Study of Fire Smoke Flow of Tunnel at Different Longitudinal Ventilation

2012 ◽  
Vol 226-228 ◽  
pp. 1472-1475
Author(s):  
Pei Pei Yang ◽  
Xiao Lu Shi ◽  
Bi Ming Shi
Keyword(s):  
Flow Resistance ◽  
Reverse Flow ◽  
Ventilation System ◽  
Gas Temperature ◽  
Smoke Control ◽  
Smoke Flow ◽  
Longitudinal Ventilation ◽  
Smoke Spread ◽  
Fire Smoke ◽  
Safety Evacuation

Once the tunnel fires happened, it will cause a major accident. And the smoke control of the runnel is important to fire prevention. A numerical simulation of the fire smoke flow in the tunnel model is presented by using FDS. The influence of different longitudinal ventilation on fire smoke flow of tunnel is obtained. And providing theory basis for tunnel ventilation system design, smoke spread control and safety evacuation. The results shown that in order to avoid reverse-flow and extend the time of smoke at the top of tunnel, the longitudinal speed should be controlled in 3.4 m/s; because of the role of longitudinal ventilation, smoke flow resistance and longitudinal ventilation generated by the effect of smoke flow resistance make the gas temperature first rise and then down.

Study on the smoke propagation characteristics of metro tunnel fire under the effects of piston wind

2021 ◽  
pp. 1420326X2199842
Author(s):  
Fei Wang ◽  
Fang Liu ◽  
Imad Obadi ◽  
Miaocheng Weng
Keyword(s):  
Wind Speed ◽  
Bernoulli Equation ◽  
Propagation Characteristics ◽  
Control Effect ◽  
Smoke Control ◽  
Tunnel Fire ◽  
Longitudinal Ventilation ◽  
Smoke Spread ◽  
Fire Smoke ◽  
Metro Tunnel

Metro trains running in tunnels cause piston wind, and when a metro train stops in a tunnel due to a fire, the effect of the piston wind on smoke propagation characteristics cannot be ignored. In this paper, a theoretical model based on the unsteady flow theory of the Bernoulli equation was established to describe the change in piston wind speed under fire conditions. The characteristics of the smoke propagation in tunnel fires under the effect of the piston wind were analysed by means of numerical simulation. The result indicates that the piston wind has a significant effect on the characteristics of smoke distribution. In a longitudinally ventilated tunnel, whether the direction of piston wind is the same as that of longitudinal ventilation could seriously affect the control of fire smoke. When the direction is the same, the piston wind could enhance the smoke control effect of the longitudinal ventilation. Otherwise, the smoke control effect could be significantly diminished, and the smoke control by the critical wind speed of longitudinal ventilation would fail. The findings could contribute to a better understanding of the characteristics of tunnel fire to control smoke spread under the influence of piston wind.

Numerical Analysis on the Effect of Thermal Insulation of Closure on Fire Smoke Spread Rate in Building's Corridor

2014 ◽  
Vol 513-517 ◽  
pp. 2635-2638
Author(s):  
Xuan Wei Peng
Keyword(s):  
Numerical Analysis ◽  
Thermal Insulation ◽  
Air Temperature ◽  
Spread Rate ◽  
Smoke Flow ◽  
External Insulation ◽  
Flow Prediction ◽  
Smoke Spread ◽  
Fire Smoke ◽  
Fire Ignition

The corridor is an important way of evacuation and rescue in building fire. The fire smoke flow prediction software developed successfully was applied to simulate a building with a 28.8 meters long corridor to investigate the effect of the different thermal insulation on fire smoke spread rate. Two representative thermal insulation, external insulation and internal insulation were compared. In 3600s fire time, air temperature in the corridor of external insulation is much lower than that of internal insulation. The air temperature gap gets narrowed between the two insulation methods in the corridor with the prolongation of fire time. Temperature difference increases as the distance increase from the fire ignition place. The corridor gets unsafe of internal insulation in 7 minute since fire ignition, while about half the length of the corridor stay secure of external insulation in 10 minutes since fire ignition. That implies more available safe egress time can be gained with external insulation than internal insulation. Smoke spread rate was numerically compared based on the air temperature variation. Smoke spread rate of internal insulation is much higher than that of external insulation and the corresponding ratio is 1.732:1.

