Subway Tunnels And Stations Within The Flow Characteristics Of The Numerical Simulation

With deterioration of the problems including traffic, environment contamination, energy crisis, etc all over the world, the development of Urban Rail Transit gains more and more recognition. Because of its advantage of safety, comfort, celerity, punctuality, high carrying capacity, low energy consume and low contamination, urban subway becomes increasingly favorite. With the rapid construction and development of the urban subway transport around the world, people pay more and more attention to the problems of the subway environment problems that include temperature, humidity, airflow velocity, pressure and air quality in subway environment.In this paper, flow characteristics both in subway tunnel and subway station when trains are in motion have been investigated by utilizing Computational Fluid Dynamics (CFD) numerical method and the commercial CFD software used for simulation is CFdesign8.0.The piston effect caused by train traveling in tunnel has significant influence on the air flow in tunnel. The characteristics of airflow caused by piston effect in one-directional tunnel were studied and the influence of factors such as train velocity, tunnel blockage and so on was obtained. In addition, the distributions of velocity and pressure in bi-directional tunnel were discussed primarily when trains are running towards each other.The airflow in subway station is complicated three-dimensional unsteady turbulent flow. A typical simplified three-dimensional geometry model of subway station was established in this paper, and transient simulations were carried out for five typical traffic conditions (which include one train pulls in, one train pulls out, one train pulls in meanwhile one train pulls out, two train pull in simultaneously and two train pull out simultaneously) in different operation mode of the station to present the detailed distributions of flow field in the station in each condition. On the basis of simulation results, the effects of circulating trains on the environment in the station and their role in natural ventilation of the station were indicated.Air temperature is one of the most important factors of the subway environment control. The thermal environment in subway system was analyzed and the heat released from kinds of inner heat source was evaluated respectively. By solving differential equation of heat balance, a function between temperature in the station and the time is...