Microgravity experiments on flame spread along fuel-droplet arrays using a new droplet-generation technique

A new droplet-array generation technique achieved high quality and high reliability in microgravity experiments on multiple-droplet combustion. Each fuel droplet formed at the intersection of fine, X-shaped SiC fibers when liquid fuel was supplied through a fine glass tube. We aligned several sets of these X-shaped fibers and their corresponding fine glass tubes to form a droplet array. All the droplets in the array were simultaneously generated in a short time. In flame-spread experiments, a hot-wire igniter ignited an end droplet to initiate the flame spread along the array. We demonstrated microgravity experiments of droplet array combustion using the new droplet-array generation technique at a drop-experiment facility, MGLAB, in Japan. We successfully generated large droplets, which often fell off the fiber intersection in normal gravity, by using this method in microgravity. This technique is also effective in droplet-array combustion experiments using high-volatility fuel, where prevaporization is substantial. We compared the flame-spread rate and the flame-spread limit of these linear droplet arrays with results of an existing experiment, and discussed the effects of the suspending fiber on the flame spread.