| Summary: | To control longitudinal smoke spread and increase the time available for evacuation at subway platforms, this paper proposes a system for separating smoke on subway platforms using a combination of external air supply platform air curtains, stair (or escalator) air curtains, and a mechanical smoke exhaust system. In this paper, CFD simulations are conducted using Fire Dynamics Simulator (FDS) to investigate the impact of various air curtain speeds at a 20° angle on smoke dispersion. The results show that: (1) The system is effective and reasonable, which can effectively prevent longitudinal smoke diffusion in the platform. (2) For the 2.5 MW firepower, when the air curtain speed is between 3 m/s and 5 m/s, the protected area is not affected by smoke. The supplementary cold air from the air curtains mixed and dispersed the heat, leading to a decrease in the temperature of the suspended ceiling above the fire source by approximately one-third, to below 200 °C. (3) For the 5.0 MW firepower, when the air curtain speed is 4 m/s, the protected area is not affected by smoke. The enhanced impact of the air curtain on fire source combustion surpasses the cooling effect of supplementary air.
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