Injection characteristics and fuel-air mixing process of ammonia jets in a constant volume vessel
Injection characteristics and fuel-air mixing process of ammonia jets in a constant volume vessel
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定容容器内氨射流喷射特性及油气混合过程
DOI：
10.1016/j.fuel.2021.121408
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发表时间：
2021-11
期刊：
影响因子：
7.4
通讯作者：
Dawei Wu
中科院分区：
文献类型：
--
作者：
Zhifei Zhang;Tie Li;Ren Chen;Ning Wang;Yijie Wei;Dawei Wu
直接喷射气态氨是发动机满足零碳排放的一种可能方式。本研究首次对氨喷嘴的喷射特性和燃料-空气混合过程进行了研究。用纹影系统表征了氨喷流的宏观行为，包括喷嘴穿透和喷射角。此外，还利用LIBS定量测量了氨喷嘴的燃料浓度，以研究燃料与空气的混合过程。根据喷嘴侵彻的时间演化规律，提出了喷射初期、准稳定阶段和两次喷射持续时间后的t、t0.5和(t-τ)0.25三个阶段的相关性，并对其机理进行了详细的讨论。研究了喷油压力和环境压力对喷嘴侵彻和喷射角以及燃料浓度分布的影响。随着喷油压力的增加，喷嘴穿透深度和燃料浓度增加，但喷射角减小。环境压力的影响是相反的，这表明氨射流的发展是由喷射与环境压力之比决定的。对氨喷流和甲烷喷流进行了比较。结果表明，它们具有非常相似的尖端侵彻和喷射角，以及在喷射轴上几乎相同的燃料摩尔分数。然而，氨喷流中的当量比明显低于甲烷喷流中的当量比，这导致了氨和甲烷喷流中可燃混合物的不同分布。
The direct-injection of gaseous ammonia is a possible way to fuel engines to meet the scenario of zero-carbon emission. In this study, for the first time, the injection characteristics and fuel–air mixing process of ammonia jets are investigated. A Schlieren system is employed to characterize the macroscopic behavior of ammonia jets including the tip penetration and jet angle. Besides, the fuel concentrations of ammonia jets are quantitatively measured by LIBS to investigate the fuel–air mixing processes. According to the time evolutions of jet tip penetration, the three-stage behavior, namely the t, t0.5and (t-τ)0.25dependence corresponding to the early stage of injection, quasi-steady stage and after two times of injection duration respectively, are proposed and the mechanisms are discussed in detail. The effects of both injection and ambient pressures on the tip penetration and jet angle, as well as the fuel concentration distributions are investigated. The increased injection pressure leads to increases in the tip penetration and fuel concentration but decreases in the jet angle. The effects of ambient pressure are opposite, indicating that the ammonia jet development is governed by the injection-to-ambient pressure ratio. The comparisons between ammonia and methane jets are conducted. The results show they have quite similar tip penetrations and jet angles, as well as the nearly equivalent fuel mole fractions at the jet axis. However, the equivalence ratios in ammonia jets are significantly lower than those in methane jets, leading to the distinct flammable mixture distributions in ammonia and methane jets.
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影响因子：
9
作者：
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