Study On Smoke Flow Simulation And Ventilation Control Of Double-deck Island Subway Station

Metro is one of the most promising public transport modes in the future. Due to the complexity and particularity of the underground structure, and large passenger flow, personnel concentration, when the fire occurs, the fire smoke spread to the upper along the stairs, and the main channel of personnel evacuation is the staircase. If harmful gas can not discharge timely, it will cause great obstacles to escape. Therefore,it is significant to study the characteristics of subway fire smoke flow and ventilation control for evacuation and escape.There are two kinds of research methods on the fire smoke flow and control,such as experiment and numerical simulation.building Experimental research model will take a long time, a large investment, and may not be able to get results. Relatively speaking,the numerical simulation study has the advantages of small investment,short cycle, easy control, and with the development of computer CFD software, the numerical simulation method has been widely used. In this paper, FLUENT software is used to simulate the subway fire smoke flow and ventilation control.In this paper, a double deck subway station with shield gate in Nanjing is taken as the research object, combining with the actual project closely, carried out the research on the flow characteristics of fire smoke in subway platform. According to the actual size of the platform, the mathematical model and physical model is established by using FLUENT software, respectively simulating the fire smoke flow in different size, different position of ignition and different velocity of air supply and exhaust. The station temperature field and concentration field of the smoke in different time periods of the station fire were studied. Finally, the simulation results were processed by Tecplot software, and the different fire conditions were compared and analyzed.By comparing the simulation result shows that the island subway station fire smoke control, whether fire occurs on the side or in the middle position, the smoke can not be timely discharged through the ventilation system under natural ventilation conditions. In the fire area, when the fire disaster size is the same, the smoke exhaust effect increased with the increase of the velocity of air supply and exhaust, and the maximum temperature and the smoke concentration of platform decreased with the increase of the velocity of air supply and exhaust;when the velocity of air supply and exhaust is the same, the smoke exhaust effect decreased with the increase of fire source size, and the maximum temperature and the smoke concentration of platform increased with the increase of fire source size. The results of this study not only provide direct theoretical basis and guidance for the design of ventilation system of the subway and provides reference to fire smoke flow control and safety evacuation of subway station fire, and is of important value for further research of subway fire and ventilation control.