STUDYING DROPLETS IN MICROGRAVITY

Microgravity represents a unique environment where experiments can be carried out to investigate unexplored branches of science. To this end, several spaceflight analogues are available to scientists to generate microgravity on Earth of different levels and durations. Aim of the paper is to report the first experimental results concerning the evaporation and combustion of droplets carried out at the ZARM micro gravity drop tower facility in Bremen. Droplets composed of fuel binary mixtures and water-in-oil emulsions have been studied in single droplet test cells specifically designed for microgravity conditions. The test cells are equipped with CMOS cameras and several sensors (bare thermocouples, pressure transducers, etc.) to control and manage the test progress inside the cell. The cells dedicated to droplets combustion studies are also equipped with UV, and IR sensors for the radiometric measurements. These measurements, coupled with CMOS camera video and the signals from the thermocouples, allow for a more comprehensive thermo-optical investigation of the processes exhibited by droplets. Miniaturization, robustness and lightness have been the main design constraints of the experimental system, being subject to accelerations/decelerations up to 50 g during the operation in the ZARM drop tower.