Combustion and Evaporation of Liquid Fuel under the Supercritical Condition at Normal Gravity and Micro Gravity

1.常压下的高压燃烧实验（1）对于重油等多组分燃料，燃烧时间随环境压力的增加而迅速增加，当压力大于2 MPa时，燃烧时间几乎不变。这种趋势与单组分燃料的趋势相似。碳烟浓度随着环境压力的增加而迅速增加，并且在高于0.5MPa的压力下变得几乎恒定。(2)对于乳化燃料，在大气压下观察到微爆的发生，而在高于0.5MPa的压力下未观察到微爆。研究还发现，碳烟浓度随环境压力的增加而增加，然后趋于恒定.微重力条件下单组分燃料燃烧实验微重力场是由一个组件从6 m高度落下产生的，它可以产生约1 s的有效微重力时间。直接拍摄的照片显示，在液滴周围形成了球形火焰。微重力下的燃烧速率常数略小于正常重力下的燃烧速率常数.微重力条件下乳化燃料燃烧实验（1）正十六烷/水乳化液的等待时间（点火到微爆开始的时间）比正十二烷/水乳化液的要短得多。这一结果表明，微爆炸的发生在很大程度上受测试燃料的沸点。(2)在正常重力条件下，微爆炸的发生比微重力条件下早。这一结果表明，微爆炸行为受到重力条件的影响。目前正在对微爆炸的机理进行更详细的研究。

1. High Pressure Combustion Experiments under Normal Gravity(1) The burning time increases rapidly as the ambient pressure increases, and it becomes almost constant at pressures above 2 MPa, for the multicomponent fuel such as the heavy oil. This tendency is similar to that for single component fuels. The soot concentration increases rapidly with increase in the ambient pressure, and it becomes almost constant at pressures above 0.5 MPa.(2) For the emulsified fuel, the occurrence of microexplosion is observed at the atmospheric pressure, and it is not observed at the pressures above 0.5 MPa. It is also found that the soot concentration increases with increase in the ambient pressure and then it becomes almost constant.2. Combustion Experiments of the Single Component Fuel under Micro GravityThe Micro gravity field was generated by dropping an assembly from a height of 6 m, which can produce an effective time of micro gravity about 1 s. The direct photograph showed that the spherical flame was formed around the droplet. The burning rate constant at the micro gravity is slightly smaller than that at the normal gravity.3. Combustion Experiments of the Emulsified Fuel under Micro Gravity(1) The waiting time, which is defined as the time period between ignition and the onset of microexplosion, is much shorter for the n-hexadecane/water emulsion than that for the n-dodecane/water emulsion. This result suggests that the onset of microexplosion is largely affected by the boiling point of the test fuel.(2) The microexplosion begins to occur earlier under the normal gravity condition than the micro gravity condition. This result suggests that the microexplosion behavior is affected by the gravity condition. More detailed studies of the mechanism of the microexplosion are being carried out.