| Co-Investigator(Kenkyū-buntansha) |
NISHIYAMA Masaaki Tokyo Metro. Inst. Tech., Aerospace Eng., Assistant, 工学部, 助手 (30099353)
GOTO Noboru Tokyo Metro. Inst. Tech., Aerospace Eng., Assistant, 工学部, 助手 (50099363)
ISODA Hiroshi Tokyo Metro. Inst. Tech., Aerospace Eng., Professor, 工学部, 教授 (80012186)
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| Budget Amount *help |
¥5,300,000 (Direct Cost: ¥5,300,000)
Fiscal Year 1989: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1988: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Research Abstract |
A carbon dioxide breathing turbojet engine using metals as fuel has potential for an airplane engine which can work in Mars and Venus atmospheres, consisting of CO_2. Several possible metals for this purpose are Mg, Li, Al and B, because of their high heats of reaction with CO_2. In particular, Mg and Al which have higher flame temperatures, are more attractive fuels than Li and B. The feasibility of the engine was assessed by estimating the engine performance according to thermodynamic cycle analysis. The analysis indicates that although the engine consumes a large amount of metal fuel, it gives the sufficient value of thrust.
A fundamental study was performed experimentally on the ignition and combustion of the metals in an impinging pure C0_2 gas stream. It was found that Li, Mg and Al could ignite spontaneously in t-he stream. The spontaneous ignition temperatures of Li and Mg were much lower than that of Al. The ignition process of Li had two distinct steps, first a surface reaction and then a gas phase reaction. After,ignition, Li burned in vapor-phase at first and then on the metal surface. On the other hand, at the ignition in the stream, the Mg surface was covered with a protective film against further oxidation. When initial temperatures of Mg were higher than a Critical temperature, the film formed in early reaction stages became non-protective and then gas phase reactions occurred, leading to ignition. After ignition, Mg burned in vapor-phase throughout. The ignition process of Al was found to be similar to that of Mg. However, details of the process of Al have not been made clear so far. Among these four metals, only B could not ignite in the C0_2 stream, but the reactions occurred appreciably on the surface, and the molten boron oxide appeared on its surface.
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