ABSTRACT
Ventilation system in tunnels is of a great importance in providing a safe condition for the people passing through the tunnel in both normal and emergency situations. This is usually performed by injecting fresh air into the tunnel and removing hazardous gases. In this research, the longitudinal ventilation of a 5-kilometer tunnel constructed in the Tehran-North freeway project, Iran, through straight jetfans is investigated. The effects of full congested traffic on the airflow rate imposed by the jetfans in this one-directional tunnel, and therefore, the function of ventilation system in removing the exhaust gases are studied. A 3D realistic computational domain for the tunnel with about 1100 stationary vehicles is developed and CFD simulations are performed. The results showed the traffic arrangement and the location of large vehicles in the tunnel has a significant impact on the performance of the ventilation system. The CFD data also suggested that the designed system is likely to fail in removing heat generated by the stationary vehicles in the tunnel and providing a safe condition for the passengers.
