Experimental and Numerical Simulation of Fire in a Scaled Underground Station

Authors: Nuri Yucel, Muhammed Ilter Berberoglu, Salih Karaaslan, Nureddin Dinler

Abstract:

The objective of this study is to investigate fire behaviors, experimentally and numerically, in a scaled version of an underground station. The effect of ventilation velocity on the fire is examined. Fire experiments are simulated by burning 10 ml isopropyl alcohol fuel in a fire pool with dimensions 5cm x 10cm x 4 mm at the center of 1/100 scaled underground station model. A commercial CFD program FLUENT was used in numerical simulations. For air flow simulations, k-ω SST turbulence model and for combustion simulation, non-premixed combustion model are used. This study showed that, the ventilation velocity is increased from 1 m/s to 3 m/s the maximum temperature in the station is found to be less for ventilation velocity of 1 m/s. The reason for these experimental result lies on the relative dominance of oxygen supply effect on cooling effect. Without piston effect, maximum temperature occurs above the fuel pool. However, when the ventilation velocity increased the flame was tilted in the direction of ventilation and the location of maximum temperature moves along the flow direction. The velocities measured experimentally in the station at different locations are well matched by the CFD simulation results. The prediction of general flow pattern is satisfactory with the smoke visualization tests. The backlayering in velocity is well predicted by CFD simulation. However, all over the station, the CFD simulations predicted higher temperatures compared to experimental measurements.

Keywords: Fire, underground station, flame propagation, CFDsimulation, k-ω SST turbulence model, non-premixed combustionmodel.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1332074

References:

[1] W.H. Park, D. H. Kim, H. C. Chang, "Numerical predictions of smoke movement in a subway station under ventilation," Safety in the Underground Space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and 32nd ITA General Assembly, 2006.
[2] Y. Wu, M. Z. A. Bakar, "Control of smoke flow in tunnel fires using longitudinal ventilation systems - a study of critical velocity," Fire Safety Journal, vol. 35, pp. 363-390, 2000.
[3] H. Xue, J. C. Ho, Y. M. Cheng, "Comparison of different combustion models in enclosure fire simulation," Fire Safety Journal, vol. 36, pp. 37-54, 2001.
[4] J. S. M. Li, W. K. Chow, "Numerical studies on performance evaluation of tunnel ventilation safety systems," Tunneling and Underground Space Technology, vol. 18, pp. 435-452, 2003.
[5] P. Z. Gao, S. L. Liu, W. K. Chow, N. K. Fong, "Large eddy simulations for studying tunnel smoke ventilation," Tunneling and Underground Space Technology, vol. 19, pp. 577-586, 2004.
[6] S. R. Lee, H. S. Ryou, "A numerical study on smoke movement in longitudinal ventilation tunnel fires for different aspect ratio," Building and Environment, vol. 41, pp. 719-725, 2006.
[7] C. J. Lin, Y. K. Chuah, "Smoke management design and computer simulation of an underground mass transit station in Taiwan," www.ncree.gov.tw/2004tcworkshop/pdf/14.pdf, 2004.
[8] H. Y. Wang, P. Joulain, "Numerical simulation of wind-aided flame propagation over horizontal surface of liquid fuel in a model tunnel," Journal of Loss Prevention in the Process Industries, vol. 20, issues 4-6, pp. 541-550, 2007.
[9] J. S. Roh, H. S. Ryou, D. H. Kim, W. S. Jung, Y. J. Jang, "Critical velocity and burning rate in pool fire during longitudinal ventilation," Tunneling and Underground Space Technology, vol. 22, pp. 262-271, 2007.
[10] C. C. Hwang, J. C. Edwards, "The critical ventilation velocity in tunnel fires - a computer simulation," Fire Safety Journal, vol. 40, pp. 213-244, 2005.
[11] P. H. Thomas, "The movement of smoke in horizontal passages against an air flow," Fire Research Station Note No.723, Fire Research Station UK, September, 1968.