Determination of the Distance Between the Droplets of Fire-Extinguishing Agents in an Aerosol Cloud at Which they do not Collide

Results of experimental investigations of the integral characteristics of the collisions of droplets of fire-extinguishing agents, having a surface tension of 0.0011-0.0014 Pa center dot s and a viscosity of 0.07269-0.08241 N/m, in an aerosol cloud with a droplet concentration gamma(d) = 0-7.142 L/m(3) are presented. The dependence of the number of collisions of such droplets in an aerosol cloud on their Weber number and linear interaction parameter was demonstrated. It was established that the frequency of realization of each of the regime of collisions of extinguishant droplets in an aerosol cloud (rebound, scattering, coagulation, and fragmentation) depends on the sizes of the droplets and their concentration in the cloud. The distances between the extinguishant droplets in an aerosol cloud, at which they do not collide, were determined with regard for the initial sizes of the droplets, the velocities of their movement, and the temperature to which they are heated (T = 20 and 600 degrees C). A general approximate expression has been constructed for estimating the distance between the droplets of different fire-extinguishing agents in an aerosol cloud, at which these droplets do not collide and, consequently, do not cause significant changes in the dispersivity of the cloud.

Automated summary

This study investigated the collision characteristics of fire-extinguishing agent droplets in an aerosol cloud. The results showed that the number of collisions depended on the droplets' Weber number and linear interaction parameter. The frequency of different collision modes depended on the droplets' size and concentration. The distances at which droplets did not collide were determined, and an approximate expression was constructed to estimate the distance between droplets of different fire-extinguishing agents in an aerosol cloud.