Modeling of the dynamics of a liquid-droplet coolant under aerial firefighting

A mathematical model of the evolution of liquid-droplet aerosol cloud during the coolant discharge from a helibucket into the seat of fire is presented. The analysis of the main stages of coolant discharge is carried out. In the process of gravitational deposition of droplet cloud, the following aspects are taken into account: the droplet fragmentation by the Rayleigh–Taylor and Kelvin–Helmholtz mechanisms; the evaporation in a temperature field of a convective column; and the effect of the wind on the trajectories of droplets. The temperature and velocity distributions along the convective column above the seat of fire are simulated using the Yu.A. Gostintsev model. The velocity of the droplets is calculated in accordance with a trajectory approach. The calculation of the droplet evaporation is carried out in the framework of diffusion model and reduced film model. The computational results on the characteristics of the cloud of droplets penetrating into the seat of fire under typical conditions of aerial firefighting with the use of helibucket are presented.