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Longitudinal air velocity control in a road tunnel during a fire event
Ventilation equipment is used during a fire event in a tunnel with bi-directional traffic and a transverse ventilation system to obtain two main aims: an air velocity lower than 1,5 m/s to make the smoke extraction near the fire position easier using open fire extraction dumpers and to limit diffusion of the combustion products along the tunnel to allow the fire brigades to operate. To obtain these aims, a great number of choices can be made by the ventilation manager. Furthermore, the impact of these choices on the air velocity and on smoke diffusion along the tunnel is influenced by the boundary conditions of the system: the outside temperature and pressure, including wind effects. The complex ventilation network of the Frejus tunnel is modelled in this paper using the graph theory. The possibilities of achieving the main aims has been investigated, studying more than 900 situations. Each situation has been defined taking into account the following parameters: the outside weather conditions, fire position, operating extraction fans, wind effects at the tunnel portals and the amount and position of the supplied fresh air. The obtained results show the air velocity and temperature distribution along the tunnel. The knowledge of the air velocity distribution allows one to verify whether the requirements concerning combustion product diffusion have been satisfied. Finally, the large number of obtained results has been analysed to outline general rules for the management of ventilation when a fire accident occurs.
Longitudinal air velocity control in a road tunnel during a fire event
Ventilation equipment is used during a fire event in a tunnel with bi-directional traffic and a transverse ventilation system to obtain two main aims: an air velocity lower than 1,5 m/s to make the smoke extraction near the fire position easier using open fire extraction dumpers and to limit diffusion of the combustion products along the tunnel to allow the fire brigades to operate. To obtain these aims, a great number of choices can be made by the ventilation manager. Furthermore, the impact of these choices on the air velocity and on smoke diffusion along the tunnel is influenced by the boundary conditions of the system: the outside temperature and pressure, including wind effects. The complex ventilation network of the Frejus tunnel is modelled in this paper using the graph theory. The possibilities of achieving the main aims has been investigated, studying more than 900 situations. Each situation has been defined taking into account the following parameters: the outside weather conditions, fire position, operating extraction fans, wind effects at the tunnel portals and the amount and position of the supplied fresh air. The obtained results show the air velocity and temperature distribution along the tunnel. The knowledge of the air velocity distribution allows one to verify whether the requirements concerning combustion product diffusion have been satisfied. Finally, the large number of obtained results has been analysed to outline general rules for the management of ventilation when a fire accident occurs.
Longitudinal air velocity control in a road tunnel during a fire event
Borchiellini, R. (author) / Ferro, V. (author) / Giaretto, V. (author)
2002
9 Seiten, 8 Bilder, 1 Tabelle, 8 Quellen
Conference paper
English
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