Automatic Mech Generation for Full-Cycle CFD Modeling of IC Engines: Application to the TCC Test Case 2014-01-1131

The definition of a robust methodology to perform a full-cycle CFD simulation of IC engines requires as first step the availability of a reliable grid generation tool, which does not only have to guarantee a high quality mesh but also has to prove to be efficient in terms of required time. In this work the authors discuss a novel approach entirely based on the OpenFOAM technology, in which the available 3D grid generator was employed to automatically create meshes containing hexahedra and split-hexahedra from triangulated surface geometries in Stereolithography (STL) format. The possibility to introduce local refinements and boundary layers makes this tool suitable for IC engine simulations. Grids are sequentially generated at target crank angles which are automatically determined depending on user specified settings such as maximum mesh validity interval and quality parameters like non-orthogonality, skewness and aspect ratio. This ensures high quality grids for the entire cycle and requires a very reduced amount of user time. The proposed approach has been introduced into the Lib-ICE code, which is a set of libraries and solvers based on the OpenFOAM technology and developed by the authors for IC engine modeling. Experimental validation was carried out by simulating the full cycle in the so-called TCC (Transparent Combustion Chamber) engine [1, 2], whose experimental data are available through the Engine Combustion Network database (ECN). In particular, a detailed comparison between computed and experimental in-cylinder pressure, turbulence intensity distribution and velocity field was performed so that it was possible to assess the requirements in terms of minimum mesh size and numerical method accuracy to be employed with the proposed methodology.