X-ray phase contrast imaging is conducted at 90,517 Hz on a fuel spray to characterize the breakup of the bulk fuel into ligaments and indiv¬idual droplets in a single-sector, swirl-stabilized combustor under reacting conditions. Phase contrast imaging is used to qualitatively assess spray breakup for two fuels: Jet-A, which represents a normal viscosity fuel, and a blend of JP-5 (64%) and farnesane (36% by volume), which represents a high viscosity fuel, at three fuel flow rates and two air inlet temperatures. Time-series images of the fuels show that atomization occurs much more rapidly at higher fuel pressure with thinner ligaments being rapidly shredded. The high viscosity fuel is qualitatively observed to have markedly longer, thicker ligaments and larger droplet diameters after the primary breakup than the normal viscosity fuel. Using an image processing and droplet quantification strategy, the mean droplet velocity magnitudes were found to decrease with decreasing fuel pressure and fuel flow rate. The increase in preheat temperature from 323 K to 370 K results in an increase in the mean droplet velocity magnitude and a decrease in numerical average and Sauter mean diameter, indicating improved atomization. The high viscosity fuel was found to have larger average droplet diameters at each condition than the normal viscosity fuel. The increased preheat is found to enhance the combustion efficiency, which is hypothesized to couple with the improved atomization due to the higher combustion temperatures. This indicates the importance of examining spray atomization and breakup under realistic combusting conditions for relevant fuels as the heat release directly couples

中文翻译：

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燃烧条件下喷气燃料喷雾破碎的高速相衬成像

在燃料喷雾器上以90,517 Hz进行X射线相衬成像，以表征在反应条件下散装燃料在单扇旋流稳定燃烧器中分解成韧带和单个液滴的特征。相衬成像用于定性评估两种燃料的喷雾破裂：Jet-A（代表普通粘度的燃料）和JP-5（占64％）和法呢烷（占体积的36％）的混合物，代表高粘度燃油，三个燃油流量和两个进气温度。燃料的时间序列图像显示，在较高的燃料压力下，雾化发生得更快，而较细的韧带则被迅速切碎。定性观察到，高粘度燃料一次破碎后比正常粘度燃料具有更长，更厚的韧带和更大的液滴直径。使用图像处理和液滴定量策略，发现平均液滴速度大小会随着燃料压力和燃料流速的降低而降低。预热温度从323 K增加到370 K，导致平均液滴速度大小增加，数值平均值和Sauter平均直径减小，表明雾化得到改善。发现高粘度燃料在每种条件下均比正常粘度燃料具有更大的平均液滴直径。已发现增加的预热可增强燃烧效率，据推测，由于较高的燃烧温度，燃烧效率与雾化改善有关。这表明在实际燃烧条件下检查相关燃料的喷雾雾化和分解的重要性，因为放热直接耦合