Control strategy for emergency air flow in longitudinal ventilation tunnel with exhaust shaft

Abstract

Urban tunnels with exhaust shafts tend to increase lately when they are ventilated longitudinally. Since these tunnels need to be prepared for a fire incident in traffic congestions, the longitudinal airflow velocity at a fire must be controlled to zero promptly for passengers' safety. This ventilation system mainly consists of jet fans in the tunnel and exhaust fans in the shaft to control the longitudinal airflow. However, there have been few studies on how to operate the jet fans and exhaust fans systematically in order to achieve the best total safety. We propose a procedure based on simulations under different conditions by focusing on the airflow control at an emergency in the area between the shaft and the exit portal.