On-site experimental analysis of the impact of subway trains passing on the ventilation performance of exhaust system

• Air velocities are tested on proposed systems in a typical subway station. • The effectiveness of two proposed systems is analyzed with/without train passage. • Air velocities at escalators exhibit a three-stage of decrease-increase-decrease. • The opening position of SSOs doesn't affect air velocities at escalators. Fire incidents pose a significant threat to the operational safety of subway platforms. Currently, research on smoke exhaust during subway platform fires primarily relies on numerical simulations or reduced-scale experiments, with limited availability of tested data of airflow organization. This study focuses on a typical station of Wuhan Metro Line 8, conducting air velocity tests at locations including platform escalator entrances, side smoke outlets of track-top air duct, and outlets of platform-hall smoke exhaust system under conditions of train overtaking (Train passes through the platform without stopping). This study captures the variations in air velocity at escalator entrances and side smoke exhaust outlets during different time periods of trains passage. Using the measured data, the study analyzes the operational effectiveness of the proposed two coordinated platform smoke exhaust modes. The results indicate that, in the absence of train movement, air velocities at various escalator entrances of YZH (Station called YZH) station consistently meet the standard requirements of >1.5 m/s throughout the entire testing period. During train overtaking, air velocities at measuring points of escalator entrances exhibit a three-stage trend of initial decrease, followed by an increase, and subsequent decrease. The time variation of air velocities at the escalator entrance is closely related to the total time of train movement. Additionally, the opening position of the side smoke exhaust openings on the track-top air duct doesn't have an obvious impact on the air velocity at escalator entrances. It is worth noting that while the tests did not involve a fire scenario, in the event of a fire, the ventilation capacity would likely be affected, and air velocity may decrease. However, the airflow characteristics and trends observed in this study provide valuable reference data for evaluating the system's performance under real-world conditions. This study, by providing experimental data, will support the operational effectiveness of smoke exhaust systems in real-world subway stations.