On The Validation of LES Applied to Internal Combustion Engine Flows: Part 1: Comprehensive Experimental Database

Baum, Elias; Peterson, Brian; Böhm, Benjamin; Dreizler, Andreas

doi:10.1007/s10494-013-9468-6

Cited by 122 publications

(115 citation statements)

References 47 publications

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“…For the swirl view measurements, the Laser beam was converted to a sheet of about 0.5-1 mm thickness by a combination of spherical and cylindrical lenses, fired horizontally through the pentroof of the engine in full optical setup (quartz liner and sapphire piston window); the camera was positioned in front of the 45° mirror that was situated within the Bowditch piston arrangement, see Figure 2 Several aspects of the PIV technique, including practical application, precision and uncertainties were optimised according to [23] in consultation with seminal publications on the specifics of PIV [24][25][26][27][28][29][30][31] and previously published PIV studies focused on internal combustion engine measurements [6][7][8][9][32][33][34]. In this context, Table 3 summarises the system's main settings and several other details of the PIV measurements presented in this paper, e.g.…”

Section: Test Procedures Pivmentioning

confidence: 99%

“…Although early Particle Image Velocimetry (PIV) studies on engine flows had highlighted the issue of bias in the statistical analysis of small batches of engine cycles [1,2], data storage issues and processing time have forced most researchers to use no more than 50-200 cycles for their analysis [3][4][5][6]. More recently kHz range high-speed PIV has been utilised for typical 2D flow mapping but also with volume-based characterisation that can be used for validation of Large Eddy Simulation (LES) of engine flows [7][8][9]. High-speed PIV allows crank-angle resolved measurements to be undertaken and has been shown to give insights into the field of cycle-to-cycle flow variability, including spray-flow and flame-flow interactions [10][11][12][13][14][15][16], nevertheless at the expense of data storage requirements, especially if large numbers of cycles are sought after for statistical analysis.…”

Section: Introductionmentioning

confidence: 99%

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Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

Aleiferis

Behringer

2017

Fuel

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In-cylinder air flow structures are known to play a major role in mixture preparation and engine operating limits for spark-ignition engines. In this paper PIV measurements were undertaken in an optical spark-ignition at 1500 RPM, part-load with 0.5 bar intake plenum pressure. One of the PIV planes was vertical, cutting through the centrally located spark plug (tumble plane). The other plane was horizontal 1 mm below the spark plug ground electrode (swirl plane). The effect of engine head temperature was also examined by using engine-head coolant temperatures of 20 °C and 80 °C. The flow field was examined late in the compression stroke at typical ignition timing. The study was conducted under air-only motoring engine conditions but also under fuelled conditions in the early intake stroke using direct injection of gasoline, iso-octane, ethanol and butanol fuels. The flow field under air-only motored conditions showed velocities between 3-5 m/s predominantly from intake to exhaust. Little differences were observed between hot and cold engine-head temperature; typically ~10% larger mean velocity and turbulent kinetic energy was seen on the intake side. Integral length scales were on the tumble plane between 2-4.5 mm in the vertical and 4-7 mm in the horizontal direction. The swirl view showed scales between 4-10 mm, larger at cold than at hot engine-head conditions. The vertical length scales appeared to be limited by the clearance height, scaling typically by about 10-15%. The horizontal components scaled to the cylinder bore diameter by about 5-12%. The fuel injection process in the early intake stroke led to little differences in the general mean flow structure at ignition timing, except for a small increase in the maximum velocities, ~10%. The turbulent kinetic on the tumble plane was highest towards the exhaust side of the engine under non-fuelled engine conditions but fuel injection resulted in highest values on the intake side. The integral length scales with fuel injection were of the same order of magnitude to those of air only measurements on the tumble plane, but showed distinctly larger areas with length scales up to 9 mm on the swirl plane. Differences between fuels for their fuel specific injection duration were small, with average length scales between 4-6 mm. Ethanol exhibited typically largest scales and butanol smallest.3

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Section: Test Procedures Pivmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

Aleiferis

Behringer

2017

Fuel

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“…The engine design was intended to provide benchmark data at the next logical level beyond the Imperial College data [10], adding essential features of ICE operation such as complete charge transfer processes, continuous operation, and combustion. Complementing the more recent LES calculations noted above, there are experimental data available from measurements within motored and fired four-valve pent roof engines [11,12]. The TCC engine was resurrected in 2010 in the TCC-II version, to renew the fundamental investigation of CCV using experiments in conjunction with the evaluation of three different LES approaches [13].…”

