Enhancement of smoke extraction in tunnels in the case of fire by using L-shape curtain near smoke extraction vents

Abstract

One of the challenges in the case of fire in tunnels is how to limit the propagation of smoke efficiently. Solid curtains which are released from the tunnel ceiling at the time of fire can prevent the smoke from further spread in the tunnel. The main issue with the traditional straight shape curtains is that there is no guarantee for providing a complete safe environment as enough visibility, temperature, and smoke concentration for the people at the region where the smoke is trapped behind the curtain. This paper introduces an idea to make a modification of the straight curtain shape to be L-shape and to use it at a location close to the smoke extraction vent. Results showed that in the case of straight curtain, part of the smoke moves downward after hitting the curtain and then diffuses at low elevations. On the other hand, the L-shape curtain redirects the smoke stream moving downward about 90° before being captured by the smoke extraction vent. The L-shape curtain increased the visibility and provided lower temperatures and smoke concentration compared with the straight curtain shape. Moreover, L-shape curtain created better interaction with the vent resulting in higher smoke flow extraction rate.