Study on the Smoke Exhaust Effect of Longitudinal Ventilation in Ultra-long Tunnels
Using FDS coupled Fluent numerical simulation method to study the fire process and the smoke exhaust process of the entire tunnel in the ultra-long river crossing cable tunnel.The smoke flow law during the smoke exhaust process of the entire tunnel was analyzed at a design cross-sectional wind speed of 2.2m/s.The results show that under the action of longitudinal ventilation airflow,the firewall only blocks the smoke 5 minutes before ventilation;In the entire tunnel smoke exhaust,the ventilation airflow continuously drives the smoke forward,while the smoke concentration is diluted.When exhausting smoke from tunnels of different lengths,there is a critical tunnel length.If the tunnel length is less than the critical length,achieving the safe concentration of smoke depends on pushing the smoke out of the tunnel;If the tunnel length is greater than the critical length,the smoke has already decreased to a safe concentration below the critical length,and there is no need to continue to exhaust smoke to the exhaust outlet.Based on this,the required smoke exhaust time for different tunnel lengths was obtained.
Ultra-long TunnelFDS coupling FluentVentilation and smoke exhaust after a fireEffective ventilation time
万方数据
维普
