Study of smoke back-layering length with different longitudinal fire locations in inclined tunnels under natural ventilation

Kong, Jie; Xu, Zhisheng; You, Wenjiao; Wang, Beilei; Yin, Liang; Chen, Tao

doi:10.1016/j.tust.2020.103663

Cited by 52 publications

(23 citation statements)

References 39 publications

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“…The 2 m × 2 m × 5 m shaft is located 30 m to the right of the fire source. The tunnel walls (side walls, ceilings, and floors) are set as an inert smooth surface without considering the friction coefficient, which is also the common setting in previous studies in the literature on tunnel fires (eg, References 29‐32). Besides, the boundaries of both portals of the tunnel are assigned as “OPEN” to the external ambient environment.…”

Section: Numerical Simulationmentioning

confidence: 99%

“…The model setup is shown in The mixing-controlled combustion model is the default setting used for FDS LES (large eddy simulation), which assumes that a single hydrocarbon fuel is being burned with a constant fraction of fuel converting into CO and soot. It has been widely applied in the studies concerning tunnel fires [29][30][31][32] and is adopted in this work.…”

Section: Model Designmentioning

confidence: 99%

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Influences of inclined tunnel ceiling on plug‐holing phenomenon and mechanical smoke exhaust efficiency in tunnel fires

Zhao

Wang

et al. 2021

Fire and Materials

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Summary In this paper, the effect of inclined tunnel ceiling on the characteristic of smoke extraction and the efficiency of mechanical smoke exhaust is studied. The parameters of different ceiling inclination angles, exhaust velocities, and heat release rates in the tunnel fire are taken into account. The results demonstrate that for the given smoke exhaust velocity and heat release rate, as the ceiling inclination angle increases, the smoke flow tends to accumulate toward the centerline of the tunnel ceiling, which increases the temperature of the smoke layer and relieves the phenomenon of plug‐holing beneath the shaft. The applicability of previous Fr criterion for predicting whether the plug‐holing phenomenon occurs is also verified. It is shown that the Fr criterion of Fr = 1.5 can also be applicable to the tunnel with different inclination angles. In addition, a predicted correlation for the mechanical smoke exhaust efficiency is established by taking the effect of inclined tunnel ceiling into account, and the predicted value is in good agreement with the results in this paper. This work provides an improved understanding of mechanical smoke extraction in tunnel with inclined ceiling. It may also serve as a reference for the design of a mechanical smoke exhaust system.

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Section: Numerical Simulationmentioning

confidence: 99%

Section: Model Designmentioning

confidence: 99%

Influences of inclined tunnel ceiling on plug‐holing phenomenon and mechanical smoke exhaust efficiency in tunnel fires

Zhao

Wang

et al. 2021

Fire and Materials

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“…FDS uses LES turbulence model by default, thus a list of researchers, who use LES is long [31][32][33]. It is dedicated for low-Mach buoyancy driven flows, which are specific for the fire phenomenon.…”

Section: Selecting Of the Turbulence Modelmentioning

confidence: 99%

Some Tips on Numerical Modeling of Airflow and Fires in Road Tunnels

Król

2021

Energies

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The efficiency of tunnels systems is often evaluated using numerical simulations. This concerns both to normal and emergency mode of tunnel systems operation. Therefore the safety level of tunnel users may depend on the quality of numerical models being built. The most often studied areas cover the researches on natural and forced airflows in the normal mode and on fire development and smoke spreading in the emergency mode as well as modeling of fan operation. Thus, many software packages implementing Computational Fluid Dynamics (CFD) are applied here. Despite the available software is recognized as reliable, the problem arises because the built numerical models should be validated at least partially with experimental data. There is a shortage of experimental data from real tunnels due to high costs and many organizational or formal difficulties. Some researchers use data from scaled experiments, but this leads to problems connected with scaling. The paper presents the application of two widely used software packages—Fire Dynamics Simulator (FDS) and ANSYS Fluent to reproduce some scenarios of the operation of a tunnel ventilation system for normal and emergency mode. Most of results were compared with data obtained by own full scale measurements or data available in literature. Some practical issues concerning the application of FDS and ANSYS Fluent were discussed as well.

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“…As already mentioned, a number of authors have studied the fires in road tunnels for different aspects: e.g. the scenarios of underground fire propagation [2,6,[12][13][14][15][16], temperature distribution and propagation issues in the tunnels [4,17,18], piston effect influence on the distribution of ventilation flow in underground space [11], underground fire development dynamics and their different scenarios [12,[19][20][21], propagation of smoke and toxic combustion products against the ventilation current direction [22][23][24][25] and theoretical and experimental study of critical velocities [24][25][26][27][28]. It would not be an exaggeration to say that work "The handbook of tunnel fire safety" [3] summarizes almost all-important papers published earlier.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the use of transformable elements in intelligent tunnel ventilation systems

et al. 2022

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All main and auxiliary equipment in the tunnel with an intelligent ventilation system are designed to ensure the safety. These systems “talk” and “listen” to each other, make decisions to switch on/off certain system(s) or part(s) thereof and duly inform the tunnel operator, who is authorized to the centralized control of all systems of necessity. The present article uses the numerical models to assess the efficiency of the transformable elements ensuring safe operation of the tunnels. The idea of their use is based on an artificial increase of the tunnel aerodynamic resistance by means of a flexible element, which will hamper the dissemination of combustion products, but not the movement of people through the tunnel and will help isolate clean and polluted air masses. Such resistance will be used to swiftly divide the tunnel carriageway into smaller sections what will help extinguish the fire as early as at its initial stage, prolong the evacuation time and save lives during the strong uncontrollable fires. As for the compact transformable element, it can be used in both, the operating and the planned tunnels, as it in practice does not reduce the volume of valuable underground space.

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Study of smoke back-layering length with different longitudinal fire locations in inclined tunnels under natural ventilation

Cited by 52 publications

References 39 publications

Influences of inclined tunnel ceiling on plug‐holing phenomenon and mechanical smoke exhaust efficiency in tunnel fires

Influences of inclined tunnel ceiling on plug‐holing phenomenon and mechanical smoke exhaust efficiency in tunnel fires

Some Tips on Numerical Modeling of Airflow and Fires in Road Tunnels

Analysis of the use of transformable elements in intelligent tunnel ventilation systems

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