A New Methodology to Analyze Cycle-to-Cycle Aerodynamic Variations

Baby, Xavier; Dupont, A.; Ahmed, Afíf; Deslandes, Willy; Charnay, G.; Michard, Marc

doi:10.4271/2002-01-2837

Cited by 34 publications

(25 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 17 presents the energy distribution of the ten highest energy modes found in the POD as a function of the C A. The largest part of the energy (∼70%) is contained in the first mode which corresponds to the mean flow (similar results were found in [1]). The other modes reveal the velocity fluctuations and their corresponding energy denotes their level.…”

Section: Aerodynamics Variationssupporting

confidence: 63%

Large Eddy Simulation of a Motored Single-Cylinder Piston Engine: Numerical Strategies and Validation

Enaux

Granet

Vermorel

et al. 2010

Flow Turbulence Combust

View full text Add to dashboard Cite

This paper describes a compressible Large Eddy Simulation (LES) used to investigate cyclic variations for nonreacting flow in an optical single cylinder engine setup. The simulated operating point is part of a large experimental database designed to validate LES for cycle-to-cycle prediction, and constitutes a first step towards the realization of fired operating points. The computational domain covers almost the whole experimental setup (intake and exhaust plenums, intake and exhaust ducts, cylinder) to account for acoustic phenomena. The assessment of the computation is performed in two regions of the domain: the intake and exhaust duct predictions are compared to the results of a Helmholtz solver and the experiment (pressure transducers and Particle Image Velocimetry (PIV)) while the in-cylinder dynamics are compared to PIV measurements. The ability of the B. Enaux · V. Granet (B) · O. Vermorel 154 Flow Turbulence Combust (2011) 86:153-177 developed methodology to capture the correct level of cycle-to-cycle variations is demonstrated considering in-cylinder pressure and velocity fields predictions. Cycleto-cycle variations in velocity are highlighted and localized using a proper orthogonal decomposition analysis.

show abstract

Section: Aerodynamics Variationssupporting

confidence: 63%

Large Eddy Simulation of a Motored Single-Cylinder Piston Engine: Numerical Strategies and Validation

Enaux

Granet

Vermorel

et al. 2010

Flow Turbulence Combust

View full text Add to dashboard Cite

show abstract

“…In this paper, cyclic flow variations are investigated using Proper Orthogonal Decomposition (POD), which has been used previously to differentiate between cyclic flow variations and turbulence. Baby et al [5] used the first mode to represent the mean in-cylinder velocity. Modes 2-4 are reconstructed to represent the cyclic variability, and the rest of the modes represents the turbulence.…”

Section: Introductionmentioning

confidence: 99%

Evaluating Large-Eddy Simulation (LES) and High-Speed Particle Image Velocimetry (PIV) with Phase-Invariant Proper Orthogonal Decomposition (POD)

Abraham

Liu

Haworth

et al. 2013

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

View full text Add to dashboard Cite

and available online here Cet article fait partie du dossier thématique ci-dessous publié dans la revue OGST, Vol. 69, n°1, et téléchargeable ici D o s s i e rDOSSIER Edited by/Sous la direction de : C. Angelberger IFP Energies nouvelles International Conference / Les Rencontres Scientifiques d'IFP Energies nouvelles LES4ICE 2012 -Large Eddy Simulation for Internal Combustion Engine FlowsLES4ICE 2012 -La simulation aux grandes échelles pour les écoulements dans les moteurs à combustion interne Oil & Gas Science and Technology -Rev. IFP Energies nouvelles, Vol. 69 (2014) Une POD invariante en phase a e´te´applique´e aux donne´es combine´es de vitesse PIV et LES pour tous les angles de vilebrequin, afin d'e´tudier l'e´volution de l'e´coulement en fonction de l'angle de vilebrequin. Les conclusions issues des deux diffe´rentes transformations e´nerge´tiques sont contraste´es. Lorsque l'e´nergie de chaque champ de vitesse est normalise´e, les re´sultats de la POD invariante en phase sont centre´s sur les diffe´rences de structure d'e´coulement et leur e´volution. Par ailleurs, lorsque l'e´nergie de chaque champs de vitesse est conserve´e, les re´sultats de la POD invariante en phase prennent aussi en compte les diffe´rences d'e´nergie entre les donne´es PIV et LES.Abstract -Evaluating Large-Eddy Simulation (LES) and High-Speed Particle Image Velocimetry (PIV) with Phase-Invariant Proper Orthogonal Decomposition (POD) -This study is part of a program to understand the stochastic variations in IC engine flows; in particular, it is a comparison of measured (PIV) and computed (LES) velocity from multiple cycles of the same motored engine.Comparison procedures included traditional RANS (Reynolds Averaged Navier-Stokes) decomposition (ensemble-averaged and RMS (Root Mean Square) velocity), phase-dependent, and phaseinvariant POD. Phase-dependent POD was performed on the PIV and LES samples separately and on the combined samples, thus creating separate or a single POD mode sets, respectively. The phaseinvariant POD was performed both on normalized snapshots and on snapshots where the original energy was conserved.Initial comparisons of the mass-specific kinetic energies of the ensemble average and RMS velocities revealed that the PIV and LES data sets differed significantly during most of the intake stroke. This discrepancy was quantified first by comparing the relevance indices calculated between ensemble average velocity fields and, second, using phase-dependent POD, which quantified cycle-to-cycle flow variations of the RANS average and turbulence. Phase-dependent POD was applied separately to the PIV and LES data sets during the intake stroke (76°ATDCE, After Top Dead Center Exhaust), where the intake-valve jet is strong and the PIV and LES data were earlier found to be significantly different. The cyclic variability of the LES ensemble average was estimated to be significantly higher than that of the PIV data set. POD was also applied to the combined sample of LES and PIV snapshots for quantitative comparison creatin...

