Experiments on Droplets in Free Fall I: Terminal Velocity and Wall Effects

Abstract

A system is described for accurately generating droplets of known size in the diameter range 300–500 μ, and measuring their terminal velocity in air. The error in terminal velocity is <0.5%. Measurements were made using several diameters of tubing to investigate the effect of walls on the terminal velocity of droplets. These data are compared with those of other authors. The wall effect on drag coefficient falls to the 1% level at approximately 70 droplet diameters.