The stringent emission regulations have motivated the development of cleaner fuels as diesel surrogates. However, their different physical-chemical properties make the study of their behavior in compression ignition engines essential. In this sense, optical techniques are a very effective tool for determining the spray evolution and combustion characteristics occurring in the combustion chamber. In this work, quantitative parameters describing the evolution of diesel-like sprays such as liquid length, spray penetration, ignition delay, lift-off length and flame penetration as well as the soot formation were tested in a constant high pressure and high temperature installation using schlieren, OH∗ chemiluminescence and diffused back-illumination extinction imaging techniques. Boundary conditions such as rail pressure, chamber density and temperature were defined using guidelines from the Engine Combustion Network (ECN). Two paraffinic fuels (dodecane and a renewable hydrotreated vegetable oil (HVO)) and two oxygenated fuels (methylal identified as OME₁ and a blend of oxymethylene ethers, identified as OME_x) were tested and compared to a conventional diesel fuel used as reference. Results showed that paraffinic fuels and OME_x sprays have similar behavior in terms of global combustion metrics. In the case of OME₁, a shorter liquid length, but longer ignition delay time and flame lift-off length were observed. However, in terms of soot formation, a big difference between paraffinic and oxygenated fuels could be appreciated. While paraffinic fuels did not show any significant decrease of soot formation when compared to diesel fuel, soot formed by OME₁ and OME_x was below the detection threshold in all tested conditions.

中文翻译：

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发动机燃烧网络喷雾A条件下加氢处理植物油和甲醛醚对主喷雾和燃烧特性影响的实验研究。

严格的排放法规激励了柴油替代品清洁燃料的发展。然而，它们不同的物理化学特性使得研究其在压燃式发动机中的性能至关重要。从这个意义上讲，光学技术是一种非常有效的工具，可用于确定在燃烧室内发生的喷雾演变和燃烧特性。在这项工作中，描述了柴油样喷雾演变的定量参数，例如液体长度，喷雾渗透，点火延迟，升空长度和火焰渗透以及烟灰的形成，这些参数是在恒定的高压和高温装置下使用schlieren，OH *化学发光和扩散背照式消光成像技术。边界条件，例如轨道压力，室密度和温度是根据发动机燃烧网络（ECN）的指南定义的。两种链烷烃燃料（十二烷和可再生加氢处理植物油（HVO））和两种氧化燃料（甲基被鉴定为OME）_{测试了图1的}样品和甲醛醚的混合物，将其标识为OME _x），并与用作参考的常规柴油进行了比较。结果表明，就整体燃烧指标而言，石蜡燃料和OME _x喷雾具有相似的行为。在OME ₁的情况下，观察到较短的液体长度，但观察到较长的点火延迟时间和火焰剥离长度。然而，就烟灰形成而言，可以理解石蜡燃料和含氧燃料之间的巨大差异。尽管与柴油相比，链烷烃燃料的烟灰形成没有明显减少，但在所有测试条件下，OME ₁和OME _x形成的烟灰均低于检测阈值。