How do liquid fuel physical properties affect liquid jet development in atomisers?
How do liquid fuel physical properties affect liquid jet development in atomisers?
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DOI：
10.1063/1.4965447
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发表时间：
2016-10-01
影响因子：
4.6
通讯作者：
Hardalupas, Yannis
中科院分区：
文献类型：
--
作者：
Charalampous, Georgios;Hardalupas, Yannis
液体燃料特性对雾化的影响仍然是一个悬而未决的问题。尽管液体性质发生微小变化，但使用不同燃料操作的雾化器产生的喷雾中的液滴尺寸可能会发生变化。本文通过实验研究了从普通孔口喷射的液体射流的发展，以评估由于液体特性的改变而导致的其行为变化，这可能会影响最终的雾化特性。考虑两种物理性质相似但不相同的航空煤油，即标准 JP8 煤油作为参考燃料，生物衍生加氢加工可再生喷气燃料作为替代生物燃料。相应的密度、动态粘度、运动粘度和表面张力分别变化约+5%、-5%、-10%和+5%，这是“直接”燃料替代的典型变化。通过实验考虑了液体射流行为的三个方面。通过喷嘴的液体射流的压力损失根据不同流量的流量系数进行检查。使用高放大倍数激光诱导荧光 (LIF) 成像可以可视化液体射流的形态。最后，通过对射流的双帧 LIF 成像测量进行时间相关运动分析，测量液体射流界面速度随距喷嘴出口距离的时间变化。结果表明，由于所考虑的液体燃料之间物理性质的微小变化，燃料的直接替代并没有导致燃料射流外部形态的剧烈变化。然而，物理性质的微小变化会改变液体的界面速度，从而改变内部射流速度分布。这些变化可以改变液体射流与周围环境的相互作用，包括同轴或交叉流雾化中的空气流，并影响液体燃料变化期间的雾化特性。 (C) 2016 年作者。
The influence of liquid fuel properties on atomisation remains an open question. The droplet sizes in sprays from atomisers operated with different fuels may be modified despite the small changes of the liquid properties. This paper examines experimentally the development of a liquid jet injected from a plain orifice in order to evaluate changes in its behaviour due to modifications of the liquid properties, which may influence the final atomisation characteristics. Two aviation kerosenes with similar, but not identical physical properties are considered, namely, standard JP8 kerosene as the reference fuel and bio-derived hydro-processed renewable jet fuel as an alternative biofuel. The corresponding density, dynamic viscosity, kinematic viscosity, and surface tension change by about +5%, -5%, -10%, and +5%, respectively, which are typical for "drop-in" fuel substitution. Three aspects of the liquid jet behaviour are experimentally considered. The pressure losses of the liquid jet through the nozzle are examined in terms of the discharge coefficient for different flowrates. The morphology of the liquid jet is visualised using high magnification Laser Induced Fluorescence (LIF) imaging. Finally, the temporal development of the liquid jet interfacial velocity as a function of distance from the nozzle exit is measured from time-dependent motion analysis of dual-frame LIF imaging measurements of the jet. The results show that for the small changes in the physical properties between the considered liquid fuels, the direct substitution of fuel did not result in a drastic change of the external morphology of the fuel jets. However, the small changes in the physical properties modify the interfacial velocities of the liquid and consequently the internal jet velocity profile. These changes can modify the interaction of the liquid jet with the surroundings, including air flows in coaxial or cross flow atomisation, and influence the atomisation characteristics during the changes of liquid fuels. (C) 2016 Author(s).