The in-cylinder flow prior to combustion is considered to be one of the most important aspects controlling the combustion process in an engine. More specifically, the large-scale structures present in the cylinder, so-called tumble and swirl, before compression are believed to play a major role into the mixing and combustion processes. Their development during the intake stroke and their final strength depend mainly (but not only) on the inlet port design. In the present study, the turbulent large-scale structures during the intake stroke are investigated in a unique water-analogue engine where inlet ports and valve timings can easily be configured and tested. The flow field in the cylinder volume is reconstructed through multi-planar stereoscopic particle image velocimetry measurements which reveal a wealth of vortical structures during the stroke’s various phases. The aim of the present paper is to present and show results from a unique setup which can serve as a test bench for optimisation of inlet port designs to obtain a desired vortical pattern in the cylinder after the intake stroke is finished. This setup can simulate the intake stroke in a much more realistic way as compared to a through-flow setup with a fixed valve lift.Graphical Abstract

中文翻译：

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在独特的水模拟发动机模型中解开翻滚和漩涡

燃烧前的缸内流量被认为是控制发动机燃烧过程的最重要方面之一。更具体地说，在压缩之前存在于气缸中的大型结构，即所谓的翻滚和涡流，被认为在混合和燃烧过程中起主要作用。它们在进气冲程期间的发展及其最终强度主要（但不仅）取决于进气口设计。在本研究中，在一个独特的水模拟发动机中研究了进气冲程期间的湍流大型结构，其中进气口和气门正时可以很容易地配置和测试。通过多平面立体粒子图像测速测量重建了圆柱体体积中的流场，这些测量揭示了中风各个阶段的大量涡旋结构。本文的目的是展示和展示一个独特设置的结果，该设置可以用作优化进气道设计的测试台，以便在进气冲程完成后在气缸中获得所需的涡流图案。与具有固定气门升程的通流装置相比，这种装置可以以更真实的方式模拟进气冲程。图形摘要