「きぼう」における液滴群燃焼実験「Group Combustion」

抄録

A Japan-U.S. joint research on liquid-fuel combustion experiment titled “Elucidation of Flame Spread and Group Combustion Excitation Mechanism of Randomly-distributed Droplet Clouds (Group Combustion)” is being prepared for the first combustion experiment in the Japanese Experimental Module “KIBO” on ISS. The objective of this experiment is to obtain flame-spread data to improve the percolation model to well describe the group combustion excitation through the flame spread. This research is expected to contribute to bridging the gap between the simplified droplet combustion in microgravity and complicated spray combustion. Percolation theory predicts that a transition occurs at the critical dropletnumber density between partial combustion and group combustion of fuel droplets in flame spreading over randomlydistributed droplet clouds. This transition is possibly identical to the transition between incomplete combustion and stabilized combustion in practical combustors. Application of percolation theory to flame spread of droplet clouds requires information on the flame spread between droplets. The present space experiments will investigate the effect of droplet interaction and free droplet on flame spread in a scale of droplet size order and effect of radiation heat loss, which becomes important in flame spread from a droplet cluster to another droplet cluster. This paper reports the background and current status of the preparation of the experiment.