Enclosure finely-dispersed water fire fighting features

Abstract

Enclosure fire fighting by finely-dispersed water capability without direct water droplet flow effect from a sprayer upon a fire is shown. Fire fighting requirement droplet flow investigation experience points at successful application of Zauter’s diameter (volume of all droplets to their surface relation) while describing the results of experimental studies and theoretical calculations. With presence of enclosure eddy medium motion on account of ascending combustion product flow and interaction with a sprayer droplet flow in a finely-dispersed droplet ensemble there appear eddy diffusion, migration, deposition, and Magnus effect phenomena. With turbulent gas flow mode the particle deposition velocity on pipe and channel walls in most cases surpasses Brownian deposition velocity of the same particles in eddy-free motion. The above phenomena are typical of fine droplets up to 150 μm in Zauter’s diameter. Droplets of 200 μm and larger diameter are not subjected to eddy gas motion effect, just depositing under force of gravity and initial impulse. A particle motion in gaseous medium follows its pulsations with this or that phase or amplitude lagging, i. e. asymmetrically, but with certain velocity excess to the side of lower magnitudes of pulsating medium velocity. Fine water droplet motion study in eddying gaseous medium allows to reveal processes facilitating fire suppression in the whole enclosure without direct water droplet flow effect from a sprayer upon a fire. The experimental studies performed on enclosure Class A and B fire suppression have demonstrated enclosure fire suppression capacity by finely-dispersed water with droplets of up to 50 μm in diameter that was predicted under theoretical consideration of fine droplets motion in eddying gas medium.