Optimization of Near-Source Concentrated Smoke Exhaust in Long Subway Station Entrance Passageways Under Concourse Fire Conditions

Smoke spread from concourse fires into long entrance passageways can threaten evacuation in deep-buried subway stations, especially when smoke moves upward along inclined escalator sections. This study used a 1:8-scale Fire Dynamics Simulator model to investigate smoke control in a concourse connected to two long entrance passageways. Concourse-only smoke exhaust, conventional combined smoke exhaust, different passageway vent configurations, and an optimized near-source concentrated arrangement were compared. The baseline concourse extraction rate failed to prevent smoke from entering the passageways. At a heat release rate of 15.55 kW, smoke was nearly prevented from entering landing I only when the concourse extraction rate was increased to six times the baseline value. Under conventional combined exhaust, the passageway extraction capacity was distributed between landing I and landing II, but smoke still entered escalator section I. When the total extraction rate of each single-side passageway was unchanged, concentrating the extraction capacity at landing I allowed smoke to be extracted before entering escalator section I. The optimized arrangement prevented smoke from entering escalator section I under both centered and right-offset fire source conditions for the tested passageway geometry, heat release rate, and extraction-rate conditions.