Abstract:

In order to reveal the effect of a tunnel with Fire Dynamics Simulator （FDS） is used to simulate a ceiling flues on personnel evacuation in fire, the software of medium-scale fire with a heat release rate of 20 MW. The smoke pervasion and temperature distribution varying with the flue-outlet exhaust velocity and the flue setting are then analyzed in detail. The results show that  the setting of ceiling flues improves the smoke density in the tunnel from 40mg/m³ to 120 mg/m³ inside the flue outlet and to 100 mg/m³ outside the outlet;  the exhaust at smoke outlets accelerates the moving of smoke from the tunnel into the flue, and greatly reduces the smoke density and temperature outside the two flue outlets near the fire source, thus increasing the safety coefficient for personnel evacuation ;  at an exhaust velocity of 2.5 m/s, the volume fraction of CO outside the flue outlet approximates to a constant less than 13 ×10^-6 after 300s, which offers a relatively safe space for personnel evacuation and fire rescue from both the upstream and the downstream; and  for the tunnel with ceiling flues, only two flues can be unlocked when a fire occurs.

Key words: fire, dynamic simulation, flue, smoke density, exhaust velocity, smoke pervasion