scholarly journals A study on the temperature profile of bifurcation tunnel fire under natural ventilation

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0262546
Author(s):  
Jianlong Zhao ◽  
Yanfeng Li ◽  
Junmei Li ◽  
Jiaxin Li
Keyword(s):  
Temperature Profile ◽  
Natural Ventilation ◽  
Prediction Models ◽  
Longitudinal Direction ◽  
Numerical Code ◽  
Maximum Temperature ◽  
Tunnel Fire ◽  
Fire Engineering ◽  
Temperature Decay ◽  
Fire Scenarios

This study simulated a series of bifurcation tunnel fire scenarios using the numerical code to investigate the temperature profile of bifurcation tunnel fire under natural ventilation. The bifurcation tunnel fire scenarios considered three bifurcation angles (30°, 45°, and 60°) and six heat release rates (HRRs) (5, 10, 15, 20, 25, and 30 MW). According to the simulation results, the temperature profile with various HRRs and bifurcation angles was described. Furthermore, the effects of bifurcation angles and HRRs on the maximum temperature under the bifurcation tunnel ceiling and the temperature decay along the longitudinal direction of the branch were investigated. According to the theoretical analysis, two prediction models were proposed. These models can predict a bifurcation tunnel fire’s maximum temperature and longitudinal temperature decay in the branch. The results of this study could be valuable for modelling a bifurcation tunnel fire and benefit the fire engineering design of bifurcation tunnels.

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

2021 ◽  
pp. 1420326X2110348
Author(s):  
Jiaxin Li ◽  
Yanfeng Li ◽  
Junmei Li ◽  
Quan Yang
Keyword(s):  
Heat Release ◽  
Heat Release Rate ◽  
Release Rate ◽  
Temperature Rise ◽  
Ventilation System ◽  
Emergency Evacuation ◽  
Maximum Temperature ◽  
Tunnel Fire ◽  
Temperature Decay ◽  
Tunnel Portal

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.

Potential Insights from Performance-Based Design of Fire Protection in Tall Buildings

2019 ◽  
Author(s):  
Pierre Ghisbain ◽  
Jenny Sideri ◽  
Reyhaneh Abbasi ◽  
Luciana Balsamo ◽  
Reza Imani ◽  
...  
Keyword(s):  
Fire Protection ◽  
Mechanical Response ◽  
Tall Buildings ◽  
Element Model ◽  
Fire Effects ◽  
Design Fire ◽  
Fire Engineering ◽  
Fire Scenarios ◽  
Fire Loading ◽  
The Impact

<p>Analysis of the structural performance under realistic fire scenarios makes Performance Based Fire Engineering (PBFE) particularly suited to design fire protection of tall buildings. In this paper, the impact of using the PBFE method is studied using a standard tall building as an example. The parametric temperature- time curves recommended in Eurocode 1 are used to define the fire loads. The thermal and mechanical response of the building to the imposed fire loading is subsequently analyzed by means of a finite element model of the mixed-use tower. Particular care is devoted to analyzing the performance of a steel truss at a transfer level, to study potential global effects of a local fire, effects that are not studied or understood within the prescriptive design framework.</p>

The Polytropic Approach in Modelling Compressible Flows Through Constant Cross-Section Pipes

2021 ◽  
Author(s):  
Alessandro Ferrari ◽  
Oscar Vento ◽  
Tantan Zhang
Keyword(s):  
Steady State ◽  
Cross Section ◽  
Compressible Flows ◽  
Analytical Formula ◽  
Local Maximum ◽  
Wall Friction ◽  
Numerical Code ◽  
Maximum Temperature ◽  
Constant Cross Section ◽  
Polytropic Exponent

