A multispectral, extinction-based diagnostic for drop sizing in optically dense diesel sprays
A multispectral, extinction-based diagnostic for drop sizing in optically dense diesel sprays
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DOI：
10.1177/1468087419866034
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发表时间：
2020-01
影响因子：
2.5
通讯作者：
F. Poursadegh;O. Bibik;Boni F. Yraguen;C. Genzale
中科院分区：
文献类型：
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作者：
F. Poursadegh;O. Bibik;Boni F. Yraguen;C. Genzale
柴油喷雾为液体场的详细定量测量提供了一个具有挑战性的环境，迄今为止，在发动机燃烧网络 (ECN) 柴油喷雾系列中表征液滴尺寸的努力很少。液滴尺寸诊断，包括光学显微镜和超小角度 X 射线散射 (USAXS)，最近已在喷雾 A/D ECN 活动中得到证实，但验证这些结果的数据很少。因此，这项工作旨在扩展液相场上可用的 ECN 数据，并为评估以前的 ECN 液滴尺寸测量提供新的比较数据集。特别是，这项工作提出了一种双波长视线消光测量方法的开发，用于检查高压燃料喷雾中的液体体积分数和相应的液滴场。这里，使用以 10.6 μm 和 0.633 μm 发射的激光的消光进行测量。为了能够量化喷雾光学密集区域中的液体场，开发了传递函数来考虑多重散射的影响。然后，将开发的诊断应用于不同燃油轨压力和大气室条件下 ECN Spray A 和 Spray D 喷油器的正十二烷喷雾。总体而言，结果显示与使用 USAXS 测量的液滴尺寸以及使用我们小组开发的散射吸收测量比 (SAMR) 技术的最新测量结果相当一致。尤其是靠近喷雾周边的情况，观察到测量的索特平均直径的平均差异小于 40%。尽管如此，在靠近喷射中心线的不同诊断中观察到液滴尺寸之间存在明显差异（即 Spray D 喷射器的可用数据之间几乎 100% 的差异）。此外，所提出的诊断显示了喷雾稀释区域的改进能力，其中基于 X 射线的诊断通常受到高噪声和低信号灵敏度的影响。
Diesel sprays present a challenging environment for detailed quantitative measurement of the liquid field, and to date, there have been only a few efforts to characterize drop sizes within the family of Engine Combustion Network (ECN) diesel sprays. Drop sizing diagnostics, including optical microscopy and Ultra-Small Angle X-ray Scattering (USAXS), have been recently demonstrated in Spray A/D ECN activities, but little data exist to validate these results. This work therefore seeks to extend the available ECN data on the liquid phase field and provide a new comparative data set for assessment of previous ECN drop sizing measurements. In particular, this work presents the development of a two-wavelength, line-of-sight extinction measurement to examine liquid volume fraction and the corresponding droplet field in high-pressure fuel sprays. Here, extinction of lasers emitting at 10.6 μm and 0.633 μm are used for the measurement. To enable quantification of the liquid field in optically dense regions of the spray, a transfer function is developed to account for the influence of multiple scattering. The developed diagnostic is then applied to n-dodecane sprays from the ECN Spray A and Spray D injectors at varying fuel rail pressures and atmospheric chamber condition. Overall, the results show a reasonable agreement with droplet sizes measured using USAXS, as well as from more recent measurements using a Scattering-Absorption Measurement Ratio (SAMR) technique also developed in our group. This is particularly the case near the spray periphery, where on average, less than 40% difference in the measured Sauter mean diameter is observed. Nonetheless, an apparent discrepancy is observed between drop sizes from different diagnostics close to the jet centerline (i.e. nearly 100% difference between available data for Spray D injector). Moreover, the presented diagnostic shows an improved capability in the dilute regions of the spray, where x-ray-based diagnostics are generally subject to high noise and low signal sensitivity.