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

• Published in: Journal of engineering physics and thermophysics 2023, Vol.96 (1), p.130-142
• Main Authors: Voitkov, I. S., Zhdanova, A. O., Kropotova, S. S., Kuznetsov, G. V., Tkachenko, P. P.
• Format: Article
• Language: English
• Subjects: Aerosols; Classical Mechanics; Clouds; Coagulation; Collisions; Complex Systems; Droplets; Engineering; Engineering Thermodynamics; Extinguishing; Heat and Mass Transfer; Industrial Chemistry/Chemical Engineering; Interaction parameters; Surface tension; Thermodynamics; Weber number
• ISSN: 1062-0125; 1573-871X
• DOI: 10.1007/s10891-023-02669-1

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·s and a viscosity of 0.07269–0.08241 N/m, in an aerosol cloud with a droplet concentration γ 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°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.