fire

Subway is consisted of tunnels, platforms and ventilation shafts. The air flow between these structures forms a ventilation network. There is a need for fire modeling tools capable of both rapid and precise simulation for fire and smoke propagation in such ventilation network. Computational Fluid Dynamics (CFD) is widely used in subway fire performance design. However, the boundary conditions used in models are always assumed to be constant.

Velocity fields on the platform area and flow rate of the smoke extraction system were experimentally measured under the different fan-operation modes in an actual subway station in Beijing. The velocity at the four tunnels connected with the station and velocity at the stairs between platform and concourses were obtained. Through simulation based on the measured results, the smoke velocity, temperature and concentration in case of station fire under the different fan-operation modes were analysed, and the optimal smoke extraction mode was proposed.

Fires in buildings account for 60% of fires in Taiwan. Since establishment of the National Fire Agency in  1995, many fire codes have been promulgated resulting in a gradual decline in the number of casualties of fire. However, for old apartments in urban areas, although regulations aimed at improving fire-prevention refuge facilities and fire-fighting equipment of existing building have been announced, they cannot be implemented efficiently due to the lack of public acceptance. This investigation has found that hundreds of thousands people live in such buildings.

Occupant evacuation dynamics is a kind of manybody system of strongly interacting persons. A great deal of factors should be taken into account in the study of fire evacuation, such as human behavior, fire products and architecture.

A model tunnel (approximately ten hydraulic diameters) with different designs of the tunnel mouth has been placed in a wind tunnel and has been subjected to the effects of external wind by varying the wind direction at the mouth of the tunnel. In the experimental oriented study pressures have been measured and the airflow has been made visible with smoke and by the sand erosion method (semolina). The relation between the flow ratio and the direction of the wind has been explored.

Full-scale burning tests were performed on wood, polymethylmethacrylate (PMMA), and methanol fires in a compartment with forced ventilation. The gas temperatures at seven positions were measured together with the transient mass loss rate of the fuel. Average temperatures of the hot gases were then compared with the values predicted by a simple model proposed by Deal and Bey/er (1990). The heat loss coefficient of the compartment was found to be an important parameter, and an empirical parameter is fitted from these tests with small fires.

Previous full scale experiments gave us a global and qualitative understanding of the gas circulation in a ventilated room in case of fire. In order to go thoroughly in the knowledge of these phenomena, we have built a scale model to perform more precise temperature measurements and more complete tracer gas experiments. The results show the existence of two zones when the air inlet is near the floor. At the opposite, when it is near the ceiling the room can be considered as a one single zone.