Experimental analysis of combustion intensity of irregular multiple pool fires based on the characteristics of flame merging, flame height, and mass loss rate

Multiple pool fires, a typical scenario of industrial thermal disasters, often occur in chemical fuel storage areas. To guide the industrial thermal safety management, the irregular multiple square pool fire experiments (side length d) with varying conditions of pool source pitches p (0-60 cm), pool numbers n (1-4), and layout patterns (linear-arranged, square-arranged) are conducted. The characteristic behaviors of the flame merging, the flame height, and the fuel mass loss rate are examined. The results include: an average flame merging probability P-m,P-a is proposed to quantify the merging intensity among irregular multiple pool fires, which exhibits a linear relationship with the ratio of pool source pitch to the multi-flame height at zero pitch p/H-p=0. Then, a predictive model is developed for the flame height, correlating it with the group parameter p(2)+nd(2)n / (p(2)+d(2)). A dimensionless average mass loss rate m(t)(& lowast;) is introduced to characterize the impact of interaction intensity on the global combustion of multiple fires. Due to the competitive effects of two dominant mechanisms, m(t)(& lowast; )initially increases and then decreases as the fuel surface area ratio r increases. Furthermore, under the dominant mechanism of radiative heat feedback and air entrainment, two change processes are observed in m(t)(& lowast;): a slow increase followed by a rapid rise. Within the experimental ranges, in non-zero pool source pitch scenarios, m(t)(& lowast;) is greater in the square-arranged configuration compared to m(t)(& lowast;) in the linear layout. The comprehensive impact coefficient A(i) is then employed to explore the influence of interaction strength on the individual fire sources. Overall, A(i) of the central fire exceeds that of the side fire. Additionally, the nondimensional parameter alpha is defined to reveal the extent of the impact of pool source pitch, pool number, and layout pattern on A(i). The influence of pool number and layout pattern on A(i) is relatively minor, with pool source pitch being dominant. Finally, based on the energy conservation principle, the heat transfer equation, and the solid flame model, a correlation for the mass loss rate of any pool in multiple fire sources is established. The above correlations are validated using the results of previous research, demonstrating their applicability and reliability.