Experimental study on the flame performance and burning characteristics of two unequal rectangular pool fires

The production, transportation, and storage of combustible liquid fuel encounter substantial safety challenges, notably pool fires resulting from the seepage of storage vessels and pipelines. In practical fire incidents, multiple fire sources with varying pool dimensions and thermal loads are present, exacerbating the severity and uncontrollability of these disasters. Experiments were performed to explore the flame performance and burning characteristics from two unequal rectangular n-heptane fires with varied pool spacings (0–1 m) and area ratios of two rectangular pools (1–4 times). The results indicate a significant association between the three stages of flame interaction and the ratio of spacing to flame height at zero spacing (S/Lf,S=0). As S increased, the total mass burning rate increased at first and then decreased gradually owing to the competitive nature of heat feedback and air entrainment mechanisms, and the maximum value was reached when S equaled 1.5 times the pool width (S/w = 1.5). In the case of unequal double fire sources, it was observed that as the scale difference between the two fuel pools increased, the impact of interaction on the larger fuel pool became less pronounced. Conversely, the smaller-scale fuel pool experienced a more substantial heat feedback, resulting in a swift escalation in its mass burning rate. Combined with the stage of flame interaction, a piecewise model of flame height was proposed by incorporating the energy conservation principle and the air entrainment theory. The accuracy of the models concerning flame interaction intensity and flame height was validated through comparisons with data from existing literature. These models can also be extended for application to scenarios involving two identical fires and configurations with square arrays of fires.