Extension of Lagrangian-Eulerian Spray Modeling: Application to High Pressure Evaporating Diesel Sprays

Béard, P.; Duclos, J. M.; Habchi, C.; Bruneaux, Gilles; Mokaddem, K.; Baritaud, T.

doi:10.4271/2000-01-1893

Cited by 60 publications

(31 citation statements)

References 23 publications

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“…Hieber [4] investigated the grid dependency of predicted spray penetration in KIVA code, and implemented a Void Fraction Compensation method to help correct under-resolution. Béard et al [5,6] observed that numerical diffusion over-predicted the rate of momentum exchange between the gas and liquid phases, and proposed the CLE method. Nordin [7] , Xu [8] and Wen [9] also found the grid dependency in KIVA.…”

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confidence: 98%

Algorithms for improving accuracy of spray simulation

Zhang

Xiao

et al. 2007

Chin. Sci. Bull.

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Fuel spray is the pivotal process of direct injection engine combustion. The accuracy of spray simulation determines the reliability of combustion calculation. However, the traditional techniques of spray simulation in KIVA and commercial CFD codes are very susceptible to grid resolution. As a consequence, predicted engine performance and emission can depend on the computational mesh. The two main causes of this problem are the droplet collision algorithm and coupling between gas and liquid phases. In order to improve the accuracy of spray simulation, the original KIVA code is modified using the cross mesh droplet collision (CMC) algorithm and gas phase velocity interpolation algorithm. In the constant volume apparatus and D.I. diesel engine, the improvements of the modified KIVA code in spray simulation accuracy are checked from spray structure, predicted average drop size and spray tip penetration, respectively. The results show a dramatic decrease in grid dependency. With these changes, the distorted phenomenon of spray structure is vanished. The uncertainty in predicted average drop size is reduced from 30 to 5 μm in constant volume apparatus calculation, and the uncertainty is further reduced to 2 μm in an engine simulation. The predicted spray tip penetrations in engine simulation also have better consistency in medium and fine meshes. droplet collision algorithm, coupling between gas and liquid phases, accuracy of spray simulation, spray structure, average drop size, spray tip penetrationIn diesel engine and direct injection gasoline engine, the fuel spray, atomization, evaporation and mixing with air are significant to the combustion and emission of engine. Therefore, the simulation of direct injection engine requires accurate treatment of the spray. Currently, KIVA is the most widely used CFD code in engine simulation. Though KIVA is constructed via good engineering practice and is a laudable achievement, the code is severely grid-dependent. The simulation errors caused by grid dependency are possibly more serious than the errors caused by physical uncertainty, on the order of one-hundred percent [1] . Even worse, these errors can be completely unpredictable, increasing or decreasing predicted drop size depending on the mesh resolution [2] .These simulation errors have two very serious consequences [3] . First, the simulation error impedes the correct evaluation of physical models. When a model predicts incorrect spray behavior, it is difficult to identify whether this is the fault of mesh or physical model. If a model gives the correct result, it is also difficult to make clear whether it will continue to function when one changes the mesh or time step. It is quite possible that researchers make bad decisions based on the results contaminated by simulation error. The second issue is that multi-dimensional computational fluid dynamics (CFD) is becoming more central to the engine design process; the importance of reliability also increases. In order to use CFD in the design process of direct injection eng...

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confidence: 98%

Algorithms for improving accuracy of spray simulation

Zhang

Xiao

et al. 2007

Chin. Sci. Bull.

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“…All submodels developed at IFP [17,19], are now integrated into IFP-C3D which has become the new submodel development platform. The integration of IFP-C3D as the 3D Combustion library of AMESim ® [26] (Advanced Modeling Environment for the Simulation of engineering systems) will allow coupling between 3D and 1D as illustrated in Figure 4.…”

