Numerical study on ventilation duct layout in subway stations for smoke control performance optimization

Smoke is the most important threat to occupant safety in subway station fire accidents. However, only a few smoke control research has concerned the global ventilation system layout problem. With numerical simulation, this work explores the impact of ventilation system parameters on the smoke control efficiency in the hall area of a subway station. The proper ventilation duct layout distance is acquired according to the airflow field structure. The results suggest that: (1) The current ventilation system with two ducts 8m part in the subway station has been proved insufficient for smoke control with about 90% of the heat trapped in the station. (2) The lateral ventilation duct layout, i.e. the ventilation duct amount, is the decisive factor of the ventilation system efficiency. While ventilation volume and vent amount, which is generally considered important factors in traditional studies, show a limited impact on the overall ventilation efficiency. (3) A dimensionless airflow velocity is defined for ventilation duct influence range analysis. The influence range evaluation results are consistent with the tendency of smoke exhaust rate in different ventilation duct distance scenarios. The results could provide theoretical support for the ventilation duct layout design in subway stations.