Tunable self-extinguishing of dripping fire mediated by impacted substrates

Dripping fire, caused by flammable liquids falling onto solid surfaces, presents a significant challenge for fire hazard management due to its concealed and unpredictable nature. In this study, we investigate the evaporation and burning characteristics of dripping fire and ascertain that self -extinguishment can occur under specific drip masses and frequencies owing to heat transfer from the heated substrate to the droplet and thermocapillary motion of burning droplets. By controlling these drip parameters, we observe three distinct burning regimes: non -extinguishing, self -extinguishing, and non -igniting; furthermore, we confirm that their critical drip masses and frequencies follow a power function with an exponent of 3/2. We develop an evaporation model to predict the occurrence of the self -extinguishing regime, which aligns well with experimental results. Additionally, by designing substrates with diverse surface structures and thermal properties to manipulate evaporation dynamics and motion behavior of burning droplets, it is possible to significantly reduce the burning duration of dripping fires from over 120 s to under 20 s. Overall, this finding offers a novel approach to mitigating fire hazards related to flammable drips in various settings such as buildings and industrial environments.