Numerical simulation of entrainment of water fragments from the zone of localization of combustion and pyrolysis of forest fuel materials by air flow

In the assessment of the scale of impact on the flame combustion, one of the most challenging factors is the influence of wind on the trajectory of fire extinguishing compositions in the gas medium during water discharge from aircraft. To predict the effect of surface transformation of free-falling volumes of water in the form of jets, drops and arrays, numerical modeling tools are essential. In this paper, the physical and mathematical models are developed, and empirical constants and dependences are calculated to take into account the size and shape of the drops in the reference points of the registration area. The results of our previous experiments and mathematical modeling both for the displacement of motion trajectories and for the coverage area of the model combustion center are found to fairly correspond. The ratios (characterizing the efficiency of typical systems of spraying and discharge) of water volumes entering the required zone of the model combustion center to total supply have been calculated. Using the developed model, the main characteristics of the studied entrainment of droplets, arrays and aerosols at the maximum possible air flow rates (up to 20 m/s) specific for hurricanes have been predicted. On the basis of the obtained approximations, the conditions of moderate and significant influence of a group of factors on the characteristics of liquid fragments entrainment have been predicted: The size and velocity, the air flow rate, the conditions of motion of an array, droplets or an aerosol cloud.