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Space-Based Microgravity Experiments on Flame Spread over Randomly Distributed n-Decane-Droplet Clouds: Overall Flame-Spread Characteristics

Published on Aug 1, 2018in Microgravity Science and Technology1.97
· DOI :10.1007/s12217-018-9637-2
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Yasuko Yoshida1
Estimated H-index: 1
(Yamaguchi University)
+ 4 AuthorsMasaki Nokura1
Estimated H-index: 1
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Abstract
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 paper is the first to report the group-combustion excitation of randomly distributed droplet clouds through flame spread and its dependence on the mean droplet spacing of the droplet cloud. The results show that there exists the group-combustion-excitation-limit mean droplet spacing. The flame-spread behavior is significantly affected by the initial conditions around the group-combustion-excitation limit, where the burning lifetime of the droplet cloud attains maximum and an interesting phenomenon, such as large-scale ignition, occurs. The group-combustion-excitation-limit mean droplet spacing is greater than the flame-spread-limit droplet spacing of the linear droplet array. The overall flame-spread rate of the droplet cloud is equivalent to or slightly greater than the flame-spread rate of the linear droplet array.
  • References (20)
  • Citations (1)
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References20
Newest
Published on Aug 1, 2018in Microgravity Science and Technology1.97
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Herman Saputro2
Estimated H-index: 2
(UNS: Sebelas Maret University)
+ 1 AuthorsHiroshi Oyagi3
Estimated H-index: 3
(Yamaguchi University)
Stable operation of liquid-fueled combustors requires the group combustion of fuel spray. Our study employs a percolation approach to describe unsteady group-combustion excitation based on findings obtained from microgravity experiments on the flame spread of fuel droplets. We focus on droplet clouds distributed randomly in three-dimensional square lattices with a low-volatility fuel, such as n-decane in room-temperature air, where the pre-vaporization effect is negligible. We also focus on the ...
Published on Jul 1, 2018in Combustion and Flame4.12
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Naoya Motomatsu1
Estimated H-index: 1
(Yamaguchi University)
+ 2 AuthorsTakehiko Seo4
Estimated H-index: 4
(Yamaguchi University)
Abstract This research investigates the flame-spread characteristics between two droplets, Droplets A and L, of different diameter. n -Decane droplets are placed at intersections of 14 µ SiC fibers. The flame spread from Droplet A to Droplet L was observed in microgravity. The results show that the flame-spread rate decreases with an increase in the droplet spacing or the initial diameter of Droplet L for a constant initial diameter of Droplet A. The flame-spread time is approximated as the summ...
Published on Jan 1, 2017in Journal of Thermal Science and Technology0.69
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Hidetaka Watari1
Estimated H-index: 1
(Yamaguchi University)
+ 4 AuthorsMasao Kikuchi7
Estimated H-index: 7
(JAXA: Japan Aerospace Exploration Agency)
Published on Jan 1, 2015
Yu Cheng Liu10
Estimated H-index: 10
(Cornell University),
Yuhao Xu7
Estimated H-index: 7
(Cornell University)
+ 1 AuthorsMichael C. Hicks8
Estimated H-index: 8
(Glenn Research Center)
Abstract This study reports experimental evidence of gas phase micro-convection induced by support fibers used in droplet combustion experimentation. Soot aggregates formed during combustion of n-octane and n-decane droplets (initial diameters ranging from 0.5 mm to 5 mm) provide natural seeds to reveal the thermal and flow asymmetries involved. The experiments are carried out in an environment that reduces the influence of forced and buoyant convection for both free-floating (unsupported) and f...
Published on Oct 1, 2014in Microgravity Science and Technology1.97
Daniel L. Dietrich13
Estimated H-index: 13
(Glenn Research Center),
Vedha Nayagam4
Estimated H-index: 4
(Case Western Reserve University)
+ 9 AuthorsYu Cheng Liu10
Estimated H-index: 10
(Cornell University)
This paper summarizes the first results from isolated droplet combustion experiments performed on the International Space Station (ISS). The long durations of microgravity provided in the ISS enable the measurement of droplet and flame histories over an unprecedented range of conditions. The first experiments were with heptane and methanol as fuels, initial droplet droplet diameters between 1.5 and 5.0 m m, ambient oxygen mole fractions between 0.1 and 0.4, ambient pressures between 0.7 and 3.0 ...