Section: Introductionmentioning

confidence: 99%

TCC-III Engine Benchmark for Large-Eddy Simulation of IC Engine Flows

Schiffmann

Gupta

Reuss

et al. 2015

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-A collaborative effort is described to benchmark the TCC-III engine, and to illustrate the application of this data for the evaluation of sub-grid scale models and valve simulation details on the fidelity of Large-Eddy Simulations (LES). The TCC-III is a spark ignition 4-stroke 2-valve engine with a flat head and piston and is equipped with a full quartz liner for maximum optical access that allows high-speed flow measurements with Particle Image Velocimetry (PIV); the TCC-III has new valve seats and a modified intake-system compared to previous configurations. This work is an extension of a previous study at an engine speed of 800 RPM and an intake manifold pressure (MAP) of 95 kPa, where a one-equation eddy viscosity LES model yielded accurate qualitative and quantitative predictions of ensemble averaged mean and RMS velocities during the intake and compression stroke. Here, experimental data were acquired with parametric variation of engine speed and intake manifold absolute pressure to assess the capability of LES models over a range of operating conditions of practical relevance. This paper focuses on the repeatability and accuracy of the measured PIV data, acquired at 1 300 RPM, at two different MAP (95 kPa and 40 kPa), and imaged at multiple data planes and crank angles. Two examples are provided, illustrating the application of this data to LES model development. In one example, the experimental data are used to distinguish between the efficacies of a one-equation eddy viscosity model versus a dynamic structure one-equation model for the sub-grid stresses. The second example addresses the effects of numerical intake-valve opening strategy and local mesh refinement in the valve curtain.Résumé -Benchmark de moteur de référence TCC-III pour la simulation aux grandes échelles (Large-Eddy Simulations, LES) de l'écoulement dans les moteurs à combustion interne -Un projet collaboratif est décrit, visant à caractériser le moteur TCC-III et à illustrer l'application de ces données pour l'évaluation de modèles de sous-maille et des détails de simulation des soupapes sur la fidélité de simulations aux grandes échelles. Le TCC-III est un moteur à allumage commandé 4 temps à deux

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“…In this study, we consider a four-stroke optical engine, which is operated by the Dreizler group at Technical University of Darmstadt [14]. The engine runs at 800 rpm with iso-octane (C 8 H 18 ) as a surrogate fuel.…”

Section: Methodsmentioning

confidence: 99%

“…In this work, simulations of a four-stroke engine [14] with two intakes and two exhaust valves are performed on two different computational grids with cell sizes of 0.8 mm and 0.5 mm. To avoid the complexity of the mesh generation in a moving engine-geometry, the motion of the piston and the valves are described by Lagrangian particles in combination with an Immersed Boundary Method (IBM) [15].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Numerical Effects on the Flow and Combustion in LES of ICE

Nguyen

Kempf

2017

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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-This work investigates the influence of numerical dissipation on the modeled combustion in Large Eddy Simulations (LES). It is well known that capturing the dynamics of the in-cylinder flow is crucial for engine simulations, as it strongly affects flame propagation. The flame propagation during the power-stroke highly depends on the turbulence level that is developed throughout compression. This turbulence level will be strongly influenced by the accuracy of the numerical schemes employed. Even a small extent of upwinding, filtering, low-order implicit time-stepping, cell-stretching or mapping between grids may affect the flow field, the turbulence level, and hence the turbulent flame speed and the pressure curve. To provide a reference, the LES in-house code PsiPhi is used, which ensures a minimum of dissipation due to high order explicit time-stepping, homogeneous and isotropic filters and cells. Good stability of the code permits the use of a second-order Central Differencing Scheme (CDS) for the transport of momentum, avoiding numerical dissipation. To analyse the effect of numerical dissipation, simulations of a fired engine are performed using different numerical schemes for the convection of momentum. Physical quantities including the total kinetic energy, the velocity gradient, the turbulent viscosity, the in-cylinder pressure, the flame propagation or the burning rate of different test cases are evaluated and compared to each other to show the numerical effects on combustion. Furthermore, the suitability of common LES quality criteria including an energy criterion and viscosity ratio is discussed based on the comparison of simulations with less and more accurate numerics. It is shown that these LES quality indicators can be highly misleading.

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On The Validation of LES Applied to Internal Combustion Engine Flows: Part 1: Comprehensive Experimental Database

Cited by 122 publications

References 47 publications

Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

Modulation of integral length scales of turbulence in an optical SI engine by direct injection of gasoline, iso -octane, ethanol and butanol fuels

TCC-III Engine Benchmark for Large-Eddy Simulation of IC Engine Flows

Investigation of Numerical Effects on the Flow and Combustion in LES of ICE

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