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title炭素やホウ素といった高エネルギ密度燃料粒子の燃焼完結に不可欠な条件に関して
Other TitleCritical Conditions for the Particle Burn-out of High-Energy-Density Fuels, Such as Carbon and/or Boron
Author(jpn)牧野, 敦
Author(eng)Makino, Atsushi
Author Affiliation(jpn)宇宙航空研究開発機構研究開発本部ジェットエンジン技術研究センター(JAXA)
Author Affiliation(eng)Jet Engine Technology Research Center, Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency (JAXA)
Issue Date2013-02-28
Publisher宇宙航空研究開発機構(JAXA)
Japan Aerospace Exploration Agency (JAXA)
Publication title宇宙航空研究開発機構研究開発報告
JAXA reseach and development report
VolumeJAXA-RR-12-003
Start page1
End page25
Publication date2013-02-28
Languagejpn
eng
Abstract高エネルギ密度燃料と呼ばれる高い発熱量を有する固体の元素は,推進薬の高性能化に寄与しうる燃料として注目されている.ここでは,高エネルギ密度燃料が加熱された後,燃焼へと移行しうる条件について,数値的・解析的に調べている.検討対象として取り上げた固体は固体炭素で,石炭燃焼の基礎研究でも用いられてきたがゆえに,他の物質に比べて燃焼特性が格段によく把握されており,ここではこれを高エネルギ密度燃料のモデル燃料として用いいる.その結果,初期粒径,雰囲気温度,圧力,酸素濃度などがある値以下となると,燃焼時間が急増することが数値計算により見出された.また,初期加熱が終了し温度が準定常状態に到達した粒子に対して,可燃性気体の自己着火と同様の解析手法(漸近解析法)を適用することにより,表面反応が活性化されうる条件や粒径の下限界が解析的に導出された.さらに,初期粒径,酸素濃度,雰囲気圧力から構成される包括パラメタも導出され,しかも,これが雰囲気温度のみの関数となっていることが判明した.その上,本解析結果は,文献中の実験結果と傾向ならびに概略値が一致しており,本解析が現象の本質を捉えていることが明らかになった.また,ホウ素粒子の燃焼に関しても,粒子表面に形成される酸化被膜が高温で除去された後の燃焼状況では,炭素粒子の燃焼と全く同様な取扱いが可能で,限界粒径ならびに包括パラメタが同様に求められたし,解析結果と文献中の実験結果とは傾向ならびに概略値の一致が確認された.
Solid elements with high volumetric and/or gravimetric heating values, so-called the high-energy-density fuels, have attracted special interests as fuels that can contribute much for enhancing performance of propellants. In the present study, endeavor has been made, not only numerically but also analytically, to elucidate the critical condition that the high-energy-density fuels can move to the combustion after the initial heating. Material chosen for this aim, as a representative fuel, is the solid carbon whose combustion characteristics have well been understood, by virtue of basic researches for the coal combustion, compared to the others. It is found from numerical calculations that there appear abrupt increases in the particle burn-out time when the dominant parameters, such as the initial particle size, oxygen concentration, ambient temperature, and pressure, are below the critical values, respectively. In addition, by conducting asymptotics for the particle in the quasi-steady state established after the initial heating, in the same manner as that for the spontaneous ignition of gaseous combustibles, conducted in the 1930s, it has succeeded in analytically deriving the lower bound of particle size to be burned completely, as well as the critical condition for the surface reaction to be activated. A comprehensive parameter, consisting of the initial particle size, oxygen concentration, and ambient pressure, has also been obtained, which only depends on the ambient temperature. A fair degree of agreement has further been demonstrated between the present analytical results and experimental data in the literature, as far as the trend and the approximate magnitude are concerned, suggesting that the present analysis has captured the essential feature of the phenomena considered. As for the combustion of boron particles, after removal of oxide films on the particle surfaces at high temperatures, by conducting the same analysis as that for the carbon particle, not only the lower bound of the particle size, but also the comprehensive parameter can be derived, with presenting fair agreement between the analytical and experimental results.
Document TypeTechnical Report
JAXA Category研究開発報告
ISSN1349-1113
NCIDAA1192675X
SHI-NOAA0061885000
Report NoJAXA-RR-12-003
URIhttps://repository.exst.jaxa.jp/dspace/handle/a-is/19883


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