A Combined Numerical and Experimental Investigation of Cycle-to-Cycle Variations in an Optically Accessible Spark-Ignition Engine
A Combined Numerical and Experimental Investigation of Cycle-to-Cycle Variations in an Optically Accessible Spark-Ignition Engine
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DOI：
10.1007/s10494-022-00353-7
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发表时间：
2022-08
期刊：
影响因子：
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通讯作者：
Hongchao Chu;C. Welch;Hani Elmestikawy;Shangyi Cao;M. Davidovic;B. Böhm;A. Dreizler;H. Pitsch
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文献类型：
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作者：
Hongchao Chu;C. Welch;Hani Elmestikawy;Shangyi Cao;M. Davidovic;B. Böhm;A. Dreizler;H. Pitsch
本文对一台光学可达火花点火进气道喷射发动机的循环变动进行了数值模拟和试验研究。被认为是一个稳定和不稳定的操作条件。在大涡模拟（LES）中采用了成熟的湍流、燃烧和点火模型。在实验中，通过粒子图像测速技术和火焰成像技术对滚流平面内的速度场进行了高速测量。对缸内压力场、流场、火焰空间分布以及快慢循环条件下的流场进行了详细的比较。考虑到所有周期的变量实现了良好的协议，然而，观察到的条件平均量的一些差异。系统的定量相关性分析所选择的影响变量和CCV之间的，其中的影响变量是从不同的长度尺度（r = 3 mm，12 mm，和43 mm）提取和CCV之间的早期火焰核心发展和后期火焰传播区分。即使最相关的影响参数是不同的两种操作条件下，相干涡结构的位置被发现是重要的CCV的两种情况下。
A combined numerical and experimental investigation is carried out to analyze the cycle-to-cycle variations (CCV) in an optically accessible spark-ignition engine with port fuel injection. A stable and an unstable operating condition is considered. Well-established turbulence, combustion, and ignition models are employed in the large-eddy simulations (LES). High-speed measurements of the velocity field via particle image velocimetry and flame imaging in the tumble plane are conducted in the experiments. A detailed comparison between LES and experiments is carried out, including the in-cylinder pressure, the flow fields, the spatial flame distribution, and the fields conditioned on fast and slow cycles. Good agreement is achieved for the variables considering all cycles; yet, some discrepancies are observed for the conditionally averaged quantities. A systematic quantitative correlation analysis between the selected influencing variables and the CCV is presented, in which the influencing variables are extracted from different length scales (r = 3 mm, 12 mm, and 43 mm) and the CCV are distinguished between the early flame kernel development and later flame propagation. Even though the most relevant influencing parameters are different for the two operating conditions, the location of the coherent vortex structure is found to be important for the CCV of both cases.