Microgravity experiments of droplet-array combustion were conducted under high ambient temperature conditions. N-decane droplet arrays suspended on SiC fibers were inserted into a high-temperature combustion chamber and were ignited at one end to initiate the flame spread at high-temperature air. Flame-spread modes, burning behaviors after the flame spread and flame spread rate were examined at different ambient temperatures. Experimental results showed that the appearance of flame spread modes and the flame-spread rate were affected by the ambient temperature. The flame spread rate increased with the ambient temperature. These facts were discussed based on temperature effects on the droplet heating and the development of the flammable-mixture layer around the next droplet. Effects of the ambient temperature on the appearance of group combustion of the array after the flame spread were also discussed.
Atomization of a round liquid jet is initiated by the excitation of Taylor instability immediately downstream of the nozzle exit. A self-sustaining mechanism of this process is theoretically explored on the basis of observation of the instability behaviors of a SF6 liquid issued into an otherwise stationary nitrogen gas at pressures exceed the critical pressure of SF6, which has the thermodynamic surface state close to the critical mixing condition. In micro-gravity condition, the vanishing surface tension allows us to use a liquid jet which is issued from a nozzle in laminar flow form at a low speed in order to realize an equivalent condition to a high speed jet at low pressures. The mechanism for the disintegration of the liquid jet at short wavelength, which is characteristic to the near-critical mixing surface jet, is also proposed on the basis of the experimental observation and theoretical consideration.