Published on Jan 1, 2013
Hiroshi Nomura9
Estimated H-index: 9
(College of Industrial Technology),
Hiromu Takahashi1
Estimated H-index: 1
(College of Industrial Technology)
+ 1 AuthorsMasao Kikuchi7
Estimated H-index: 7
(JAXA: Japan Aerospace Exploration Agency)
Abstract Combustion experiments of fuel droplet array in fuel-vapor/air mixture were performed at normal and microgravities to investigate mechanism of flame spread. A 10-droplet array was inserted into the test section filled with a saturated fuel-vapor/air mixture as a simple model of prevaporized sprays. Gas equivalence ratio of the fuel-vapor/air mixture was controlled by the test section temperature. n -Decane droplets of 0.8 mm in the initial diameter were employed. The first droplet was i...
Published on Apr 1, 2009in Combustion and Flame4.12
Hiroshi Oyagi3
Estimated H-index: 3
(Yamaguchi University),
Hisashi Shigeno1
Estimated H-index: 1
(Yamaguchi University)
+ 1 AuthorsNaoya Kojima10
Estimated H-index: 10
(Yamaguchi University)
We investigated the flame-spread characteristics of randomly arranged fuel-droplet arrays in microgravity. Flame-spread probability was calculated based on a percolation model with the flame-spread-limit distance of evenly-spaced n-decane droplet arrays in microgravity. Flame-spread probability depends on the occupation fraction of droplets in a lattice and rapidly increases with the occupation fraction. The local flame-spread-limit distance of unevenly-spaced n-decane droplet arrays was experim...
Published on Jan 1, 2009
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Yoshimi Mizuta1
Estimated H-index: 1
(Yamaguchi University)
+ 1 AuthorsNaoya Kojima10
Estimated H-index: 10
(Yamaguchi University)
Abstract An experimental study was performed on the combustion of lean-premixed spays in a counterflow. n -Decane was used as a liquid fuel with low volatility. The flame structure and stabilization were discussed based on the flame-spread mechanism of a droplet array with a low-volatility fuel. The spray flame consisted of a blue region and a yellow luminous region. The flame spread among droplets and group-flame formation through the droplet interaction were observed on the premixed spray side...
Published on Aug 1, 2006in Combustion and Flame4.12
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Hiroshi Oyagi3
Estimated H-index: 3
(Yamaguchi University)
+ 3 AuthorsShinichi Yoda21
Estimated H-index: 21
(JAXA: Japan Aerospace Exploration Agency)
Microgravity experiments on 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 in high-temperature air. Flame-spread modes, burning behavior after the flame spread, and flame-spread rate were examined at different ambient temperatures. Experimental results showed that the appearance of flame-spread modes ...
Cited By1
Newest
Yasuko Yoshida1
Estimated H-index: 1
(Yamaguchi University),
Takehiko Seo4
Estimated H-index: 4
(Yamaguchi University)
+ -3 AuthorsMasao Kikuchi7
Estimated H-index: 7
(JAXA: Japan Aerospace Exploration Agency)
Published on Jan 1, 2019
Yasuko Yoshida1
Estimated H-index: 1
(Yamaguchi University),
Kentaro Iwai (Yamaguchi University)+ 7 AuthorsMasaki Nokura1
Estimated H-index: 1
Abstract This research conducted microgravity experiments on the flame spread over droplet-cloud elements with strong droplet interaction aboard Kibo on the ISS. The droplet-cloud element represents a local droplet pattern appearing in randomly distributed droplet clouds near the group-combustion-excitation limit and consists of small-droplet-spacing droplets and large-droplet-spacing droplets. As droplet-cloud elements, we used four n -decane droplets, Droplets C, B, A and L, placed at fiber in...
Masao Kikuchi (JAXA: Japan Aerospace Exploration Agency), Yuji Kan (JAXA: Japan Aerospace Exploration Agency)
Masato Mikami14
Estimated H-index: 14
(Yamaguchi University),
Yasuko Yoshida1
Estimated H-index: 1
(Yamaguchi University)
+ -3 AuthorsYuji Kan (JAXA: Japan Aerospace Exploration Agency)