Critical longitudinal ventilation velocity for smoke control in a tunnel induced by two nearby fires of various distances: Experiments and a revisited model

2020 ◽  
Vol 105 ◽  
pp. 103559
Author(s):  
Fei Tang ◽  
Lei Deng ◽  
Na Meng ◽  
Margaret Mcnamee ◽  
Patrick Van Hees ◽  
...  
Keyword(s):  
Smoke Control ◽  
Longitudinal Ventilation ◽  
Ventilation Velocity

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

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.

Smoke Control in Subway Tunnel Fires

2014 ◽  
Vol 638-640 ◽  
pp. 2027-2030
Author(s):  
Xiao Xiong Zha ◽  
Sheng Zeng ◽  
Yi Yan Chen ◽  
Rui Juan Jiang
Keyword(s):  
Computer Simulation ◽  
Theoretical Analysis ◽  
Critical Velocity ◽  
Simple Formula ◽  
Control Mode ◽  
Subway Tunnel ◽  
Smoke Control ◽  
Release Rates ◽  
Tunnel Fires ◽  
Ventilation Velocity

This paper concerns the smoke control modes and the critical ventilation velocity when the subway tunnel on fires. The standard for the smoke control mode is making sure the smoke exhausting in the shortest way. The critical ventilation velocity means it is just sufficient to prevent the smoke spreading upstream. The critical velocity in different heat release rates obtained though theoretical analysis and computer simulation. In the end, a simple formula to calculate the critical velocity can be fitting out.

The Study of the Confinement Velocity in the Longitudinal Ventilation Tunnel Fire

2012 ◽  
Vol 446-449 ◽  
pp. 3665-3669
Author(s):  
Ke Qing Sun ◽  
Hui Yang
Keyword(s):  
Characteristic Parameter ◽  
Experimental Models ◽  
Experimental Results ◽  
Mixed Gas ◽  
Control Effect ◽  
Smoke Control ◽  
Tunnel Fire ◽  
Longitudinal Ventilation ◽  
The Relationship ◽  
Two Sides

For the situation that the smoke exhaust vents are located on both sides of the fire source, critical ventilation velocity is not appropriate to evaluate the smoke control effect. “Confinement velocity” is proposed as the characteristic parameter to study the longitudinal ventilation by O.Vauquelin in this situation. However, there have been few studies on confinement velocity. An experimental study was carried out on two reduced scale tunnel models. The main objective is to analysis the relationship between confinement velocity and fire heat release in this situation. Helium and air in different ratio was used as the smoke, and the "cold smoke" produced by smoke generator was put into the mixed gas in order to measure the length of smoke layer. The experimental models were based on the half tunnel as flow field at two sides of fire is symmetrical. The CFD model was created on the basis of the experiment, and the results were basically accord with the experimental results. It was shown from the experimental results that the critical point of the confinement velocity is between L / H = 2 to L / H = 4 in section 1, between L / H = 1 to L / H = 2 in section 2, rather than a fixed value; Two tunnel models had similar dimensionless confinement velocity, but the dimensionless total confinement velocity was different.

scholarly journals Longitudinal Ventilation for Smoke Control of Urban Traffic Link Tunnel: Hybrid Field-network Simulation

2014 ◽  
Vol 84 ◽  
pp. 586-594 ◽  
Author(s):  
Du Tao ◽  
Yang Dong ◽  
Peng Shini ◽  
Xiao Yimin ◽  
Zhang Fan
Keyword(s):  
Network Simulation ◽  
Urban Traffic ◽  
Smoke Control ◽  
Longitudinal Ventilation ◽  
Field Network

scholarly journals Experimental and numerical study of maximum ceiling temperature in a tunnel

2019 ◽  
Vol 11 (12) ◽  
pp. 168781401989749
Author(s):  
ZP Bai ◽  
YF Li
Keyword(s):  
Heat Release ◽  
Temperature Variation ◽  
Numerical Study ◽  
Experimental Tests ◽  
Maximum Temperature ◽  
Small Scale ◽  
Experimental Conditions ◽  
Longitudinal Ventilation ◽  
Ceiling Temperature ◽  
Ventilation Velocity

Maximum ceiling temperatures in a tunnel with different ventilation velocities with three heat release fires are studied experimentally and theoretically. This article investigates the ventilation velocity effects on maximum ceiling temperature combustible materials around ignition source in tunnel fires. Several fire experimental tests are conducted with longitudinal ventilation velocity changes in a small-scale tunnel (23 m in length, 2 m in width, and 0.98 m in height), where three heat release fires (237, 340, and 567 kW) and their corresponding values in the real tunnel are 20, 30, and 50 MW, respectively. This article modifies the current temperature prediction model taking the ignition materials near the fire source into account in tunnels. Results show that the ceiling maximum temperature increases, corresponding to the burn time when other experimental conditions remain unchanged for a given fire heat level source. The ceiling temperature reduces quickly when the ventilation velocity is increased from 0.5 to 2.0 m/s. Moreover, this article proposes an equation that can be used to estimate the ceiling maximum temperature variation value with three heat release fires in tunnels. Finally, experimental results are also compared with the tunnel ceiling temperature attenuation equations established by Alpert, Heskestad, and Ingason. The equation proposed in this article appears to provide better estimates of ceiling temperature variation than the Kurioka model developed in their scaled experiments. The prediction agrees well with the experimental and measured data by the modified equations of this article.

Reduced-Scale Model Tests of Fires in Railway Tunnel and Structure Fire Safety

2010 ◽  
Vol 168-170 ◽  
pp. 2473-2476 ◽  
Author(s):  
Hong Li Zhao ◽  
Zhi Sheng Xu ◽  
Xue Peng Jiang
Keyword(s):  
Fire Safety ◽  
Numerical Models ◽  
Scale Model ◽  
Railway Tunnel ◽  
Tunnel Fires ◽  
Tunnel Fire ◽  
Longitudinal Ventilation ◽  
Overall Stability ◽  
Reduced Scale ◽  
Ventilation Velocity

The high-temperature toxic gas released by long railway tunnel fires not only causes great harm to persons, but also damages the structure of the tunnel which will reduce the overall stability of tunnel. In order to diminish the damage to tunnel structure produced by a tunnel fire, on the basis of the first extra-long underwater railway tunnel in China, some reduced-scale tests were carried out to study the distribution of smoke temperature along the tunnel ceiling, the smoke velocity and the backlayering distance with the fire size of 63KW. The longitudinal ventilation velocity and the tunnel gradient varied in these tests. The smoke temperature below the tunnel ceiling in different times and under different longitudinal ventilation velocity, the smoke velocity under the ceiling, and the backlayering distance in the presence of different ventilation velocity are acquired from the tests. The conclusions have the guiding meaning to the disaster prevention design and construction of structure fire safety in tunnel fires, and all the experimental data presented in this paper are applicable for the verification of numerical models.

Sign in / Sign up

Export Citation Format

Share Document