Impact of ventilated tunnels on smoke peculiarities in train carriage fires with multiple lateral openings

Abstract

This research investigates the dynamics of smoke dispersion in a subway train carriage with multiple lateral openings within a ventilated subway tunnel. Numerous extensive full-scale numerical simulations were conducted to analyze the thermal plume distribution within multiple lateral openings of a train carriage, and the longitudinal and transverse maximum excess ceiling temperature. The results reveal that the heat release rates have a greater impact on the airflow in the carriage than velocities ,even when the longitudinal ventilation velocity reaches 8 m/s or the heat release rate reaches 15 MW. The multiple lateral openings cause significant differences in smoke flow characteristics compared to tunnels with both ends open. Additionally, the transverse maximum ceiling excess temperature inclines towards the lateral opening side due to asymmetrical air entrainment. The analysis of longitudinal maximum ceiling excess temperature identified two regions based on the dimensionless heat release rate, showing a linear increase followed by a constant phase dependent on the heat release rate, with a maximum longitudinal excess gas temperature of 1242 K. Additionally, a relationship between the dimensionless heat release rate and the transverse dimensionless maximum ceiling excess temperature was established. This study can be used as a guide for smoke exhaust mitigation and fire safety measures in the event of subway train carriage fires.