Evolution characteristics of fire smoke layer thickness in a mechanical ventilation tunnel with multiple point extraction

Author:  Mei, F. Z., Tang, F., Ling, X., Yu, J. S.

Journal: Applied Thermal Engineering

DOI:  10.1016/j.applthermaleng.2016.09.064

Keywords: Tunnel fires, Mechanical ventilation tunnel, Ceiling extraction, Smoke layer thickness, Plug-holing, longitudinal ventilation, ceiling extraction, natural ventilation, interface height, flow, tests, stratification, simulation, channel, profile

Abstract: 

A series of burning experiments were conducted in a model-scale mechanical ventilation tunnel to study the characteristics of smoke layer thickness and plug-holing with multiple point extraction system. Hot-wire anemometer and thermocouples trees were used to measure the flow velocity of ventilation outlet and vertical temperature profile in a mechanical ventilation tunnel, respectively. It was found that the smoke layer thickness was calculated by integral ratio method and within-class variance method were good agreement with visual observation value. The normalized temperature curves can be divided into two regions, such as, the plug-holing and without plug-holing. The smoke plug-holing exhaust rate and the d/H ratio of smoke layer depth to clear height decreased with increasing the number of point extraction opening for a given HRR. (C) 2016 Elsevier Ltd. All rights reserved.