scholarly journals Numerical simulation on the characteristics of smoke exhaust effect with different sets of smoke vent in deep buried inclined channel fire

2021 ◽  
Vol 252 ◽  
pp. 02050
Author(s):  
Lu Yuhan ◽  
Weng Miao cheng ◽  
Liu Fang
Keyword(s):  
Control Effect ◽  
Smoke Control ◽  
Metro Station ◽  
Thermal Buoyancy ◽  
Average Temperature ◽  
Fire Source ◽  
Smoke Spread ◽  
Fire Smoke ◽  
Fire Characteristics ◽  
Better Than

Deep buried metro stations require longer and more inclined exit passages to connect with the outside. The fire characteristics of these inclined and narrow passages are significantly different from those of above-ground or shallow buried metro station exit passages, and at the same time fires in those inclined channels have a greater risk. This paper takes a channel of deep buried tunnel station in Chongqing as an example and simplifies the actual passage to establish a 3D model to study the smoke spread characteristics along the passage with different smoke vent characteristics including shape and location by FDS, as well as temperature distribution characteristic under different working conditions. The results show that: after a fire, smoke will spread upwards rapidly under the action of thermal buoyancy, and mechanical smoke exhaust plays a certain role in controlling smoke, which is more obvious at the beginning of the fire; there are differences in the smoke exhaust efficiency of different smoke extraction openings shape, but the differences are small, and square smoke vents have a slightly better effect on smoke control than other shapes of smoke vents; changing the location of smoke outlets has a greater impact on the environment in the tunnel. When the smoke vent is located directly above the fire source, the mechanical smoke control effect is significantly better than other positions, and as the distance between smoke vent and fire source increases, the average temperature along the passage increases. At the same time, because of the pressure difference after the fire, the emergency staircase and the upstream of the fire source are basically unaffected by smoke.

Effect Analysis of Different Exhaust Velocity on Fire Smoke Control in Subway Tunnel

2012 ◽  
Vol 424-425 ◽  
pp. 1224-1227
Author(s):  
Xin Han ◽  
Xiao Ming Gao ◽  
Bei Hua Cong
Keyword(s):  
Cfd Simulation ◽  
Simulation Analysis ◽  
Simulation Method ◽  
Subway Tunnel ◽  
Control Effect ◽  
Smoke Control ◽  
Effect Analysis ◽  
Longitudinal Ventilation ◽  
Fire Smoke ◽  
Ventilation Velocity

Taking a subway tunnel as the research object and based on the CFD simulation method, this paper adopts a large eddy simulation analysis software FDS to simulate and analyze the effect of exhaust velocity on fire smoke control under the condition of the same longitudinal ventilation velocity in subway tunnel. The simulated results can provide some reference to design institutes in the selection of exhaust fan. While the longitudinal ventilation velocity set as 1m/s, the simulation results demonstrate that a quite good smoke control effect could be achieved when the exhaust velocity reaches 5 m/s in the smoke exhaust duct

A Study on Tunnel Smoke Control Strategies by Experiment and Numerical Simulation

2011 ◽  
Vol 402 ◽  
pp. 864-867
Author(s):  
Xiao Yang Liu ◽  
Jing Yan Zhang ◽  
Yan Feng Li ◽  
Li Li Zhang ◽  
Jin Feng Yuan
Keyword(s):  
Scale Model ◽  
Road Tunnel ◽  
Smoke Control ◽  
Fire Control ◽  
Fire Dynamics ◽  
Tunnel Fire ◽  
Longitudinal Ventilation ◽  
Fire Smoke ◽  
Smoke Layer ◽  
Layer Velocity

In order to meet the need of the study on the tunnel fire safety system, taking the tunnel laboratory bench in the key laboratory of the university of science and technology of China as the object, this paper does a scale model experiment on the tunnel fire, and uses the Fire Dynamics Simulator（FDS）software to simulate fire smoke layer velocity under different longitudinal ventilation control, by comparing the experimental and simulation results, this paper not only gives the variation law of the tunnel fire smoke layer velocity under different longitudinal ventilation speed, but also proposes the concept of the smoke stratification critical wind speed , which will provide some references for the road tunnel fire control, rescue and evacuation.

