TheWind Velocity of Longitudinal Air Supply for the Central Smoke Extraction System on Tunnel Fire

  • JIANG Xuepeng;LIU Qi
  • 1. School of Faculty of Geosciences and Environmental Engineering, Southwest Jiao Tong University, Chengdu 610031, China;2. School of Civil Engineering, Central South University, Changsha 410075, China;3. Social Sciences School of, Hunan University of Chinese Medicine, Changsha 410208, China

Received date: 2013-01-04

  Revised date: 2013-01-23

  Online published: 2013-03-18


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 the visibility distribution at 2m height of the tunnel. Fire Dynamics Simulation (FDS) is employed to run numerical simulations based on a cross-river sloping tunnel. Twelve groups of fires conditions with -2.8% slopes are simulated. Different opening scheme on smoke extraction vents related to the fire location is taken into account. The smoke extraction vents opening schemes includes three upstream vents/three downstream vents, two upstream vents/four downstream vents, one upstream vent/five downstream vents with the mode of one-way central smoke extraction. And different velocities of longitudinal fresh air supply have been considered as well, which are 0 m/s, 1 m/s, 2 m/s, and 3m/s, respectively. The results of the simulation indicate that the reasonable velocity of longitudinal fresh air supply with central smoke extraction mode is 2.0m/s, which is smaller than the critical wind velocity with the same fire condition. Thus, the conclusion is able to help the smoke extraction system to operate effectively and safely.

Cite this article

JIANG Xuepeng;LIU Qi . TheWind Velocity of Longitudinal Air Supply for the Central Smoke Extraction System on Tunnel Fire[J]. Science & Technology Review, 2013 , 31(8) : 51 -56 . DOI: 10.3981/j.issn.1000-7857.2013.08.007