A study of optimal vent mode for the smoke control of subway station fire

摘要

Until now, the fire protection and emergency plan at the underground space has been made under the assumption that fire occurs only by accidents such as electro-mechanical fault as most fires have occurred accidentally. The subway station, a type of underground structure, is prone to the fire due to its structural characteristic of confined space where ventilation depends on the mechanical system and evacuation route is limited. Also, the strong buoyant characteristic of the hot smoke hinders fire brigades and safety guards to approach to the fire spot. The present study aims to evaluate the effectiveness of the smoke management system by fans, which can ensure the tenable environment for the evacuation of passengers in case of train fire. Visualization of soot propagated from fire source is realized using particle image velocimetry (PIV) with Ar-ion laser, which made possible to visually evaluate the soot movement characteristic and, hence, fire safety analysis. For the numerical simulation, a CFD modeling tool, fire dynamics simulator (FDS) Ver.4 developed in National Institute of Standards and Technology (NIST) is utilized in order to simulate the heat and smoke propagation phenomena in case of fire at platform in the subway station The basic principle of the PIV technique consists in the evaluation of the instantaneous fluid velocities by recording the position of images of small particles such as soots suspended in the fluid (here, gas) at successive instant.