The Collision, Coalescence, and Disruption of Water Droplets

Using free pairs of droplets in the size range from 60 to 500 μ in radius, the effects of charge, velocity, and impact parameter on the collision and the disription of droplets have been examined. The impact parameters for collision and disruption of 300 and 60 μ radius droplets over a charge range from 10−15 to 10−12 C per droplet, and with impact velocity from 1 to 8 m/sec are reported. It is found that for droplets in this size and velocity range, electric charge on the droplets has no appreciable effect on the collision and coalescence process. However, the impact velocity and the impact parameter of the droplets dramatically affect the stability of the coalesced droplet. For 60 μ droplets, all collisions coalesce and form one droplet if the impact velocity is less than 2.2 m/sec. As the impact velocity is increased, the impact parameter for which only one droplet is produced after collision decreases and the all other collisions disrupt into several droplet fragments. For impact velocities greater than 8 m/sec, no collisions are stable.