Recent Accomplishment of “Group Combustion” Experiments aboard Kibo on ISS

Abstract

The first microgravity combustion experiments were conducted in 2017 aboard the Japanese Experiment Module Kibo on ISS, titled Elucidation of Flame Spread and Group Combustion Excitation Mechanism of Randomly Distributed Droplet Clouds (Group Combustion). The objective of this experiment is to study the effects of droplet interaction, radiative heat loss from a flame, and droplet motion during flame spread. This report describes some recent accomplishments from the Group Combustion experiments with droplet-cloud elements to study the effects of droplet interaction and randomly distributed droplet clouds with about 100 droplets to study the macroscopic characteristics of flame spread and local flame spread characteristics. Two types of anomalous behavior observed near the group-combustion-excitation limit are also reported, which had not been expected from parabolic flight experiments and percolation calculations to express the group-combustion excitation through flame spread over droplets.