Numerical Investigation of Two Simultaneous Fires in a Tunnel and Evaluation of the Obstructive Influence of Vehicles by Large Eddy Simulation

Mapar, Maryam; Heidarinejad, Ghassem; Pasdarshahri, Hadi

Numerical Investigation of Two Simultaneous Fires in a Tunnel and Evaluation of the Obstructive Influence of Vehicles by Large Eddy Simulation

Authors

Maryam Mapar

Ghassem Heidarinejad

Hadi Pasdarshahri

Tehran, Ale Ahmad Ave, Tarbiat Modares University, Department of Mechanical Engineering, Room 309

Abstract

In this paper a simulation of two fires in a tunnel in which varied arrangements of different sized vehicles at the upstream of fires has been accomplished using FDS. The results reveal that the behavior of two fires is directly influenced by distance between them. The calculated critical velocity is not affected by the variations on the small vehicles arrangement and distance between the vehicles and fires. Interestingly, the presence of medium vehicles leads ventilation flow to strengthen inertial force rather than buoyant force of fire plume in tunnel. Accordingly, when there is a short distance between fires and obstructions, less air ventilation is needed to prevent smoke backlayering. Eventually, far distance between the vehicles and the fires results in vanishing obstruction effects. Consequently, the critical velocity is the same as the case in which there is no vehicle in the tunnel.

Keywords

Tunnel

Fire

Large Eddy Simulation

Critical velocity