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Ignition and Combustion of MG and Al as Fuel of a Jet Engine in Mars Atmosphere at Low Pressures

MG 和 Al 作为喷气发动机燃料在火星大气低压下的点火和燃烧

基本信息

批准号：
03452100
负责人：
YUASA Saburo
金额：
$ 4.29万
依托单位：
Tokyo Metropolitan Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452100/
关键词：
Planet Atmosphere Jet Engine Carbon Dioxide Low Pressure Ignition Combustion Magnesium Aluminum

项目摘要

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.

由于铝和镁在火星无氧大气中作为喷气发动机燃料的前景，本实验研究了铝和镁在纯CO_2气流中在较宽的环境压力和气流速度范围内的着火和燃烧。铝和镁都能在低压下在CO_2气流中自燃，Al的临界着火温度随着气流压力和速度的降低而降低。表面反应是否在Al表面形成保护性的Al_2O_3膜对点火过程起着至关重要的作用。没有氧化膜导致点火。这是由CO_2向表面的向内扩散控制的。燃烧过程中，由于Al蒸气与CO2反应，火焰中生成AlO、CO和缩合的Al_2O_3，生成Al_2O的Al表面保持清洁；对于镁，CO_2气流的临界着火温度随压力的降低而降低，对气流速度的影响不大。着火分为两个不同的阶段，第一个阶段是由化学动力学控制的表面反应，第二个阶段是由CO2扩散控制的气相反应。第一阶段形成的薄层保护膜的破裂在点火过程中起着至关重要的作用，导致气相反应的开始和着火。在燃烧过程中，几个火焰零星和间歇性地出现在膨胀的样品表面，表面覆盖着厚厚的多孔层。火焰在气相中产生CO，而在无火焰表面上，镁与火焰中扩散的CO和蒸汽中的二氧化碳反应生成凝聚的氧化镁和碳，形成了多孔层。提出了镁在发动机燃烧室中的燃烧方法。