Experimental study on evaporation characteristics of fire-extinguishing agent droplets in a thermal convection environment

Abstract Forest fires are highly destructive, and aerial firefighting aircraft are widely recognized as the safest and most efficient means of fire suppression. Under the combined influence of high-altitude wind fields and ground fire conditions, fire extinguishing agents sprayed at high-velocity experience rapid expansion, fragmentation, atomization, and evaporation, all of which can affect the effectiveness of fire suppression. To examine the evaporation loss characteristics of fire extinguishing agents, a test apparatus that simulates thermal convection conditions is developed, with the capability of conducting experiments using both the suspended and dropped methods. High-speed cameras were employed to record the complete evaporation process of the fire-extinguishing agent droplets in both methods, with image recognition techniques used to track changes in droplet diameter. Experimental results indicate that the dropped method results in a faster descent of the fire-extinguishing agent droplets, with minimal changes in droplet diameter over short periods. In contrast, the suspension method enables direct observation of droplet diameter changes, providing valuable insights into the evaporation characteristics of the fire-extinguishing agent droplets.