This research conducted microgravity experiments to investigate the flame-spread characteristics of the fueldroplet-cloud element with uneven droplet spacing, which is a basic element of a randomly distributed droplet cloud at the critical condition for group-combustion occurrence. Flame spread to a droplet followed by burning with two-droplet interaction was observed in microgravity to investigate the effect of flame-spread direction and local interactive effect. The results show that the flame-spread rate to a droplet in a perpendicular direction to the axis of two interacting droplets was greater than that to the droplet in the same direction as the axis of two interacting droplets. The temperature distribution around burning droplets was measured by the Thin Filament Pyrometry (TFP) method based on radiation from 14-micron SiC fibers suspending droplets at their intersections. The flame-spread-limit distance increased with two-droplet interaction in both flame-spread directions. This also shows the dependence of the flame-spread direction. The flame spreading after two-droplet interaction in different directions is discussed considering the temperature distribution development. An approximation of the flame-spread-limit distance is also presented.

During Marine Science Summer Course 2017, a continuous 24-h conductivity-temperature-depth (CTD) “yoyo” measurement has been carried out at the entrance of Padangbai Lombok Strait to investigate seawater properties variations on semidiurnal tidal-scale which is dominant in the strait. The SBE CTD 19 plus is equipped with optional sensors such as pH, turbidity and chlorophyll-a derived-fluoro. During 24-h field observation, 15 CTD casts from sea surface to about 60 m depth have been acquired. It is shown that observed seawater properties fluctuate strongly four times a day, following semidiurnal-tide period with two flood-tide and two ebb-tide conditions. During flood-tide, water mass is derived from open strait with colder, saltier, denser and low dissolved oxygen characteristics. In contrast, during ebb-tide, local water mass is recirculated back from the inner bay to the open strait. It is interesting to note that fluctuation of chlorophyll-a indicates a diurnal signal. In addition, fluctuation of pH, turbidity and dissolved oxygen showed a weak semidiurnal signal.