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.

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.

Numerical Study of Smoke Control for Underground Platform in a High-Speed Railway Station

2012 ◽  
Vol 256-259 ◽  
pp. 2803-2812 ◽  
Author(s):  
Hua Yang ◽  
Richard Yuen ◽  
He Ping Zhang
Keyword(s):  
Urban Space ◽  
High Speed ◽  
Numerical Study ◽  
Exhaust System ◽  
Cfd Modeling ◽  
Smoke Control ◽  
Railway Station ◽  
High Speed Railway ◽  
Fire Engineering ◽  
Smoke Spread

Smoke control for the underground platform of a high-speed railway station was investigated. Nowadays, the development of high-speed railway in China is rapid. In order to economize valuable urban space and to realize the convenient interchange to the subway, some of the high-speed railway station platforms and transfer halls are set underground. It is difficult and uneconomic to achieve static ventilation in the underground platform. Therefore, The mechanical smoke control system is the most feasible and most reliable method to ensure the fire safety of the underground platform. How to protect the evacuation stairs free from the threat of fire-induced smoke is a major concern of smoke control in the underground platform. An underground island platform and underground waiting and transfer halls of an under construct high-speed railway station in south China are reconstructed in this paper. Three smoke control modes based on mechanical ventilation, namely mechanical air makeup, pressurized air supply for stairwell and air curtain, are numerically simulated by Computational Fluid Dynamics (CFD) method. The distribution of smoke, temperature, and CO in the platform and influences of them on evacuation staircases are computed and analyzed. The effect of fire location in smoke spread are explored in our research. This study based on CFD modeling enables the improvement of the design and operation of smoke control and exhaust system for underground high-speed railway station. The results are applicable to practical fire engineering designs for underground high-speed railway station platform.

scholarly journals Numerical Simulations for a Typical Train Fire in China

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
W. K. Chow ◽  
K. C. Lam ◽  
N. K. Fong ◽  
S. S. Li ◽  
Y. Gao
Keyword(s):  
Numerical Simulations ◽  
Heat Release ◽  
Fire Safety ◽  
Input Parameter ◽  
Transport Systems ◽  
Fuel Vapor ◽  
Design Fire ◽  
Smoke Spread ◽  
Fire Scenarios ◽  
Subway Stations

Railway is the key transport means in China including the Mainland, Taiwan, and Hong Kong. Consequent to so many big arson and accidental fires in the public transport systems including trains and buses, fire safety in passenger trains is a concern. Numerical simulations with Computational Fluid Dynamics on identified fire scenarios with typical train compartments in China will be reported in this paper. The heat release rate of the first ignited item was taken as the input parameter. The mass lost rate of fuel vapor of other combustibles was estimated to predict the resultant heat release rates by the combustion models in the software. Results on air flow, velocity vectors, temperature distribution, smoke layer height, and smoke spread patterns inside the train compartment were analyzed. The results are useful for working out appropriate fire safety measures for train vehicles and determining the design fire for subway stations and railway tunnels.

scholarly journals Numerical Study of Smoke Propagation in a Simulated Fire in a Wagon Within a Subway Tunnel

2008 ◽  
Author(s):  
Felipe Vittori ◽  
Luis Rojas-Solo´rzano ◽  
Armando J. Blanco ◽  
Rafael Urbina
Keyword(s):  
Numerical Study ◽  
Ventilation System ◽  
Road Tunnel ◽  
Subway Tunnel ◽  
Longitudinal Ventilation ◽  
Emergency Ventilation ◽  
Tunnel Section ◽  
Fire Scenarios ◽  
Subway Stations ◽  
Set Up

This work deals with the numerical (CFD) analysis of the smoke propagation during fires within closed environments. It is evaluated the capacity of the emergency ventilation system in controlling the smoke propagation and minimizing the deadly impact of an eventual fire in a wagon within the Metro de Caracas subway tunnel on the passengers safety. For the study, it was chosen the tunnel section between Teatros and Nuevo Circo subway stations, which consists of two parallel independent twin tunnels, connected through a transverse passage. The tunnels are provided by a longitudinal ventilation system, integrated by a set of reversible fans located at both ends of the tunnels. Three stages were considered in the study: (a) Model set up; (b) Mesh sensitivity analysis; (c) Validation of the physical-numerical parameters to be used in the numerical model; and (d) Simulation of fire scenarios in Metro de Caracas subway stations. Stages (b)–(c), aimed to testing and calibrating the CFD tool (ANSYS-CFX10™), focused on reproducing experimental data from Vauquelin and Me´gret [1], who studied the smoke propagation in a fire within a 1:20 scale road tunnel. Stage (d) critical scenarios were established via a preliminary discussion with safety experts from Metro de Caracas, in order to reduce the computer memory and the number of simulations to be performed. The analyses assessed the reliability of escape routes and alternative paths for the evacuation of passengers. Additionally, the smoke front movement was particularly computed, as a function of time, in order to determine the possible presence of the “backlayering” phenomenon [5]. Results demonstrate the strengths and weaknesses of the current ventilation system in the event of a fire in the subway tunnel, and suggest new strategies to address this potentially lethal event to minimize the risks for passengers.

