Volumetric measurements of internal flow in an IC engine during intake and compression

该研究项目的目的是对透明内燃机进气和压缩阶段内部流动拓扑的时空演变进行实验研究。在这些流量测量的基础上，获得了关于压缩后期循环变化的性质和结构的更详细的知识。因此，最近发展的基于单视图法的体积PIV测量方法(光场PIV、3D扫描PIV)被应用，它可以避免透明发动机仅使用通过透明活塞头的光路进行三维速度测量的光学访问受限的问题。除了集中在后期压缩和点火阶段的其他实验子项目3-5之外，研究的重点是滚动涡的流动-壁面相互作用及其引起的位置和结构的波动不稳定性。此外，利用流场中流体旋转和流体变形张量的附加信息，对压缩过程中的滚流破裂过程进行了定性，这是在子项目7中的大涡模拟所预测的。

The aim of the proposed research project is the experimental investigation of the spatio-temporal evolution of internal flow topology in a transparent IC engine during the intake and compression phase. Based on these flow measurements, more detailed knowledge is gained on the nature and structure of cycle-to-cycle variations in the late compression phase. Therefore, recently developed volumetric PIV measurement methods based on single-view approach (Light-field PIV, 3D Scanning PIV) are applied, which can circumvent the problems of limited optical access in transparent engines using only the light-path through the transparent piston head for 3D velocimetry. Focus of the studies are the flow-wall interactions and resulting fluctuation instabilities of position and structure of the tumble vortex in addition to the other experimental sub-projects 3-5, which concentrate on the late compression and ignition phase. Furthermore, the additional information of the fluid rotation and fluid deformation tensor in the flow field is used to qualify the process of tumble breakdown during compression, being predicted by the LES simulation in sub-project 7.