Experimental Observations of the Low-Temperature Burning of Decane/Hexanol Droplets in Microgravity
Experimental Observations of the Low-Temperature Burning of Decane/Hexanol Droplets in Microgravity
复制标题
微重力下癸烷/己醇液滴低温燃烧的实验观察
DOI：
10.1080/00102202.2016.1225730
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发表时间：
2017
影响因子：
1.9
通讯作者：
Forman A. Williams
中科院分区：
文献类型：
--
作者：
D. Dietrich;R. Calabria;P. Massoli;V. Nayagam;Forman A. Williams
本文介绍了在国际空间站上进行的实验结果，该实验涉及在环境压力为0.05-0.30兆帕的空气中燃烧大的双组分正庚烷和正己醇(体积比为50/50)液滴。实验表明，在环境压力大于或等于0.10兆帕时，大液滴辐射熄灭后，存在持续的低温或冷焰燃烧。在常压下，正己醇/正庚烷液滴在冷焰熄灭时的液滴直径大于纯正庚烷液滴，表明正己醇抑制了冷焰燃烧。在0.20 Mpa下，纤维支撑的大液滴辐射熄灭，然后用冷火焰燃烧一段时间，然后热火焰自发重新点燃。在大约0.30兆帕的最高环境压力下，液滴再次辐射熄灭，并在凉爽的火焰中燃烧。然而，与0.20兆帕的测试相反，热火焰并没有自发重新点燃，而是用冷火焰燃烧到完成。此外，对所有相机和辐射计数据的更详细分析表明，在0.30兆帕下燃烧的冷火焰与在大气压下燃烧的冷火焰有根本的不同。这一结果似乎与基于目前可用的冷焰化学动力学的预期不一致，并可能表明需要不同的化学动力学机制。
ABSTRACT This article presents the results of experiments conducted aboard the International Space Station involving the combustion of large bi-component droplets of decane and hexanol (50/50 by volume) in air ambients with ambient pressures between 0.05 and 0.30 MPa. The experiments showed the presence of sustained low-temperature or cool-flame burning following radiative extinction of large droplets at ambient pressures greater than or equal to 0.10 MPa. The droplet diameters at cool-flame extinction were larger for the decane/hexanol droplets than for pure decane droplets at atmospheric pressure, suggesting that hexanol inhibits the cool-flame burning. At 0.20 MPa large fiber-supported droplets radiatively extinguished then burned with a cool flame for a period of time before the hot flame spontaneously re-ignited. At the highest ambient pressure of approximately 0.30 MPa the droplets again radiatively extinguished and burned with a cool flame. Contrary to the 0.20 MPa tests, however, the hot flame did not spontaneously re-ignite, but the droplet burned to completion with a cool flame. Further, more detailed analyses of all camera and radiometer data suggest that the cool-flame burning at 0.30 MPa is fundamentally different than the cool-flame burning at atmospheric pressure. This result does not appear to be consistent with expectations based on currently available cool-flame chemical kinetics and may suggest the need for a different chemical-kinetic mechanism.