On the Use of Solid Curtains Near Smoke Extraction Vents to Control Smoke Spread Resulting From Fire in Road Tunnels

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Taher Halawa
Keyword(s):  
High Temperature ◽  
Release Rate ◽  
Control Strategy ◽  
Smoke Control ◽  
Smoke Spread ◽  
Peak Heat Release Rate ◽  
Road Tunnels ◽  
Low Visibility ◽  
Temperature Levels ◽  
Fire Accidents

Abstract The effectiveness of the smoke control strategy plays an important role in increasing safety levels when fire accidents occur in road tunnels. This paper introduces clarifications about how the efficiency of smoke extraction control using solid curtains can be increased by placing smoke extraction vents close to the solid curtains. The effect of adding a solid curtain with different heights and at various positions relative to a smoke extraction vent was studied in this paper. A 14.3% increase in the vent flowrate occurs at the time corresponding to the fire peak heat release rate when the distance between the solid curtain and the vent is equivalent to 90% of the tunnel height and when the solid curtain height is equal to 16% of the tunnel height. High temperature and low visibility conditions occur near the solid curtain at the smoke-trapped area when the smoke curtain height exceeds 40% of the tunnel height. Using a solid curtain positioned far away from the vent with a distance equals to 90% of the tunnel height and with a height in the range from 16% to 30% of the tunnel height achieves the best results in terms of suppression of smoke spread and attaining acceptable visibility and temperature levels at the region where the smoke is trapped by the solid curtain.

scholarly journals Abrasion-Resistant and Temperature Control of Lining Concrete for Large-Sized Spillway Tunnels

2020 ◽  
Vol 10 (21) ◽  
pp. 7614
Author(s):  
Qiang Yao ◽  
Shunchao Qi ◽  
Faming Wu ◽  
Xingguo Yang ◽  
Hongtao Li
Keyword(s):  
Fly Ash ◽  
Short Duration ◽  
Temperature Control ◽  
Performance Test ◽  
Early Stage ◽  
High Flow ◽  
Maximum Temperature ◽  
Measured Temperature ◽  
Maximum Temperature Difference ◽  
Morphological Effect

With regard to the high anti-scouring and abrasion-resistant performance requirements and great temperature control difficulties of lining concrete for large-sized spillway tunnels, in this study, a performance test was conducted on anti-scouring and abrasion-resistant concrete. The finite element method was used to analyze the temperature change rules of sidewall C9050 (design strength of concrete is 50 MPa at 90 days) lining concrete for the spillway tunnel. Further, a new cooling measure was proposed for adopting “early-throughput, high-flow and short-duration”. As indicated by the results of this study, fly ash could reduce water consumption and micro-cracks via its “morphological effect”. Silica fume could improve the early strength of cement concrete and make up for the strength loss caused by fly ash. Polyvinyl alcohol (PVA) fiber could enhance concrete durability. The doping of these three additives reinforced the strength and abrasion resistance of concrete. The results showed that the temperature of the lining concrete presented a change trend of “rapid increase first, followed by a slow decrease”. The peak temperature was reached roughly 2 days after casting. In addition, properly increasing throughput flow or decreasing throughput temperature in the early stage of casting could significantly reduce the highest temperature and maximum temperature difference of concrete. Based on the results from the numerical simulation of temperature control effect, it was proposed to adopt “early-throughput, high-flow, and short-duration” for temperature control and cracking prevention. Specifically, within 2 days after casting, cooling water at roughly 12 °C was guided in at a flow of approximately 3.5 m3/h. Within 3–7 days after casting, river water at around 17 °C was guided in at a flow rate of approximately 1.8 m3/h. After 7 days, the cooling effect can be well achieved by only using the surface flowing water for curing. According to the field monitoring data, the changes in measured temperature were basically consistent with those from numerical simulations, and detection on the temperature of the sidewall lining concrete showed that a qualification rate of >91% was satisfactorily obtained by using the proposed approach.

Simulation of Smoke Movement in a Loop Corridor under Mechanical Exhaust with Compound Model

2013 ◽  
Vol 475-476 ◽  
pp. 1459-1462
Author(s):  
Wei Shi ◽  
Fu Sheng Gao
Keyword(s):  
Field Model ◽  
Unit Area ◽  
Zone Model ◽  
Smoke Control ◽  
Smoke Movement ◽  
High Rise ◽  
Compound Model ◽  
Ceiling Height ◽  
Dynamic Simulator ◽  
Fire Dynamic Simulator

The mechanical smoke exhaust is as acknowledged as an effective smoke control manner by making use of some necessary exhaust facilities, also with more stability than natural exhaust. In this paper, the field model FDS (Fire Dynamic Simulator) with a combination of zone model CFAST (Consolidate Fire and Smoke Transport) were used to simulate the mechanical smoke exhaust in a loop corridor of the fire floor in a high-rise hotel, for the propose of evaluate fire safety of mechanical smoke exhaust. The mainly discussion was about the height of layer interface with the ceiling height changed, also with different smoke exhaust volume. The conclusions were obtained that, when two exhaust vents were set symmetrically in the loop corridor, the volume of smoke exhaust per unit area with 60m3/h according to regulations, always could ensure safety of smoke exhaust. The smoke exhausted worse within the corridor when ceiling height reduced. It was recommended that the ceiling lowest height limit should be provides in correlative regulation.

Smoke Control System for High-Rise Buildings in Japan

2011 ◽  
Vol 6 (6) ◽  
pp. 551-557 ◽  
Author(s):  
Shuji Moriyama ◽  
Keyword(s):  
Control System ◽  
Basic Concept ◽  
Exhaust System ◽  
Smoke Control ◽  
High Rise ◽  
Air Tightness ◽  
Opening And Closing ◽  
Smoke Control System ◽  
Combustible Materials

A smoke exhaust system must be installed basically in all high-rise buildings in Japan, in order to eliminate smoke and gas from combustible materials and ensure safe evacuation effectively. However, a new problem, i.e., the difficulty of opening and closing doors when a smoke exhaust fan is operating, has occurred since air-tightness has been improved in high-rise buildings. There are therefore many cases recently where a pressurized smoke control system is adopted. In this paper, the basic concept of this system is described and the pressurized smoke control system that is used in Harumi Triton Square, one of the largest high-rise buildings in Japan.

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