Multi-scale powder dispersal solution using the General Dynamic Equation
Amir Shalel  1@  , David Katoshevski  2, *@  , Tali Bar-Kohany  3, *@  
1 : Safety and Management Engineering Unit, Ben-Gurion University of the Negev
2 : Ben Gurion University
Beer Sheva -  Israel
3 : Tel-Aviv University& nrcn
School of Mechanical Engineering -  Israel
* : Corresponding author

In this study, we have extended the aerosol general dynamic equation (GDE), to deal with multi-scale and multivariable
problems. As a case study, we examine the dynamics of an extinguishing aerosol or a powder in a reacting
flow. The purpose of this application is to find ways to minimize the amount of extinguishing aerosol/powder that is
required, using a multi variable approach.
The aim of the first phase of the study, which is presented here, is to develop a theoretical approach to simulate
the dynamics of aerosol particles in a flow field utilizing the GDE. The extended GDE in the case study represents
distributions of particle mass, particle temperature and particle velocity. The case study for demonstration
is the interaction of the aerosol particles with premixed laminar Ozone burning, which has a relatively simple reaction
model. We disperse powder at the flame zone upstream and find the powder concentration and initial size
distribution required to extinguish the flame.
The simulation considers two known extinguishing mechanisms:
1. Homogeneous mechanism, i.e.: a) Removal of heat from the flame reaction while powder particles are being
evaporated and b) Direct inhibition reaction of the powder evaporation products with the Fire Free Radicals.
2. Heterogeneous mechanism, i.e.: a) Mechanical interference of “powder cloud” with the FFR, acting as Flame
arrestor, and B) Chemical absorption of FFR onto particle surface while another FFR is expected to react with the
first one and recombine due to particle's surface energy dissipation. The product is desorbed from particle and does
not promote completion of oxidation

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