Title: Characterisation of a thermal plume evolving in a confined environment: application to fire in tunnel

Authors: Hatem Saafi; Ahmedou Ould Mohamed Mahmoud; Rejeb Ben Maad

Addresses: Laboratory of Energy and Thermal and Mass Transfers, Department of Physics, Faculty of Sciences of Tunis, University of Tunis El Manar, 2092 El Manar, Tunis, Tunisia ' Department of Physics, Faculty of Sciences and Techniques of Nouakchott, Unité de nouvelle Technologies d'Energie et Systèmes Thermo Fluides, BP 5026, Nouakchott, Mauritania ' Laboratory of Energy and Thermal and Mass Transfers, Department of Physics, Faculty of Sciences of Tunis, University of Tunis El Manar, 2092 El Manar, Tunis, Tunisia

Abstract: This investigation analyses the behaviour of a turbulent thermal plume evolving in a horizontal tunnel. The thermal plume is created by a hot disk. First, we studied the evolution of the thermal plume without ventilation system. The study of the average and fluctuating thermal and dynamic fields shows three zones during the vertical evolution of the free plume. A first zone close to the source, serving to the plume supply in fresh air, is characterised by the apparition of three exhausts of the thermal plume. Followed by a second zone where the main escape undergoes a contraction. Finally, a third zone where the thermal plume accumulates and undergoes a flow upstream named backlayering and a flow downstream that borders the ceiling to leave by the free part of the tunnel. We then determined the effects of the source site and longitudinal ventilation on the plume structure.

Keywords: fire plume; tunnel fires; thermal plume; turbulent convection; natural convection; confined environments; source site; longitudinal ventilation; plume structure.

DOI: 10.1504/IJESMS.2015.070111

International Journal of Engineering Systems Modelling and Simulation, 2015 Vol.7 No.3, pp.202 - 212

Received: 04 Jan 2014
Accepted: 22 Apr 2014
Published online: 27 Jun 2015 *

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