scholarly journals Model tests of fire smoke control effects in highway tunnels

2020 ◽  
Vol 72 (09) ◽  
pp. 781-792
Keyword(s):  
Temperature Distribution ◽  
Flow Pattern ◽  
Similarity Criterion ◽  
Model Tests ◽  
Smoke Control ◽  
Airflow Velocity ◽  
Smoke Flow ◽  
Longitudinal Temperature ◽  
Fire Smoke

In this work, a typical tunnel 150 m in length is selected and modelled at a scale of 1:15 to assess its effects on smoke control. A total of 32 model tests on smoke flow pattern and longitudinal temperature distribution have been carried out based on the Froude similarity criterion. The results show that smoke control is affected by three factors, namely, the longitudinal airflow velocity, number of opened smoke-exhaust dampers, and fire power, out of which the longitudinal airflow velocity has the greatest effect on smoke control.

Analysis of Fire Smoke Control System of under Construction Tunnel

2012 ◽  
Vol 594-597 ◽  
pp. 1245-1250
Author(s):  
Jia Yun Sun ◽  
Zheng Fang ◽  
Jian Ping Yuan
Keyword(s):  
Control System ◽  
Ventilation Rate ◽  
Smoke Control ◽  
Smoke Movement ◽  
Smoke Spread ◽  
Fire Smoke ◽  
Under Construction ◽  
Smoke Control System ◽  
Distinguishing Features ◽  
Ventilation Systems

Compared with operated tunnel, one of the distinguishing features of a tunnel during construction is its single-ended geometry. The direction of fire smoke movement is the same as the direction for worker to evacuate the tunnel. This paper calculates fire-induced conditions, including temperature, smoke movement and visibility, which are influenced by two different ventilation systems. According to the simulation, when the fire located at bottom of tunnel, forced extraction is more effective; when the fire located at middle of tunnel, forced injection can protect workers in tunnel. Besides，increasing ventilation rate can control smoke spread effectively.

Numerical Simulation on Fire Smoke Flow with Jet Fans in an Underground Garage

2011 ◽  
Vol 374-377 ◽  
pp. 534-537
Author(s):  
Ying Wang ◽  
Bi Ming Shi ◽  
Chao Min Mu
Keyword(s):  
Numerical Simulation ◽  
Ventilation System ◽  
Smoke Flow ◽  
Acceptable Range ◽  
Fire Smoke

With the aim of evaluating capabilities of a ventilation system with jet fans to control fire smoke in an underground garage, we carried out a set of FDS simulation. According to the results, temperature and soot density of fire has reduced within an acceptable range. We believe that the ventilation system based on the jet fans has indeed controlled fire smoke effectively, thereby we have enough time for safety rescue.

scholarly journals Investigation on the Effect of Platform Height on Smoke Characteristics of Fire Scenarios for Subway Stations

2021 ◽  
Vol 13 (19) ◽  
pp. 10584
Author(s):  
Desheng Xu ◽  
Yanfeng Li ◽  
Junmei Li ◽  
Jin Zhang ◽  
Jiaxin Li
Keyword(s):  
Early Stage ◽  
Control Design ◽  
Exhaust System ◽  
Maximum Temperature ◽  
Smoke Control ◽  
Smoke Spread ◽  
Fire Scenarios ◽  
Ceiling Height ◽  
Subway Stations ◽  
Safety Evacuation

In this study, three full-scale experiments and a series of numerical simulations were conducted to investigate the influence of subway platform height and atrium ceiling height of subway stations on smoke control by mechanical exhausting systems. The smoke temperature variation with time, maximum temperature distribution, and smoke stratification were discussed. Results showed that the atrium had capacity to store smoke, especially at the early stage of smoke spread. However, the efficiency of smoke extraction did not increase simply with the rise in platform height and atrium ceiling height, and favorable smoke exhaust velocity was crucial for smoke elimination. The optimal smoke exhaust velocity was studied by numerical simulation and it was found that the area of smoke diffusion in subway stations with a higher platform was significantly smaller under the optimal smoke exhaust velocity. In addition, a prediction model of optimal smoke exhaust velocity with subway platform height was proposed. This study could provide on-site data and smoke spread characteristics for smoke control design, operation, and, significantly, guide safety evacuation of the exhaust system of subway stations.

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