Numerical study on the maximum temperature rise and thermal-smoke front spread length in the upstream of semi-transverse ventilated Underground Traffic Link Tunnels

To fill the gap between the high realistic demand and lack of research basis, the process of smoke spread in Underground Traffic Link Tunnel fires during operation is investigated by numerical modeling. Good agreement between numerical predictions and experimental measurements for the longitudinal temperature has been achieved. Good agreement between numerical predictions and experimental measurements for the longitudinal temperature has been achieved. The characteristics of smoke transportation at key locations (e.g., maximum excess temperature and smoke fronts) were analyzed. A novel division method for the maximum lengths of smoke bays, which depends on thermal-smoke front spread length established from the characteristic number Ri = Q̇fuel∗1/3/V∗ of mixed convection, to utilize the nature of smoke as much as possible during a fire is provided based on dimensional analysis and similarity principle. The margin of error between the final model prediction in this paper and the simulation was within plus or minus 10%. The outcomes of this study are believed to have practical guidance significance for linkage and interlock control of smoke management and passive fire protection design in tunnels during operation with a transverse ventilation system.