Experimental study on convergence of droplet streams under microgravity

Experiments on the convergence of two droplet streams have been carried out under microgravity in order to develop a technique for converging droplet streams under microgravity and to examine the behavior of droplets in a vacuum and under microgravity after the binary droplets collide with each other. The working fluid is silicone oil with a low vapor pressure. In this study, a method of orienting the droplet generators toward a convergence point has been tested. In all of the 68 experiments conducted under microgravity, it is confirmed that droplet streams are converged. It has been concluded that the method of orienting multiple droplet generators to a convergeing point is effective for converging droplet streams under microgravity. The behaviors of the colliding droplets under microgravity and in a vacuum have been classified into five types. The five types of behavior are mapped on a We (Weber number) — B (impact parameter) diagram. The range of Weber numbers in the experiments is from 200 to more than 3000.