scholarly journals CFD model to assess parameters influencing piston wind in a subway tunnel and station

2021 ◽  
Vol 2042 (1) ◽  
pp. 012076
Author(s):  
Loreline Faugier ◽  
Benoît G. Marinus ◽  
Walter Bosschaerts ◽  
Delphine Laboureur ◽  
Karim Limam
Keyword(s):  
Subway Station ◽  
Cfd Model ◽  
Subway Tunnel ◽  
Air Velocity ◽  
Tunnel Length ◽  
Train Speed ◽  
Subway Stations ◽  
Dynamic Meshing ◽  
Double Track ◽  
Air Circulation

Abstract Quantifying the train-induced wind affecting the climate of subway stations can be applied to improve underground networks air quality. In this paper, numerical simulations of train-induced airflow in a subway station are performed, using a CFD model with dynamic meshing techniques. A preliminary study is done in a double-track tunnel with blockage ratios of 0.30, 0.37 and 0.46 with a train running at constant speed in the order of 10 m/s. The tunnel length necessary to obtain a stable flow around the train body is determined, and this upstream tunnel length is included in a subway station model. Two different architectures and three train speeds are simulated, and the effect of these configurations on the station airflow is evaluated through the air velocity and the mass flow rate at a location on the platform. The results evidence an increase in air circulation with blockage ratio and train speed.

Solutions for Extracting Air and Smoke in Underground Subway Station

2014 ◽  
Vol 700 ◽  
pp. 239-244
Author(s):  
Wen Jie Chen ◽  
Lei Chong ◽  
Jian Ru Liang ◽  
Ming Lai Yang
Keyword(s):  
Ventilation System ◽  
Subway Station ◽  
Three Solutions ◽  
Underground Subway Station ◽  
Subway System ◽  
Subway Stations ◽  
Underground Station ◽  
Enclosed Space ◽  
Air Circulation ◽  
Valve Control

Everyday there are about 7 million passengers commuting by subway in Shanghai, China. Although Shanghai has one of the largest subway networks in the world, yet this subway system is still full of passengers during the rush hours. Extracting air and smoke is important part of the station ventilation system which supplies enough fresh air in the crowded station. As we know, the underground subway stations are built in an enclosed space where needs air circulation far more than other type of station. This paper focuses on the designs of duct layout and valve control in an underground subway station. The authors give three solutions to return air and exhaust smoke in the underground station platform area and entrance area. The goal of this paper is to compare these three ventilation solutions in the normal time and in the fire accident. The result of analyzing and applying these solutions are concluded in the paper.

scholarly journals Characterization of Airborne Bacteria at an Underground Subway Station

2012 ◽  
Vol 78 (6) ◽  
pp. 1917-1929 ◽  
Author(s):  
Marius Dybwad ◽  
Per Einar Granum ◽  
Per Bruheim ◽  
Janet Martha Blatny
Keyword(s):  
Real Life ◽  
Performance Criteria ◽  
Anthropogenic Sources ◽  
Subway Station ◽  
Airborne Bacteria ◽  
Surveillance Systems ◽  
Operational Environment ◽  
Biological Detection ◽  
Content Type ◽  
Subway Stations

ABSTRACTThe reliable detection of airborne biological threat agents depends on several factors, including the performance criteria of the detector and its operational environment. One step in improving the detector's performance is to increase our knowledge of the biological aerosol background in potential operational environments. Subway stations are enclosed public environments, which may be regarded as potential targets for incidents involving biological threat agents. In this study, the airborne bacterial community at a subway station in Norway was characterized (concentration level, diversity, and virulence- and survival-associated properties). In addition, a SASS 3100 high-volume air sampler and a matrix-assisted laser desorption ionization–time of flight mass spectrometry-based isolate screening procedure was used for these studies. The daytime level of airborne bacteria at the station was higher than the nighttime and outdoor levels, and the relative bacterial spore number was higher in outdoor air than at the station. The bacterial content, particle concentration, and size distribution were stable within each environment throughout the study (May to September 2010). The majority of the airborne bacteria belonged to the generaBacillus,Micrococcus, andStaphylococcus, but a total of 37 different genera were identified in the air. These results suggest that anthropogenic sources are major contributors to airborne bacteria at subway stations and that such airborne communities could harbor virulence- and survival-associated properties of potential relevance for biological detection and surveillance, as well as for public health. Our findings also contribute to the development of realistic testing and evaluation schemes for biological detection/surveillance systems by providing information that can be used to mimic real-life operational airborne environments in controlled aerosol test chambers.

Influence of Ground Structure on the Seismic Response of Underground Subway Station in Soft Site

2011 ◽  
Vol 368-373 ◽  
pp. 2769-2775 ◽  
Author(s):  
Hui Long ◽  
Guo Xing Chen ◽  
Hai Yang Zhuang
Keyword(s):  
Seismic Response ◽  
Underground Structure ◽  
Outer Part ◽  
Subway Station ◽  
Analysis Model ◽  
Ground Structure ◽  
Element Analysis ◽  
High Rise ◽  
Underground Subway Station ◽  
Subway Stations

This paper selected representative soft site along the subway lines and created two-dimensional overall finite element analysis model about nonlinear dynamic interaction among soil, underground subway station, and ground structure based on Nanjing underground subway station. It explored the seismic response influence of neighboring high-rise structure on the two-layer and three-span island-type underground subway stations. The results showed that the structure near the subway station had a significant constraint effect on the deformation of subway station which is oriented to the structure, and the influence of deformation of subway station which is backward to the structure is related to vibration characteristics of the soil-underground structure interaction system. The influence of neighboring ground structure on the strain stress response of subway station is useful in most part of important nodes. However, this influence is disadvantageous in the outer part of connections of side walls and plates and middle plate-interior column connections.

