Numerical simulation of ventilation modes in underground railway tunnel fire

In view of the fire occuring in the middle part of the train and the train stopping in the middle of the tunnel, proposes an improved longitudinal ventilation mode i.e. supplying air first from the lower side of the evacuation platform and then adopting conventional longitudinal ventilation mode, and numerically simulates its effect at this case. The results show that for the single track rectanglar cross-section tunnel and the fire intensity of 10 MW, air supply outlet group spacing 10 m and air volume of tunnel ventilation fan of 50 m³/s, or air supply outlet group spacing less than 30 m and air volume of 70 m³/s, can meet the requirements of fire safety for temperature, visibility and CO concentration limits. Also obtains that the critical wind velocity for longitudinal ventilation on both ends of underground railway tunnel is 2.4 to 2.8 m/s.