Research on the effect of ceiling centralized smoke exhaust system with air curtains on heat confinement and plug-holing phenomenon in tunnel fires

Chen, Zhiying; Liu, Zhixiang; Huang, Linqi; Guo-qing, Niu; Yan, Jingyi; Wang, Jiajun

doi:10.1016/j.psep.2022.11.054

Cited by 12 publications

(5 citation statements)

References 39 publications

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“…where D* is the characteristic diameter of the fire source, m; Q is the fire source power, KW; ρ ∞ is the density of air, kg/m 3 ; C p is the specific heat capacity of constant pressure air, J/(kg• • C); T ∞ is the ambient temperature, which is set to 293 K; g is the gravitational acceleration, m/s 2 . After calculation, the characteristic diameter of the fire source in this example is 0.35 m. Based on previous research findings [24,25], when the characteristic diameter of the fire source is 4-16 times the grid size, the accuracy of the simulation results is acceptable. The grid size should be set as 0.02-0.09 m. However, due to computer performance limitations, simulation cannot be completed when the grid size is 0.06 m. Therefore, a grid sensitivity study was conducted using grid sizes of 0.07 m, 0.09 m, 0.1 m, 0.15 m, 0.2 m, and 0.25 m. The temperature change of the end thermocouple serves as a reference for grid sensitivity analysis.…”

Section: Numerical Modelmentioning

confidence: 65%

“…After calculation, the characteristic diameter of the fire source in t m. Based on previous research findings [24][25], when the characteris fire source is 4-16 times the grid size, the accuracy of the simulation re The grid size should be set as 0.02-0.09 m. However, due to computer tations, simulation cannot be completed when the grid size is 0.06 m sensitivity study was conducted using grid sizes of 0.07 m, 0.09 m, 0.1 and 0.25 m. The temperature change of the end thermocouple serves grid sensitivity analysis. The spacing of smoke screens is set to 1 m simulation.…”

Section: Numerical Modelmentioning

confidence: 99%

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Research on the Optimal Spacing of Multiple Roof Smoke Blocking Structures in a Long Corridor

Wu,

Wang,

Shao

et al. 2024

Fire

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In a long and narrow corridor, the installation of roof smoke blocking structures is a measure to slow down the spread of fire smoke. When employing multiple smoke blocking structures, the spacing between these structures is a critical parameter that needs to be considered for optimal effectiveness. This paper analyzes the smoke blocking performance of double structures at different spacing and measures the smoke flow velocity both upstream and downstream of the double structures. According to the analysis of the smoke velocity vector obtained from numerical simulation, the smoke can be divided into three zones based on the flow state of the smoke after passing through the front smoke screen structure, namely the vortex zone, surge wave zone, and steady flow zone. When the rear smoke screen is located in the surge zone, the smoke blocking effect is optimal. Analysis of the morphology of the smoke layer indicates that the length of the vortex region is directly proportional to the upstream smoke flow velocity. The numerical and experimental results both indicate that an excessively large or small spacing between the structures fails to achieve optimal smoke control effectiveness. When the spacing is within an optimal range, the smoke velocity is the lowest. Finally, using a real architectural corridor as a case background, this paper presents a design example of roof smoke blocking structures. In order to arrange as many smoke blocking structures as possible, an appropriate spacing between the structures should be slightly larger than the vortex region. The smoke control effectiveness of multiple roof structures was validated through numerical simulation. As a result, the time required for smoke to pass through the corridor increases by 110 s.

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Section: Numerical Modelmentioning

confidence: 65%

Section: Numerical Modelmentioning

confidence: 99%

Research on the Optimal Spacing of Multiple Roof Smoke Blocking Structures in a Long Corridor

Wu,

Wang,

Shao

et al. 2024

Fire

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“…Air curtain system [66,67] The air curtain system can artificially control the wind speed and temperature of the air entering the tunnel to increase the temperature inside the tunnel cavity, which can reduce the severity of frost damage to a certain extent. However, this system is in the same research stage as ground source heat pumps and has not yet been applied on a large scale to insulate tunnels in cold regions.…”

Section: Active Measuresmentioning

confidence: 99%

Recent Progress in the Cracking Mechanism and Control Measures of Tunnel Lining Cracking under the Freeze–Thaw Cycle

Yuan,

Ma,

Liu

et al. 2023

Sustainability

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With the rapid increase in the scale and number of tunnels in cold regions, the frost damage problems, such as cracking of the lining structure under the action of freeze–thaw cycles are becoming increasingly prominent. This review article collects and sorts out the frost damage phenomena that occur in the lining structure of tunnels in cold regions under the action of freezing and thawing cycles, classifies the frost damage phenomena into structural frost damage and non-structural frost damage, and proposes that the research on the mechanism of lining frost damage and its prevention measures should focus on lining cracking. According to the damage degree of the freeze–thaw cycle to the lining structure and its influence on tunnel operation, the cracking mode and cracking stage of lining are introduced. The analysis focuses on the mechanism of cracking in lining structures subjected to freeze–thaw cycles, considering the external force caused by frost heaving, the alteration of mechanical properties in lining concrete, and the internal changes in the microstructure of the concrete. Additionally, the factors that contribute to the occurrence of lining cracking are summarized. Based on this, corresponding control measures have been organized to provide reference for the development of cracking of the lining structure under the action of freeze–thaw cycle.

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“…Typically, when the cell size δ x ranges between 0.06 D* and 0.25 D* [33], the accuracy of the calculation results can be ensured. Therefore, the characteristic diameter D* was 1.27 m, and the range of the cell size δ x was 0.08 m~0.32 m.…”

Section: Grid Divisionmentioning

confidence: 99%

Sensitivity Analysis of Influencing Factors of Fire Smoke Transport on Subway Station Platforms

Song,

Chen,

et al. 2023

Fire

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This paper investigates the sensitivity of factors influencing the transport of smoke in subway station fires by developing a three-dimensional physical model of a subway station using Building Information Modeling (BIM) technology and importing it into Fire Dynamics Simulator (FDS) software for numerical simulation. The orthogonal test method analyzes the effects of four common factors on temperature, CO concentration, and visibility. These factors are the mode of opening the screen door, the number of smoke vents opened, the number of smoke barriers, and the wind speed of the smoke vents. The results show that the smoke control system and the building structure influence smoke transport in subway stations, while the temperature and CO concentration gradually decrease as the distance from the fire source increases. In addition, the mode of opening the screen door is the most significant factor influencing temperature, CO concentration, and visibility using range and variance analysis. Moreover, the sensitivity analysis indicates that the optimal combination of all factors can significantly enhance the smoke exhaust efficiency. Compared with the average, the temperature optimal combination increases the smoke exhaust efficiency by 20.8%, CO concentration by 56.59%, and visibility by about 13.41%. This study provides a foundation for optimizing smoke control systems and formulating personnel evacuation strategies in subway stations.

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Research on the effect of ceiling centralized smoke exhaust system with air curtains on heat confinement and plug-holing phenomenon in tunnel fires

Cited by 12 publications

References 39 publications

Research on the Optimal Spacing of Multiple Roof Smoke Blocking Structures in a Long Corridor

Research on the Optimal Spacing of Multiple Roof Smoke Blocking Structures in a Long Corridor

Recent Progress in the Cracking Mechanism and Control Measures of Tunnel Lining Cracking under the Freeze–Thaw Cycle

Sensitivity Analysis of Influencing Factors of Fire Smoke Transport on Subway Station Platforms

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