Abstract: Computational Fluid Dynamics (CFD) simulations have been employed to study tunnel fires by both academics and engineers. Whether the simulation results are reasonable depends significantly on whether or not, a reasonable fire scenario can be simulated. For example, can the effect of a traffic jam upstream of a fire, which blocks the air flow due through the ventilation system, on the heat release rate of the burning vehicle and movement of smoke in a real tunnel fire scenario be reasonably neglected? This research utilizes reduced scale experiments and CFD analysis to investigate the effect of issues, including the size of blocked vehicle upstream of a fire and distance between the blocked vehicle and the burning vehicle, on the tunnel environment during a fire.

Key words: numerical simulation, backlayering of smoke, heat release rate, ventilation air flow