The ranges of the aerodynamic drag coefficient of water droplets moving through typical gas media

Аннотация

The integral characteristics of the deformation processes of liquid (water) droplets moving through a gas medium (air at a temperature of about 300 K, kerosene combustion products with a temperature of about 1100 K) were experimentally investigated. The initial sizes (characteristic radii) of the droplets varied from 50 μm to 2.5 mm, and the initial velocities, from 0.5 m/s to 5 m/s. Velocities of the gas counter (relative to the direction of droplets displacement) flow weremaintained about 1.5 m/s by means of a special-purpose pressure system. Characteristic “deformation cycles” of droplets, their number, durations, and lengths, and also maximal amplitudes of the deformation process were identified. The ranges of numerical values of the aerodynamic drag coefficients c_d for the characteristic deformation cycles were determined. The influence of droplets velocities and sizes, and also of the gas medium temperature on these parameters was established. Characteristic times of preserving the corresponding droplet forms and c_d values within the range of the most typical deformation cycles were found.