Experimental study on interaction mechanism on the mass burning rate in two n-heptane fires with cross airflows

Abstract

This work aims to interpret the flame interaction mechanisms of the mass burning rates of two pool fires in a cross-airflow. The flame morphology, mass burning rate, and heat feedback components are measured. The results show that the mass burning rates of the two pool fires increase rapidly, then decrease, and finally increase slowly with wind speed. Owing to the blockage and air entrainment restriction effect of the upstream flame on cross airflow, the critical transition (from increasing to decaying) of the mass burning rate of the downstream flame corresponds to a relatively larger cross airflow speed under the same experimental conditions. In general, with increasing fire spacing, the dominant mechanism of flame interaction transitions from interactive blockage and air entrainment restriction to heat feedback enhancement to monopolar blockage and air entrainment restriction. The process of the primary control mechanism from radiation dominance to convection dominance with the increase of airflow speed is revealed. Finally, based on the stagnant layer theory, a model of the mass burning rates is developed for the convection-dominated multiple pool fires in the non-merging stage.