1993 Fiscal Year Final Research Report Summary
Ignition and Combustion of MG and Al as Fuel of a Jet Engine in Mars Atmosphere at Low Pressures
| Project/Area Number |
03452100
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Aerospace engineering
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| Research Institution | Tokyo Metropolitan Institute of Technology |
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Principal Investigator |
YUASA Saburo Tokyo Metro.Inst.Tech., Aerospace Eng., Professor, 工学部, 教授 (60123147)
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| Co-Investigator(Kenkyū-buntansha) |
GOTO Noboru Tokyo Metro.Inst.Tech., Aerospace Eng., Assistant, 工学部, 助手 (50099363)
ISODA Hiroshi Otsuma Women's Univ., School of Social Inform.Studies, Professor, 社会情報学部, 教授 (80012186)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Planet Atmosphere / Jet Engine / Carbon Dioxide / Low Pressure / Ignition / Combustion / Magnesium / Aluminum |
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| Research Abstract |
The prospects for using Al and Mg as fuel in a jet engine in Mars atmosphere without oxygen lead to this experimental study on the ignition and combustion of Al and Mg performed in pure CO_2 streams over a wide range of ambient pressure and velocity of the streams. Both Al and Mg could ignite spontaneously and burn in the CO_2 streams at low pressures.
For Al the critical ignition temperature decreased with decreasing pressure and velocity of the streams. Whether surface reactions proceeded initially to form a protective Al_2O_3 film on the Al surface or not playd a crucial role in the ignition process. No oxide film led to ignition. This is controlled by inward diffusion of CO_2 to the surface. During combustion, AlO, CO and condensed Al_2O_3 were produced in the flame due to the reaction of Al vapor with CO_2, and the Al surface, generating Al_2O, remained clean.
For Mg, the critical ignition temperature in CO_2 streams decreased with decreasing pressure, and was insensitive to the stream velocity. Ignition occurred in two distinct stages, first being surface reactions controlled by chemical kinetics and second being gas-phase reactions controlled by CO_2 diffusion. The breaking of a thin protective film formed in the first stage playd a crucial role in the ignition process, leading to the beginning of the gas-phase reactions and the to ignition. During combustion, several flames appeared sporadically and intermittently over the swelling sample surface which was coated with a thick porous layr. The flames produced CO in the gas phase, while on the non-flame surface the reactions of Mg with both CO diffusing from the flames and CO_2 in the streams generated condensed MgO and C that built the porous layr.
The burning rates of Al in the CO_2 streams were estimated to be much lower than those of Mg in a CO_2 stream. A burning method of Mg in the combustor of the engine is proposed.
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