Fire extinction of forest fuels by droplets and water film

Paper presents the experimental results about fire extinction in the model  fire sites of forest combustible materials. We use the high-speed video recording tools during the experiments, as well as the system of multiphase media diagnostics based on panoramic optical flow visualization techniques. The presented experiments prove that it is possible to extinguish the forest combustible material (FCM) by small amount of water. The study considers several ways to stop FCM thermal decomposition: by individual large water droplets (1–3 mm), by an aerosol flow (the droplet size is from 0.05 mm to 0.12 mm), or through water film formation on the FCM surface. Typical durations of the FCM thermal decomposition and time of fire suppression  are determined for various conditions of interaction with water. The experimental results identify which amount of water is enough to extinguish the FCM by different ways of water transfer to the reacting surface layer. Furthermore, it is estimated how the component composition and the properties of the tested FCM mixtures effects onto the characteristics of the investigated processes. The residual fraction of the FCM was evaluated by comparison of initial and final (after extinguishing) mass of the sample.