Use of Mobile Fans in Tunnels

摘要

Several accidents have recently occurred, revealing how deadly fires in tunnels can be. Tragic events such as the one in the Mont Blanc tunnel or the St. Gotthard tunnel showed how hard it is for the first brigade to intervene with such fires. New equipment is now available to cope with fires in tunnels: namely, mobile fans placed at one end of the tunnel. By creating a jet-like air flow into the tunnel, which induces a fresh air flow with it, these fans can help to drive the heat and smoke in one direction, allowing fire fighters access to the fire. The air on the upstream side would become tolerable, giving fire fighters easier access to the fire source and improving their prospects of actually extinguishing the fire. The aim of the work described here was to investigate the limitations of this technique by using a Computational Fluid Dynamic (CFD) code. First, comparison was carried out with 'cold' experiments performed in two existing tunnels in Europe; the Manesse tunnel (0.5 km long) and the Kaferberg tunnel (2 km long). This was followed by a corresponding simulation of a 15 MW fire located in the middle of two trains at the centres of the Manesse tunnel and the Kaferberg tunnel. Buoyancy effects due to the slope of the tunnels were considered in the CFD simulation.