in tunnel fires

2019 ◽  
Vol 23 (6 Part A) ◽  
pp. 3701-3710 ◽  
Author(s):  
Feng Wang ◽  
Yu Wang ◽  
Yubing Huang ◽  
Qixiang Yan
Keyword(s):  
Temperature Distribution ◽  
Structural Safety ◽  
Small Scale ◽  
Pool Fires ◽  
Test Results ◽  
Vertical Temperature ◽  
Tunnel Fires ◽  
Tunnel Fire ◽  
Key Factor ◽  
Vertical Temperature Distribution

Tunnel fire temperature is a key factor for tunnel structural safety and evacuation. This study aimed to investigate the smoke temperature distribution alongside the lining across the section and effects of pool sizes and fuels on it through a series of small-scale experiments. The results showed the heat release rates of diesel were significantly lower than gasoline?s when they had the same pool size and volume. Nevertheless, the duration of diesel combustion increased obviously. As a result, the maximum smoke temperature under the ceiling for gasoline was significantly higher than diesel?s. The results were subsequently adopted to compare with other test results and illustrated a similar result. The initial temperature rising rates for gasoline pool fires were shown to agree well with the standardized temperature curves, but they were significantly lower for diesel pool fires. Two exponential correlations on vertical temperature distribution were provided, respectively, for gasoline and diesel fires. These findings are expected to be useful for the design of the thermal boundary on the lining in tunnel fires.

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