THE BEHAVIOR OF LARGE LOW SURFACE TENSION WATER DROPS FALLING AT TERMINAL VELOCITY IN AIR

摘要

To study the behavior of large low surface tension drops in free fall a vertical wind tunnel was constructed. The tunnel is simple, but provides a low turbulence (0.7%) flow which stably supports large water drops falling at terminal velocity. The influence of reduced surface tension on maximum drop size, drop terminal velocity and drop shape was investigated. It was found that drops of low surface tension break up at a smaller size than normal surface tension drops, are more deformed than drops of equal mass but normal surface tension and have a lower terminal velocity than drops of equal mass and normal surface tension. Drops only partially coated with surfactant can not be stably supported and undergo violent oscillations.