Large-Eddy Simulation of in-Cylinder Flows

Abstract

RŽsumŽ Ñ Simulation ˆ grande Žchelle des Žcoulements internes dans les moteurs Ñ Les progr•s des mod•les physiques, des mŽthodes numŽriques et de la puissance de calcul permettent quÕon puisse prendre en considŽration les simulations ˆ grande Žchelle (LES) pour le calcul des Žcoulements turbulents dans les moteurs. La synth•se prŽsentŽe comprend : une discussion sur la LES montrant ses diffŽrences avec la modŽlisation aux moyennes de Reynolds (RANS) ; les motivations pour passer ˆ la LES pour les Žcoulements internes aux moteurs ; des rŽsultats quantitatifs pour deux configurations de moteur entra"nŽ. Des mod•les de sous-maille Ç dynamique È des tenseurs sont dŽveloppŽs, par ailleurs, nous discutons des rŽsultats donnŽs par deux approches numŽriques diffŽrentes. En comparaison avec la mŽthodologie RANS, la LES requiert peu dÕapports empiriques, donne plus de dŽtails sur la structure de lÕŽcoulement dans le cylindre et permet lÕanalyse de phŽno-m•nes jusquÕalors inaccessibles, comme les variations cycliques. Mots-clŽs : simulation, LES, moteurs. Abstract Ñ Large-Eddy Simulation of In-Cylinder Flows Ñ Advances in physical models, numerical methods, and computational power together have brought large-eddy simulation (LES) to the point where it warrants serious consideration for computing in-cylinder turbulent flows. This article includes: a discussion of LES and how it differs from Reynolds-averaged Navier Stokes (RANS) modeling

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

“…This has been especially true for evaluating the averagecycle behavior of new engine concepts [1]. With increased computational capabilities, more details, such as cyclic variability (Cycle-to-Cycle Variation, CCV) can be addressed using multi-cycle Large-Eddy Simulation (LES), that has been evolving since the 1990s [2]. Since then, LES has been used to simulate flow and combustion in modern engine concepts such as four-valve pent-roof spark-ignition, Diesel, and HCCI engines [3][4][5][6][7][8][9].…”

State of the Art of Multi-Dimensional Modeling of Engine Reacting Flows

“…Indications that the benefits of LES may already outweigh the disadvantages can be found in the references cited above, which include the paper by Howarth [22] in the present proceedings. This study clearly demonstrates that LES is able to produce superior predictions of induction-generated flow that any of the current RANS approaches, including full Reynolds stress transport models.…”

“…Generally speaking it is poorest during the induction stroke, especially with regard to the turbulence intensity, which is usually substantially underpredicted [21,22]. Better and often satisfactory agreement is however obtained later in the engine cycle (e.g.…”

“…In the meantime however the alternative LES framework has also been developed and assessed for engine simulation, with promising results [22,61].…”

Numerical Methods and Turbulence Modeling for LES of Piston Engines: Impact on Flow Motion and Combustion

“…Besides, many promising results have been obtained with such a set-up. For example, previous works conducted at IFP Energies nouvelles and CERF-ACS using the Lax-Wendroff scheme and the classical constant coefficient Smagorinsky model have demonstrated the great potential of LES for solving complex problems in piston engines, notably its ability to help understanding CCV sources [4,13,17] and to build phenomenological models for engine control development [18]. However, it is well known that both numerics and turbulence models can have a huge impact on the simulation results.…”