show abstract

“…Compared to the effects of CCV, like the variation of the peak pressure during combustion being directly accessible both in experiments and simulations, the relevant underlying physics are not yet fully identified despite a significant number of investigations, [13][14][15][16][17] and references therein as well review articles [18,19].…”

Section: Definition Of Cyclic Variationsmentioning

confidence: 99%

“…Corresponding structures are indicated by the same color. Figure 10c shows the large-scale fluctuations calculated by Equation (13) and Figure 10d shows the 2nd POD mode. Interestingly, the structures of the large-scale fluctuations and the 2nd POD mode appear to be almost identical, which can be explained by the higher energy content (more than 50% compared to mode 3) of the 2nd mode.…”

Section: Identification Of Cyclic Variationsmentioning

confidence: 99%

Identification of Large-Scale Structure Fluctuations in IC Engines using POD-Based Conditional Averaging

Buhl

Hartmann

Hasse

2015

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

View full text Add to dashboard Cite

-Cycle-to-Cycle Variations (CCV) in IC engines is a well-known phenomenon and the definition and quantification is well-established for global quantities such as the mean pressure. On the other hand, the definition of CCV for local quantities, e.g. the velocity or the mixture distribution, is less straightforward. This paper proposes a new method to identify and calculate cyclic variations of the flow field in IC engines emphasizing the different contributions from largescale energetic (coherent) structures, identified by a combination of Proper Orthogonal Decomposition (POD) and conditional averaging, and small-scale fluctuations. Suitable subsets required for the conditional averaging are derived from combinations of the the POD coefficients of the second and third mode. Within each subset, the velocity is averaged and these averages are compared to the ensemble-averaged velocity field, which is based on all cycles. The resulting difference of the subset-average and the global-average is identified as a cyclic fluctuation of the coherent structures. Then, within each subset, remaining fluctuations are obtained from the difference between the instantaneous fields and the corresponding subset average. The proposed methodology is tested for two data sets obtained from scale resolving engine simulations. For the first test case, the numerical database consists of 208 independent samples of a simplified engine geometry. For the second case, 120 cycles for the well-established Transparent Combustion Chamber (TCC) benchmark engine are considered. For both applications, the suitability of the method to identify the two contributions to CCV is discussed and the results are directly linked to the observed flow field structures.Résumé -Identification de fluctuations de structure aux grandes échelles dans les moteurs à combustion interne utilisant des moyennes conditionnelles basées sur la POD -Les variations cycle à cycle (VCC) dans les moteurs à combustion interne sont un phénomène bien connu, et leur définition et quantification sont bien établies pour des quantités globales telles que la pression moyenne. Toutefois, la définition des VCC pour des quantités locales, par exemple la vitesse ou le mélange, est moins simple. Le présent article propose une nouvelle méthode visant à identifier et à calculer des variations cycliques de l'écoulement dans les moteurs à combustion interne, en mettant l'accent sur les différentes contributions provenant de structures énergétiques aux grandes échelles (cohérentes), identifiées en combinant la détermination d'une moyenne conditionnelle et par décomposition orthogonale aux valeurs propres (Proper Orthogonal Decomposition, POD) et de fluctuations aux petites échelles. Des sous-ensembles adaptés requis pour l'établissement d'une moyenne conditionnelle sont tirés de la combinaison de coefficients POD des second et troisième modes. Dans chaque sous-ensemble, la vitesse est moyennée et ces moyennes sont comparées à la moyenne d'ensemble du champ de vitesse basée sur l'ensemble d...

show abstract

A New Methodology to Analyze Cycle-to-Cycle Aerodynamic Variations

Cited by 34 publications

References 27 publications

Large Eddy Simulation of a Motored Single-Cylinder Piston Engine: Numerical Strategies and Validation

Large Eddy Simulation of a Motored Single-Cylinder Piston Engine: Numerical Strategies and Validation

Evaluating Large-Eddy Simulation (LES) and High-Speed Particle Image Velocimetry (PIV) with Phase-Invariant Proper Orthogonal Decomposition (POD)

Identification of Large-Scale Structure Fluctuations in IC Engines using POD-Based Conditional Averaging

Contact Info

Product

Resources

About