Effect of Ambient Temperature on Flame Spread of an N-decane Droplet Array under Microgravity

Paper number

IAC-05-A2.7.04

Author

Dr. Masao Kikuchi, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Mr. Shin Yamamoto, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Prof. Shinichi Yoda, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan

Coauthor

Dr. Yuichiro Wakashima, National Institute of Advanced Industrial Science and Technology, Japan

Coauthor

Prof. Masato Mikami, Yamaguchi University, Japan

Year

2005

Abstract

Flame spread of a fuel droplet array has been studied as fundamental investigations of spray combustion. However, most of the experiments were conducted at normal temperature environment. It is important to understand the effect of ambient temperature on flame spread of fuel droplets, since spray combustion may be occurred at high temperature environment in real combustors. 

In this study, flame spread phenomena of fuel droplet array were investigated at normal and elevated ambient temperatures with wide range of droplet spacing under microgravity environment. N-decane (C10H22) was employed as fuel. Each droplet was suspended on intersection of fine SiC fibers at normal temperature. Droplet array was inserted into a combustion chamber, which is equipped with electrical heater to achieve air with desired temperature. A droplet at one end of array was ignited by hot wire, and subsequent flame spread behaviors were observed. Time dependent behaviors of OH radical were also observed employing a high-speed video camera and an image intensifier. 4.5s drop shaft of Microgravity Laboratory of Japan (MGLAB) was utilized for microgravity experiments. 

In this paper, effects of ambient temperature on flame spread are discussed in detail based on experimental results at 450K and 750K which are newly obtained, as well as results at 300K and 600K which are already reported by Mikami et al. Characteristic flame spread modes, including propagation of premixed flame, were observed depending on ambient temperature and droplet spacing. Flame spread rates increased with ambient temperature. Especially, significant increases of flame spread rates were observed at 750K. Numerical simulations were also conducted to elucidate the experimental results. It was shown how ambient temperature affects flame spread process of fuel droplets.

Abstract document

IAC-05-A2.7.04.pdf

Manuscript document

IAC-05-A2.7.04.pdf (🔒 authorized access only).

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