Fire behaviour and external flames in corridor and tunnel-like enclosures T. Beji, S. Ukleja, J. Zhang* ,† and M. A. Delichatsios 1 FireSERT, School of Built Environment and Built Environment Research Institute, University of Ulster, Newtownabbey, BT38 8GQ, Northern Ireland, UK ABSTRACT This work investigates how the inflow, the burning and the outflow develop in a corridor open to one end having a fire at either the closed or open end. The situation of a corridor fire having a fire source at the close end is a situation similar to a tunnel having a fire source at the centre of the tunnel without ventilation. A gaseous propane burner is used to produce the fire at a prescribed fuel flow rate in a long corridor of aspect ratio up to 6:1 having a rectangular cross section and varying door-like openings. Gas temperatures using thermocouple trees, heat fluxes in the corridor and on its façade, flame heights of emerging flames and total heat release rates (HRRs) are measured as the fuel flow rate of propane increases gradually and linearly with time to a preset maximum value. For over-ventilated conditions, the flames remain near the fire source at the closed end of the corridor. Unexpectedly, it is established for under-ventilated conditions that the inflow of air is not affected by the aspect ratio of the corridor or the location of the burner in the corridor and that the vertical distribution of gas temperatures inside the enclosure is nearly uniform with height everywhere. In addition, the flame heights and heat fluxes on the façade are the same as those for aspect ratios of the corridor from 1:1 to 3:1 examined in previous work. Moreover, as the conditions changed from over-ventilated to under-ventilated conditions, the flames migrated in a ghostly manner from the closed end to the open end of the corridor as soon as under-ventilated conditions were established. The speed of migration of the flames from the back to the front has also been inferred from the thermocouple tree measurements, which also in- dicate that the flow conditions ahead and after the passing of the front are changed. These results can be ap- plied to interpret some of the observed behaviours of fires in long corridors or tunnels without ventilation. Copyright © 2012 John Wiley & Sons, Ltd. Received 28 November 2010; Revised 11 June 2011; Accepted 22 September 2011 KEY WORDS: enclosure fires; façade fires; corridor; tunnel like enclosures 1. INTRODUCTION Flame heights and heat fluxes in facade flames originating from enclosure fires are needed for the design of separation distances to prevent flame spread from floor to floor and to adjacent buildings. Over the last decades, much effort has been devoted to studying flame heights and heat fluxes in external façades from a burning enclosure [1–8], which has led to better understanding of the physics of the flows and to the development of new relations for the emerging flames on inert facades in ventilation-controlled (under-ventilated) fires at the floor of fire origin [6,7]. By systematically performing in this work a series of small-scale experiments having various enclosure geometries, fire locations and door-like openings, the physics of the flows and new relations are underpinned for the emerging flames on inert facades in ventilation-controlled (under- ventilated) fires at the floor of fire origin. To avoid the interactive variation of the HRR, propane gas *Correspondence to: J. Zhang, FireSERT, School of Built Environment and Built Environment Research Institute, Uni- versity of Ulster, Newtownabbey, BT38 8GQ, Northern Ireland, UK. † E-mail: j.zhang@ulster.ac.uk Copyright © 2012 John Wiley & Sons, Ltd. FIRE AND MATERIALS Fire Mater. (2012) Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/fam.1124