Abstract A compressible flow with wall friction has been predicted in a constant cross-section duct by means of a barotropic modelling approach, and new analytical formulas have been proposed that also allow any possible heat transfer to the walls to be taken into account. A comparison between the distributions of the steady-state flow properties, pertaining to the new formulas, and to those of a classic Fanno analysis has been performed. In order to better understand the limits of the polytropic approach in nearly chocked flow applications, a numerical code, which adopts a variable polytropic coefficient along the duct, has been developed. The steady-state numerical distributions along the pipe, obtained for either a viscous adiabatic or an inviscid diabatic flow by means of this approach, coincide with those of the Fanno and Rayleigh models for Mach numbers up to 1. A constant polytropic exponent can be adopted for a Fanno flow that is far from choking conditions, while it cannot be adopted for the simulation of a Rayleigh flow, even when the flow is not close to choking conditions. Finally, under the assumption of diabatic flows with wall friction, the polytropic approach, with a constant polytropic exponent, is shown to be able to accurately approximate cases in which no local maximum is present for the temperature along the duct. The Mach number value at the location where the local maximum temperature possibly occurs has been obtained by means of a new analytical formula.

A Multi-Dwell Temperature Profile Design for the Cure of Thick CFRP Composite Laminates

2021 ◽  
Author(s):  
Wenchang Zhang ◽  
Yingjie Xu ◽  
Xinyu Hui ◽  
Weihong Zhang
Keyword(s):  
Temperature Profile ◽  
Composite Laminates ◽  
Optimization Method ◽  
Maximum Temperature ◽  
Nsga Ii ◽  
Multi Objective ◽  
Optimization Result ◽  
Design Variables ◽  
Cure Time ◽  
Thick Laminates

Abstract This paper develops a multi-objective optimization method for the cure of thick composite laminates. The purpose is to minimize the cure time and maximum temperature overshoot in the cure process by designing the cure temperature profile. This method combines the finite element based thermo-chemical coupled cure simulation with the non-dominated sorting genetic algorithm-II (NSGA-II). In order to investigate the influence of the number of dwells on the optimization result, four-dwell and two-dwell temperature profiles are selected for the design variables. The optimization method obtains successfully the Pareto optimal front of the multi-objective problem in thick and ultra-thick laminates. The result shows that the cure time and maximum temperature overshoot are both reduced significantly. The optimization result further illustrates that the four-dwell cure profile is more e ective than the two-dwell, especially for the ultra-thick laminates. Through the optimization of the four-dwell profile, the cure time is reduced by 51.0% (thick case) and 30.3% (ultra-thick case) and the maximum temperature overshoot is reduced by 66.9% (thick case) and 73.1% (ultra-thick case) compared with the recommended cure profile. In addition, Self-organizing map (SOM) is employed to visualize the relationships between the design variables with respect to the optimization result.

Simulation and Modelling in Fire Safety

2020 ◽  
pp. 232-262
Author(s):  
Tomaz Hozjan ◽  
Kamila Kempna ◽  
Jan Smolka
Keyword(s):  
Virtual Reality ◽  
Fire Safety ◽  
Rapid Development ◽  
Fire Spread ◽  
Practical Training ◽  
Smoke Movement ◽  
Fire Engineering ◽  
Limited Budget ◽  
Fire Scenarios ◽  
In Fire

Actual and future concerns in fire safety in buildings and infrastructure are challenging. Modern technologies provide rapid development in area of fire safety, especially in education, training, and fire-engineering. Modelling as a tool in fire-engineering provides possibility to design specific fire scenarios and investigate fire spread, smoke movement or evacuation of occupants from buildings. Development of emerging technologies and software provides higher possibility to apply these models with interactions of augmented and virtual reality. Augmented reality and virtual reality expand effectivity of training and preparedness of first (fire wardens) and second (firefighters) responders. Limitations such as financial demands, scale and scenarios of practical training of first and second responders are much lower than in virtual reality. These technologies provide great opportunities in preparedness to crisis in a safety way with significantly limited budget. Some of these systems are already developed and applied in safety and security area e.g. XVR (firefighting, medical service).

Temperature profile of fire-induced smoke in node area of a full-scale mine shaft tunnel under natural ventilation

2017 ◽  
Vol 110 ◽  
pp. 382-389 ◽  
Author(s):  
Chang Liu ◽  
Maohua Zhong ◽  
Congling Shi ◽  
Peihong Zhang ◽  
Xiangliang Tian
Keyword(s):  
Temperature Profile ◽  
Natural Ventilation ◽  
Full Scale ◽  
Mine Shaft
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