A simple correlation for predicting the rise time of fire-induced smoke flow in a tunnel with longitudinal ventilation

Tao, Haowen; Xu, Zhisheng; He, Lu; Liu, Qiulin; Zhao, Jiaming; Luan, Dia; Fan, Chuangang; Gong, Chenjie

doi:10.1016/j.tust.2020.103324

Cited by 17 publications

(5 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Methodsmentioning

confidence: 99%

“…In FDS, the turbulence viscosity model is expressed as equation (10). 35 Other diffusive parameters, such as the thermal conductivity and material diffusivity, are related to the turbulent viscosity by equations (11) and (12)where μ LES is the turbulence viscosity (N‧S/m 2 ), ρ is the density (kg/m 3 ), Δ is a length on the order of the size of a grid cell, utrue¯ is the average value of u at the grid cell centre (representing the LES filtered velocity at length scale Δ), C s is the Smagorinsky constant, k LES is the thermal conductivity (W/(m‧K)), C p is specific heat of air at constant pressure (kJ/(kg ‧K)), Pr is the Prandtl number, Sc is the Schmidt number and D is the diffusion coefficient (m 2 /s).…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Numerical investigation on the smoke behaviour and longitudinal temperature decay in tilted tunnel fire with portal sealing

et al. 2021

Indoor and Built Environment

View full text Add to dashboard Cite

Blocking the tunnel portal is one strategy in railway tunnel firefighting. In order to evaluate the effect of tunnel portal sealing ratio on fire behaviour, Fire Dynamics Simulator (FDS) was used to simulate tilted tunnel fire with different slope angles varying from 0% to 5%, heat release rate varying from 10 to 50 MW and sealing ratios varying from 0% to 75%. Results show that the experimental data of the temperature distribution inside the tilted tunnel were in good agreement with the simulation results. Moreover, the ceiling temperature rise decreases along the tunnel with the increase of the tunnel portal sealing ratio at initial stage and then tends to stabilize because of less oxygen supply when the heat release rate is relatively large. The maximum temperature rise decays exponentially along the tunnel ceiling with distance. The current model for temperature decay beneath the tunnel ceiling was proposed to be modified by taking the tunnel entrance sealing ratio into account. The predictions by the modified model agree well with the experimental measurement. The results could provide practical information and knowledge in ventilation system design and emergency evacuation for inclined railway tunnels.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Numerical investigation on the smoke behaviour and longitudinal temperature decay in tilted tunnel fire with portal sealing

et al. 2021

Indoor and Built Environment

View full text Add to dashboard Cite

show abstract

“…[28][29][30] Large Eddy Simulation (LES) model was used to calculate turbulence and buoyancy. 31 The default model of FDS was applied for the radiation heat transfer by solving the radiation transport equation (RTE) for a grey gas using the Finite Volume Method (FVM). 32…”

Section: Numerical Setupmentioning

confidence: 99%

“…The correlation of V* in • Q* À0. 31 and the tunnel slope is shown in Figure 7. Conducting multiple fitting processes gives equation ( 38)…”

Section: Inlet Air Velocitymentioning

confidence: 99%

A simplified calculation method on the smoke back-layering length and inlet air velocity in a tilted tunnel fire without shaft

et al. 2022

Indoor and Built Environment

View full text Add to dashboard Cite

In a tilted tunnel fire, the inlet air velocity caused by the stack effect at the entrance of the tunnel would be beneficial to smoke control whether the longitudinal ventilation system is used or not. This paper conducted the simulation to investigate the smoke spread behaviours caused by fires in tilted tunnels with natural ventilation. The expression of the smoke back-layering length and the inlet air velocity induced by fires were deduced in the tilted tunnel fire scenarios by the method of dimensional analysis. The effect of various tunnel slopes (5–15%) on the smoke behaviours characteristics and the inlet air velocity were specifically considered. The proposed correlation reveals that the dimensionless back-layering length is independent of the heat release rate (HRR) and its relationship with the tunnel slope is proportional to −1.96 power. The established equation reveals that the dimensionless inlet air velocity is proportional to 0.31 power of the dimensionless HRR and it increases exponentially with the tunnel slope. This research on this topic may contribute to optimize the application of natural ventilation systems or mechanical ventilation in tilted tunnels.

show abstract

“…Tunnels are important construction for solving traffic jams and others transportation problems, and many tunnels have been built around the world 1 . However, once a fire occurs in the tunnel, the fire‐induced smoke will spread rapidly along the tunnel 2‐4 . The large amount of smoke and toxic gases will be a threat to the trapped people in the tunnel fire 5‐7 .…”

Section: Introductionmentioning

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

Self Cite

View full text Add to dashboard Cite

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.

show abstract

A simple correlation for predicting the rise time of fire-induced smoke flow in a tunnel with longitudinal ventilation

Cited by 17 publications

References 29 publications

Numerical investigation on the smoke behaviour and longitudinal temperature decay in tilted tunnel fire with portal sealing

Numerical investigation on the smoke behaviour and longitudinal temperature decay in tilted tunnel fire with portal sealing

A simplified calculation method on the smoke back-layering length and inlet air velocity in a tilted tunnel fire without shaft

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

Contact Info

Product

Resources

About