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Journal of Combustion
Volume 2017, Article ID 7125237, 12 pages
https://doi.org/10.1155/2017/7125237
Research Article

Numerical Investigation of Critical Velocity in Reduced Scale Tunnel Fire with Constant Heat Release Rate

1Laboratory of Combustion and Green Technologies, Department of Energy Engineering, University Institute of Technology, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon
2Department of Electrical Engineering, Energy and Automatics, National School of Agro-Industrial Sciences, University of Ngaoundere, Ngaoundere, Cameroon
3Department of Physics, University of Fada, Gourma Province, Burkina Faso
4Laboratory of Analysis, Simulation and Experiment (LASE), Department of Energy Engineering, University Institute of Technology, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon

Correspondence should be addressed to Ruben Mouangue; rf.oohay@eugnauom_r

Received 6 September 2016; Revised 23 November 2016; Accepted 12 December 2016; Published 18 January 2017

Academic Editor: Kaiyuan Li

Copyright © 2017 Ruben Mouangue et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

When a fire occurs in a tunnel in the absence of sufficient air supply, large quantities of smoke are generated, filling the vehicles and any space available around them. Hot gases and smoke produced by fire form layers flowing towards extremities of the tunnel which may interfere with person’s evacuation and firefighter’s intervention. This paper carries out a numerical simulation of an unexpected fire occurring in a one-way tunnel in order to investigate for the critical velocity of the ventilation airflow; this one is defined as the minimum velocity able to maintain the combustion products in the downstream side of tunnel. The computation is performed successively with two types of fuels representing a large and a small heat release rate, owing to an open source CFD code called ISIS, which is specific to fires in confined and nonconfined environments. It is indicated that, after several computations of full-scale fires of 43.103 and 19.103 kJ/kg as heat release rate, the velocities satisfying the criterion of healthy environment in the upstream side of the tunnel are 1.34 m/s and 1.12 m/s, respectively.