Alternative jet fuels have a high potential to reduce emissions in aviation. A big difficulty for their introduction is the costly and lengthy assessment of fuel effects on combustion performance. In the present work, the evaporation of free-falling droplets of realistic size (D ≈ 80 μm) in a well-defined vertical laminar heated flow is studied experimentally and numerically. Measurements of droplet diameters and velocities using microscopic double-pulse shadowgraphy are conducted for several single species and systematically chosen conventional and alternative multicomponent jet fuels. The results show that the experiment is fuel-sensitive with respect to evaporation. In this study, special attention is paid to unknown or uncertain boundary and initial conditions, which serve as input in the validation of the numerical models. Therefore, nonintrusive, nondeterministic simulations using polynomial chaos expansion are performed to account for these uncertainties. The uncertainty quantification displays that overall uncertainties are small enough to distinguish between the different fuels and to predict fuel-dependent effects on evaporation. Nevertheless, the uncertainties are not negligible. A sensitivity analysis shows a high sensitivity of the evaporation to the offset of the droplet from the centerline and to the uncertainty of the inflow gas temperature. Reducing the uncertainties of the two abovementioned conditions is most promising in enhancing the validation experiment.

中文翻译：

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通用液滴蒸发验证试验案例的数值模拟和不确定性量化

代用喷气燃料具有减少航空排放的巨大潜力。引入它们的最大困难是昂贵且冗长的燃料对燃烧性能影响的评估。在目前的工作中，蒸发的真实大小的液滴（D实验和数值研究了在定义明确的垂直层流加热流中的≈80μm）。使用微观双脉冲阴影照相法对几种单一物种和系统选择的常规和替代性多组分喷气燃料进行了液滴直径和速度的测量。结果表明该实验对蒸发是燃料敏感的。在这项研究中，要特别注意未知或不确定的边界和初始条件，它们是数值模型验证中的输入。因此，执行使用多项式混沌展开的非介入式，不确定性仿真来解决这些不确定性。不确定性量化显示总体不确定性很小，足以区分不同的燃料并预测燃料对蒸发的影响。尽管如此，不确定性还是可以忽略的。灵敏度分析表明，蒸发对液滴偏离中心线的偏移以及流入气体温度的不确定性具有很高的灵敏度。减少上述两个条件的不确定性对于增强验证实验是最有希望的。