Minimal Ventilation Velocity to Control Smoke in Subway Fire

Smoke-control of subway fire is always in a developing stage. In Airpak model of a subway platform, 30 MW fire is reconstructed, then along with 2 m3/(minldrm²) extraction level, 1.0~4.0 m/s longitudinal ventilation is activated to control its smoke back-layer. When ventilation velocity is not less than 2.0 m/s, temperature, mass rate of smoke and air quality stratify upstream fire source, and they level off after the velocity surpasses 2.5 m/s, which implies minimal ventilation velocity to control smoke back-layer exists and it comes out as 2.5 m/s in this case. Compared to critical ventilation velocity in many other studies, minimal ventilation velocity guarantees not only little burn, but also good visibility and low toxicity to evacuee and fire-fighter, a better index of smoke-control effectiveness in subway fire.