CFD Simulations AC2-10: Difference between revisions
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Revision as of 15:18, 12 October 2018
Internal combustion engine flows for motored operation
Application Challenge AC2-10 © copyright ERCOFTAC 2024
CFD Simulations
Introduction
The TU Darmstadt engine has been investigated by three different groups using LES (Large Eddy Simulation) and hybrid URANS(unsteady Reynolds-averaged Navier-Stokes)/LES. These research groups are located at Technische Universit\"{a}t Bergakademie Freiberg (TUBF), Universit\"{a}t Duisburg-Essen (UDE) and Technische Universit\"{a}t Darmstadt (TUD). In the follow, the different approaches will be presented, including general information about the code and the physical modelling, computational domain and mesh treatment, initial and boundary conditions and computational requirements. Additional and detailed information can be found in the scientific papers listed in Table \ref{tab:simulations}.
Overview of simulation
Test data for the motored case is available at three different operating points. A test case considering an engine speed of 800 RPM is investigated in the numerical studies, which are summarized in Table \ref{tab:simulations}.
Group | Approach | CFD Code / Publication |
---|---|---|
TUBF | URANS / LES | Ansys CFX R16.0 / Buhl et al. [9, 10] |
UDE | LES | OpenFoam-2.3.x / Janas et al. [21] |
TUD | LES | KIVA-4mpi / He et al. [20] |
Further, simulations were carried out by Nguyen et al. \cite{Nguyen2016} and Baumann et al. \cite{Baumann2014}, which are not part of this comparison.
CFD codes
In the following, the governing equations, turbulence modelling and solver are described for the three different CFD codes.
Ansys CFX R16.0
For this compressible case, the filtered governing equations for mass, momentum and total enthalpy are solved. They are defined as:
(4.1) | |
(4.2) | |
(4.3) |
with the thermal conductivity and the turbulent Prandtl number (set to 0.9 in the following). A non-density-weighted filtered variable is denoted by , while is the density-weighted filtered variable. This system is complemented by the filtered equation of state for perfect gases, defined as:
(4.4) |
with the molecular weight and the universal gas constant . The eddy viscosity () is calculated based on the scale-adaptive simulation (SAS-SST) turbulence model \cite{Menter2010}. In case of insufficient spatial or temporal resolution (for a SRS), it reverts to the SST model \cite{Menter1994} and maintains a valid base of modelling. Its key element is the von K\'arm\`an length scale \cite{Rotta2010} (), introduced into the scale-determining equation. In unstable flows, adjusts the eddy viscosity to a level which allows the formation of a turbulent spectrum \cite{Menter2010,Travin2002,Schaefer2010,Lucius2010}. is defined as
|align="right"|(4.5) |
Contributed by: Carl Philip Ding,Rene Honza, Elias Baum, Andreas Dreizler — Fachgebiet Reaktive Strömungen und Messtechnik (RSM),Technische Universität Darmstadt, Germany
Contributed by: Brian Peterson — School of Engineering, University of Edinburgh, Scotland UK
Contributed by: Chao He , Wibke Leudesdorff, Guido Kuenne, Benjamin Böhm, Amsini Sadiki, Johannes Janicka — Fachgebiet Energie und Kraftwerkstechnik (EKT), Technische Universität Darmstadt, Germany
Contributed by: Peter Janas, Andreas Kempf — Institut für Verbrennung und Gasdynamik (IVG), Lehrstuhl für Fluiddynamik, Universität Duisburg-Essen, Germany
Contributed by: Stefan Buhl, Christian Hasse — Fachgebiet Simulation reaktiver Thermo-Fluid Systeme (STFS), Technische Universität Darmstadt, Germany; former: Professur Numerische Thermofluiddynamik (NTFD), Technische Universität Bergakademie Freiberg, Germany
© copyright ERCOFTAC 2018