Evolution of a liquid-drop aerosol cloud in the atmosphere

This paper focuses on the physical-mathematical model of liquid-drop aerosol cloud evolution. It describes the results of experimental research on how the droplets lose the stability of their shape in streams of two types: at moderate (10 ≤ Re ≤ 100) and low (Re < 1) Reynolds numbers in a range of high Bond numbers. The paper describes the empirical dependence of droplet deformation on the Weber number. It is discovered that the critical value of the Bond number corresponding to the beginning of droplet deformation depends on the flow mode (Reynolds number). New experimental data is presented for the loss of the droplet’s shape stability in a range of low Reynolds numbers by the Rayleigh-Taylor mechanism. An approximating formula is derived for coagulation and crash of colliding droplets in a diphasic stream. A mathematical model of liquid-drop aerosol cloud evolution is presented, including equations of droplet movement and convective heat exchange of a droplet with the atmosphere and an equation describing the change of droplet size due to evaporation. Results of mathematical modeling are represented for dynamics of toxic aerosols during the fall of exhausted stages of carrier rockets in cases of depressurization of fuel tanks for different sizes of fuel droplets and the altitude of the emission, considering the real weather conditions. Using the presented model, an analysis of the negative impact of emergency aviation fuel discharge is conducted. Calculation results are presented for the altitude of emergency aviation fuel discharge needed for the complete evaporation of kerosene droplets.