The critical atomization conditions of high-potential fire suppressant droplets in an air flow

Abstract

In this research, we used a high-speed video-recording system to experimentally study the surface transformation of droplets of water and water-based slurries, solutions, and emulsions exposed to the incoming air flow. The experimental parameters were varied in the following ranges: 0.3–3 mm for the initial droplet radius; 0.5–50 m/s for the air flow velocity; 10 vol% for the relative volume concentration of liquid additives to water; 10 wt% for the relative mass fraction of solid particles to water; 80–140 μm for the size of solid particles; 5–50 °C for the droplet temperature. Three regimes were identified: surface transformation without breakup; taking the bag shape followed by destruction; breakup into a cloud of small droplets. The novelty of the research lies in the maximum ratios of child droplet surface areas to the parent droplet surface area determined for the conditions typical of liquid discharge from various heights for fire suppression.