Influence of different transverse positions of two fires on flame characteristics in a tunnel

• Published in: Fire safety journal 2024-03, Vol.144, p.104104, Article 104104
• Main Authors: Xie, Qi, Peng, Wei, Liu, Xiaoyong, Liu, Xianhao, Zang, Xue, Ren, Junsheng, Zhang, Yan, Zhuo, Hui
• Format: Article
• Language: English
• Subjects: Air entrainment model; Fire source spacing; Lateral positions; Naturally ventilated tunnel; Two pool fires
• ISSN: 0379-7112
• DOI: 10.1016/j.firesaf.2024.104104

The flame-to-flame interaction in a dual-pool fire scenario is a crucial issue. However, current research on multiple fires in tunnels primarily focuses on scenarios where the fire sources are situated along the central axis of the tunnel. However, in real tunnel fires, the lateral positions of the fire sources are variable and unpredictable. Therefore, studying the flame behavior of two fire sources at different lateral positions within the tunnel is of significant importance in elucidating the interaction mechanisms between two fire sources inside the tunnel. In this investigation, a synergistic approach involving experimental inquiry and theoretical derivation was employed to systematically examine the phenomena of flame merging and tilting induced by two pool fires at diverse lateral positions within a naturally ventilated tunnel. The results indicate that flame entrainment is more likely to occur due to sidewall restrictions in tunnels, thereby increasing the probability of flame merging. A piecewise expression for determining the probability of flame merging from dual fire sources within tunnels was established. Furthermore, considering how sidewalls influence flame tilting angles, an air entrainment model for dual fire sources within tunnels was developed to derive flame tilting angles at different lateral positions and fire source spacing within tunnels. [Display omitted] •Studied flame traits of 2 heptane fires in a naturally ventilated tunnel.•Flame merging probability and tilt angle with different lateral fire positions. The maximum flame tilt angle is 24.20°.•Established dual-fire air entrainment model for predicting flame tilt angle.•Modified the velocity of flame entrains air from the region between fire sources.•Establishing the tilt angle of the flame by analyzing its geometric characteristics.