A study of wind effects on smoke extraction strategies in vehicle tunnels

The effects of winds on smoke spread in a vehicle tunnel have been studied. A 2.6 km vehicle tunnel in Taiwan was taken to be the case study with 50 MW ultra-fast fire scenarios. It has been found that wind can have adverse effects on smoke control. The results show that winds from the tunnel ends would cause high temperature smoke spreading through the tunnel. This study explored the strategies of using tunnel ventilation jet fans and point smoke extraction in combination to counter the wind effects. It has been found that proper control strategies could restrain smoke spread in the tunnel for a period of time. Different control strategies are presented separately for fire occurs at the tunnel center and at the tunnel entrance. The results were evaluated in terms of temperature, visibility and CO concentration, specifically at 2 m height from the floor level. The results show that smoke can be contained to a span of about 100 m for more than 300 s, and for as long as 900 s in more favorable cases. The results show that tenable conditions can be maintained a period of time to prolong the evacuation time.