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

Published on May 1, 2005in Combustion and Flame4.12
· DOI :10.1016/j.combustflame.2005.01.007
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Hiroshi Oyagi4
Estimated H-index: 4
(Yamaguchi University)
+ 3 AuthorsShinichi Yoda22
Estimated H-index: 22
(JAXA: Japan Aerospace Exploration Agency)
Abstract
Abstract 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.
  • References (4)
  • Citations (37)
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#1I. Aharon (UC Davis: University of California, Davis)H-Index: 1
#2B.D. Shaw (UC Davis: University of California, Davis)H-Index: 2
Abstract Experiments on combustion of heptane/hexadecane mixture droplets were conducted in a reduced-gravity environment. Initial droplet diameters ranged from 0.47 to 1.5 mm, and initial hexadecane mass fractions ranged from 0.05 to 0.4. The ambient gas was O2/He (with O2 mole fractions of 0.3 and 0.5), or atmospheric air, and pressures were varied from 0.033 to 0.3 MPa (abs). A previous asymptotic theory was extended to allow data on flame contractions to be used to estimate liquid species di...
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#2Constantine M. Megaridis (UIC: University of Illinois at Chicago)H-Index: 38
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Burning behavior of a suspended fuel droplet under both normal and microgravity fields has been studied experimentally to explore the effects of natural convection at high ambient pressure levels up to four times the fuel critical pressure. The fuel employed was {ital n}-octane. Experiments have shown that the burning rate constant increases with the increase of the ambient pressure at subcritical pressures and decreases at supercritical pressures for both microgravity and normal gravity fields....
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This research conducted microgravity experiments on the flame spread over randomly distributed n-decane-droplet clouds aboard the Japanese Experiment Module “Kibo” on the International Space Station. 67-152 droplets were distributed at intersections of a 30 × 30 square lattice with 14-micron SiC fibers placed in a combustion chamber. One droplet on the bottom side of lattice was ignited by a hot-wire igniter to start the flame spread. The burning behavior was observed by a digital camera. This p...
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