Effect of fire intensity and burner size on thermal and flame merging characteristics of two parallel fire sources

Abstract: The merging of two parallel line fires is a common occurrence in forest fires. Studying the behavior of merging flames, along with the temperature and velocity of the surrounding flow fields in parallel line fires, improves our understanding of fire progression and transformation. This paper investigates how the flame merging process of two parallel rectangular fire sources affects centerline temperature, flame behavior, and velocity characteristics. The study employs computational simulation using Fire Dynamics Simulator (FDS), an open-source fire modeling tool that implements a multiphase approach, incorporating Large Eddy Simulation (LES) to simulate fluid turbulence. The numerical data have been validated through the application of the flame height approach derived from an experimental study. Various merging states of these line fires were explored by adjusting the heat release rates per unit area and the burner size. The findings from this study offer key insights into the interactions among parallel fire sources and their influence on thermal profiles and flaming behaviors. The results generally showed that as fire intensity increased for the same burner size, the flame heights rose accordingly. Moreover, when the burner size was increased, a notable increase in the centerline temperature and flame height was observed. Keywords: Thermal characteristic, Flame merging, Fire array, Fire intensity, Burner size