Interactive combustion of two-dimensionally arranged quasi-droplet clusters under microgravity
Interactive combustion of two-dimensionally arranged quasi-droplet clusters under microgravity
复制标题
微重力下二维排列的准液滴簇的交互燃烧
DOI：
10.1016/s0010-2180(02)00353-x
复制
发表时间：
2002
影响因子：
4.4
通讯作者：
Y. Takeshita
中科院分区：
文献类型：
--
作者：
H. Nagata;I. Kudo;Kenichi Ito;Sosuke Nakamura;Y. Takeshita
为了研究喷雾燃烧过程中液滴间的相互作用，研究了微重力条件下二维排列的准液滴团簇的燃烧。准液滴样品由体积比为2：1的乙醇(丙醇、正丁醇、正戊醇或正己醇)和聚乙二醇组成，在室温下为固态，点火后立即转变为液体。电热镍铬丝同时点燃星团中的所有样品。星团周围出现了单一的包络火焰。结果表明，样品间距对火焰的形状和运动有很大影响。样品间距较大的样品团簇通过清扫燃烧模式进入外团燃烧，而小间距团簇则直接从外团燃烧开始。在较大的样本间隔时，从样本簇边缘到火焰的距离(火焰距离)增加到最大值，然后随时间减小。火焰的发展周期随着样品间距的减小而延长，最后，在足够小的样品间距下，火焰距离不断增加，直到火焰消失。这种火焰运动归因于燃料蒸汽累积效应，随着样品间距的减小，这种累积效应变得更加明显。随着样品间距的增加，燃烧寿命单调减小，并接近单一火焰的值。随着样品间距的增大，火焰距离单调减小，并逐渐接近单一火焰半径。这些结果对外部群聚燃烧现象有重要的印证，并证明了大液滴间距的扫气燃烧和小液滴间距的燃油蒸汽积累效应这两种不稳定特性在群聚燃烧中的重要性。
To investigate the mutual interactions between droplets in the spray combustion, combustion of 2-dimensionally arranged quasi-droplet clusters is studied under microgravity. Quasi-droplet samples, which are solid in room temperature and change into liquid just after the ignition, consist of alcohol (propanol, butanol, pentanol, or hexanol) and polyethylene glycol with a volumetric ratio of 2:1. Seven samples sustained by glass rods form a 2-dimensional quasi-droplet cluster. Electrically heated nichrome wires ignite all samples in the cluster simultaneously. Single envelope flames that surround the clusters appeared. The results show that the sample spacing has a strong effect on the shape and movement of the flame. Sample clusters with large sample spacings come to the external group combustion through the scavenging combustion mode, whereas the small spacing clusters start directly with the external group combustion. At large sample spacings, the distance from the edge of the sample cluster to the flame (flame distance) increases to a maximum value and then decreases with time. The period of flame growth is prolonged with decreasing sample spacing and finally, at a small enough sample spacing, the flame distance keeps increasing until the flame disappears. This flame movement is attributed to the fuel vapor accumulation effect, which becomes more dominant with decreasing sample spacing. The burning lifetime decreases monotonically and approaches the value of the single flame with increasing sample spacing. The flame distance decreases monotonically and approaches the single flame radius with increasing sample spacing also. These results render important confirmations of the external group combustion phenomena and prove the importance of the two kinds of unsteadiness, that is, the scavenging combustion with large droplet interval and the fuel vapor accumulation effect with small droplet interval, in group combustion.