Internal combustion engine flows for motored operation

Application Challenge AC2-10 © copyright ERCOFTAC 2024

Abbreviations

ALE	Arbitrary Lagrangian-Eulerian
aTDC	after top dead center
bTDC	before top dead center
BDC	bottom dead center
CA	crank angle
CAD	crank angle degreeCCD charge-coupled device
CCV	cycle-to-cycle variation
CDS	central differencing scheme
CFD	computational fluid dynamics
CFL	Courant-Friedrichs-Lewy
ENO	Essentially Non-Oscillatory
ERG	exhaust-gas-recirculation
EVC	exhaust valve closing
EVO	exhaust valve opening
HS-PIV	high speed particle image velocimetry
IC	internal combustion
IVC	intake valve closing
IVO	intake valve opening
LES	large eddy simulation
MRV	magnetic resonance velocimetry
PIV	particle image velocimetry
POV	field-of-view
QSOU	quasi-second-order upwind
QUICK	Quadratic Upwind Interpolation for Convective Kinematics
RANS	Reynolds-averaged Navier-Stokes
RMS	root mean square
RPM	rounds per minute
SAS	scale-adaptive simulation
SRS	scale-resolving simulation
SST	shear stress transport
TDC	top dead center
TUBF	Technische Universität Bergakademie Freiberg
TUD	Technische Universität Darmstadt
TVD	total variation diminishing
UDE	Universität Duisburg-Essen
URANS	unsteady Reynolds-averaged Navier-Stokes
WG	wall-guided

Description

Introduction

The TU Darmstadt engine is an optically accessible single cylinder spark-ignition direct injection engine. It is embedded in an especially designed test bench to provide well characterized boundary conditions and reproducible engine operation. A reproducible engine operation is needed to characterize the variety of in-cylinder processes and is a prerequisite for any comparison of experiments and simulations. The in-cylinder processes are characterized using advanced laser-diagnostics to provide measurements at high spatial and temporal resolutions. The aim of this effort is, to build up a comprehensive data set

to give insights into the underlying physics for a better understanding of the relevant in-cylinder processes and
for the validation of CFD simulations especially for large eddy simulations (LES).

The validation of CFD simulations for IC engines requires a variety of physical and chemical quantities and a comprehensive dataset consisting of systematic hierarchical sub-datasets. Such a validation sequence typically starts with the comparison of the non-reacting flow field and increases complexity stepwise by the addition of processes such as, combustion of perfect homogeneous air/fuel mixtures, in-cylinder mixture preparation using direct-injection and combustion of these mixtures. The presented test case is part of an ongoing effort at TU Darmstadt aiming for a detailed characterization of engine combustion addressing the non-reacting flow field \cite{Baum2014,Baum2013,Zentgraf2016}, combustion of homogenous air/fuel mixtures \cite{Peterson2015} and mixture preparation by direct injection \cite{Peterson2017}. The here presented test-case includes the sub-dataset on the non-reacting flow field (motored engine operation) providing a comprehensive data set on the first two statistical moments of flow velocities, spatial flow structures, and the dynamics of the turbulent in-cylinder flow field. The following sections summarize the work which has been presented within \cite{Baum2014}. Further details on the experimental setup and flow field data can be found in \cite{Baum2014,Baum2013,Zentgraf2016}. Additionally, simulation results obtained from three investigations using LES (Large Eddy Simulation) and hybrid URANS (unsteady Reynolds-averaged Navier-Stokes)/LES described in section \ref{sec:simulation} are presented and compared with experimental data, see section \ref{sec:evaluation}.

Relevance to industrial sector

Design or assessment parameters

Engine test bench

The engine test bench allows conditioning the intake air in terms of pressure, temperature and gas composition, port fuel injection of liquid and gaseous fuels, direct-injection, as well as reliable boundary condition control and measurement. Further, the intake and exhaust systems were designed to provide reproducible thermodynamic and flow boundary conditions and simplified meshing for three-dimensional engine flow simulations. Figure \ref{fig:testbench} shows a schematic of the engine test bench from the intake to the exhaust plenum. It shows the locations for which thermodynamic conditions (pressure and temperature) were measured during engine operation.

Figure 2: Engine test bench.

Engine

Flow physics and Fluid Dynamics Data

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