Under the mode of central smoke extraction, in the case of a fire occurs inside the tunnel, jet fans at each end are able to operate and provide supply fresh air. The longitudinal fresh air supply is able to prevent smoke from spreading to the both sides of the tunnel, and control the smoke at the opening smoke extraction vents near the fire. Based on smoke control effectiveness, three evaluation indexes are proposed in order to judge the velocity of longitudinal fresh air supply, they are smoke-exhaust efficiency, smoke spread distance, and th...