Effect of Initial Velocity Field on Smoke Diffusion Characteristic in Subway Tunnel

2009 ◽  
Author(s):  
Hui Yang ◽  
Li Jia ◽  
Lixin Yang
Keyword(s):  
Velocity Field ◽  
Field Condition ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Wind Effect ◽  
Diffusion Characteristic ◽  
Subway Tunnel ◽  
Air Velocity ◽  
Initial Field ◽  
Fire Disaster

In this paper, piston wind effect on smoke diffusion characteristic in subway tunnel is studied by using three-dimensional transient computational fluid dynamics (CFD) method. In the first simulation case, fire disaster is simulated with homogeneous resting initial field condition. In the second simulation case, the train’s decelerating process till stopping in the tunnel is simulated for getting three-dimensional tunnel air velocity field distribution. Then the final heterogeneous air velocity field when the train stops in the tunnel is taken as initial field condition and the same fire scenario as the first case is simulated again. The data obtained under both initial conditions are compared by detecting people evacuation safety and the influence of initial air velocity field is analyzed. The results show that the inertial air velocity field caused by train’s movement has significant influence on smoke diffusion at the first few minutes of fire disaster, which is the key time for people’s evacuation. The adopted method in this paper and the simulation result could be used in establishing more effective subway fire evacuation plan.

Planning for shield driven double track subway tunnel of box shape

2020 ◽  
pp. 647-652
Author(s):  
H. Nakamura ◽  
M. Furukawa ◽  
N. Yamaguchi ◽  
S. Mizota
Keyword(s):  
Subway Tunnel ◽  
Double Track

scholarly journals Adaptability Analysis of Service Facilities in Transfer Subway Stations

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Liya Yao ◽  
Lishan Sun ◽  
Wuhong Wang ◽  
Hui Xiong
Keyword(s):  
Flow Characteristics ◽  
Transportation Systems ◽  
Subway Station ◽  
Security Level ◽  
Service Capability ◽  
Subway Stations ◽  
Pedestrian Transportation ◽  
Planning And Construction ◽  
Facility Size ◽  
Operation Status

Service capability and matching degree of transfer facilities are directly related to the operational efficiency and safety of a subway station. Owing to differences in planning and construction, the transfer subway stations in developing countries have some defects in facility size and serviceability, which cause a decline in service performance, operation efficiency, and security level. In order to solve the problems, traffic investigations were conducted on the form, size, and operation status of several typical transfer subway facilities. The service facilities were classified within a subway station in this research by considering service objects, service forms, service functions, and several other features. In addition, pedestrian behavior and pedestrian flow characteristics in different service facilities were analyzed in detail. The research results are deemed meaningful for the optimization of service facilities in subway stations and for the development of urban pedestrian transportation systems.

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.

Vehicle Parameters Influence on Railway Double-Track Pre-Stressed Concrete Continuous Bridge Vertical Load-Carrying Natural Frequency

2012 ◽  
Vol 446-449 ◽  
pp. 2544-2547
Author(s):  
Jiang Ying Ren ◽  
Mu Biao Su ◽  
Wen Ping Li
Keyword(s):  
Natural Frequency ◽  
High Speed ◽  
Vertical Load ◽  
Suspension Spring ◽  
Passenger Vehicles ◽  
Load Carrying ◽  
Train Speed ◽  
Girder Bridge ◽  
Double Track ◽  
Bridge System

When two lines with 20 same high-speed passenger vehicles are traveling on the 40 m+4×72 m+40 m party pre-stressed concrete continuous box-girder bridge from both ends, this bridge vertical load-carrying frequency is calculated with the vehicle-bridge system mode1. When the vehicle parameters, such as the unsprung mass of each wheel-set of the vehicle, the suspension spring stiffness, the vehicle length and the mass of the vehicle, are changed, the bridge vertical load-carrying frequencies are changed too. But when the train speed is changed, the bridge vertical load-carrying frequencies aren’t changed. It is shown that the bridge vertical load-carrying frequency is the vehicle-bridge system natural frequency, it is only depend on its natural parameters.

scholarly journals Optimization of guide vane positions in bended inflow of mechanical draft wet-cooling tower

2011 ◽  
Vol 32 (3) ◽  
pp. 263-272
Author(s):  
Adam Klimanek ◽  
Tomasz Musioł ◽  
Adam Stechman
Keyword(s):  
Standard Deviation ◽  
Velocity Distribution ◽  
Objective Function ◽  
Cooling Tower ◽  
Guide Vane ◽  
Optimization Procedure ◽  
Cfd Model ◽  
Air Velocity ◽  
Ansys Fluent ◽  
Flow Solver

Optimization of guide vane positions in bended inflow of mechanical draft wet-cooling tower Optimization of vane positions in a mechanical draft wet-cooling tower is presented in this paper. The originally installed, equally spaced, vanes produced non-uniform air velocity distribution reducing the performance of the fill of the cooling tower. A 2D CFD model of the tower has been created. The model has then been used to determine the objective function in the optimization procedure. The selected objective function was the standard deviation of the velocity of air entering the fill. The Goal Driven Optimization tools of the ANSYSWorkbench 2.0 have been used for the optimization and the ANSYS Fluent 13.0 as a flow solver. The optimization allowed reduction of the objective function and producing a more uniform air flow.

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