Section: New Cfd Softwarementioning

confidence: 99%

Towards Even Cleaner Diesel Engines: Contribution of 3D CFD Tools

Reveille

Kleemann²,

Jay³

2006

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Vers des moteurs Diesel encore plus propres : contribution des outils de simulation 3D -Les outils de Mécanique des Fluides Numérique (MFN) sont devenus essentiels à la recherche sur les moteurs Diesel. En effet, ils permettent d'appréhender les phénomènes en jeu alors même que les procé-dés de combustion deviennent de plus en plus complexes afin de répondre à des attentes diamétralement opposées : une réglementation des émissions polluantes de plus en plus sévère et l'agrément de conduite (puissance et couple en croissance perpétuelle) qu'attend le client de son véhicule. Cependant, les outils de MFN ne peuvent être plus précis que leurs sous-modèles, raison pour laquelle la modélisation de l'injection, de l'auto inflammation et de la combustion sont en perpétuelle évolution afin d'être en adéquation avec les phénomènes rencontrés durant les essais au banc moteur. Cette adéquation permet à la simulation tridimensionnelle de contribuer activement aux divers projets de recherche sur les moteurs Diesel à l'IFP. De nouveaux modèles ont été développés pour la combustion et l'auto-inflammation basse température afin de reproduire fidèlement la combustion HCCI. Récemment, l'IFP a proposé un nouveau concept de combustion bimode à faibles émissions de NOx et suies nommé NADI TM qui passe de la combustion HCCI aux charges partielles à la combustion conventionnelle pour les fortes charges. Forte des récents développements, la MFN a fortement contribué au développement du concept NADI TM de par sa capacité à analyser les phénomènes en jeu et d'extraire des axes de progression dans les 2 modes de combustion. De plus, la MFN s'est avérée un excellent outil pour le portage du concept sur une multitude d'applications. Les simulations qui peuvent maintenant être réalisées sur une très large plage de fonctionnement moteur (jusqu'à 60 % d'EGR) permettent de concevoir et d'optimiser toutes les générations de moteurs Diesel Injection Directe pour des applications véhicules légers ou poids lourds. Les effets de paramètres tels que la géométrie du piston, le système d'injection, l'aérodynamique interne et le taux d'EGR peuvent être cartographiés afin d'en extraire la configuration qui réponde au mieux aux objectifs. Abstract -Towards even cleaner Diesel engines: Contribution of 3D CFD tools -Three-dimensional

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“…7 Abraham 8 investigated the grid dependence of the spray models for vaporising diesel sprays in a constant-volume chamber and suggested that the nozzle region must be adequately resolved to obtain an accurate prediction of the spray structure. Later, Beard et al 6,9 reported that the relative velocity between the liquid phase and the gas phase is mesh dependent and thus may result in a lower axial velocity and incorrect liquid and vapour penetration lengths by comparison of the axial velocity distribution and the liquid and vapour penetration lengths for a vaporising diesel spray when using the LDEF method. They proposed gaseous particles and a sphere of momentum influence to modify the error relative velocity.…”

Section: Introductionmentioning

confidence: 99%

“…5, 6 A previous study found that this method may cause incorrect momentum coupling between the gas phase and the liquid phase and may result in resolution-dependent results when the spatial distribution of droplets is highly non-uniform. 7 Abraham 8 investigated the grid dependence of the spray models for vaporising diesel sprays in a constant-volume chamber and suggested that the nozzle region must be adequately resolved to obtain an accurate prediction of the spray structure.…”

Section: Introductionmentioning

confidence: 99%

Effects of the turbulence model and the spray model on predictions of the n-heptane jet fuel–air mixing and the ignition characteristics with a reduced chemistry mechanism

Wei

Chen

Zhao

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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Reynolds-averaged Navier–Stokes simulations with an improved spray model and a realistic chemistry mechanism are performed for turbulent spray flames under diesel-like conditions in a constant-volume chamber. Comprehensive numerical analyses including two turbulence models (the renormalisation group k– ε model and the standard two-equation k– ε model) with different model coefficients are made. The distribution of the fuel mixture fractions is a very important factor affecting the combustion process. In this study, we also use the entrainment gas-jet model, modifications of the the spray model coefficient and two turbulence models to investigate extensively the influence of the gas-jet theory model on the fuel–air mixture process. First, a non-reacting case is validated by comparing the liquid-phase penetration and the vapour-phase penetration and also the mixture fractions at different axis positions. Second, approriate methods are confirmed according to accurate mixture fraction distributions to validate the combustion process. Because of the large number of species and reactions, the calculation of chemically reacting flows is unaffordable, particularly for three-dimensional simulations. Hence, the dynamic adaptive chemistry method for efficient chemistry calculations is extended in this work to reduce the computational cost of the spray combustion process when a reduced chemistry mechanism is used. The results show that, in the evaporation case, the gas-jet theory model can be used to obtain a relatively accurate fuel vapour penetration length with different influential factors and that improved numerical methods can effectively reduce the mesh dependence for the spray evaporation process. It is demonstrated that the Schmidt number Sc and the turbulence models significantly influence the mixture fraction distribution. Very good agreement with available experimental data is found concerning the ignition delay time and the flame lift-off length for different oxygen concentrations owing to the accurate fuel mixture fraction.

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Extension of Lagrangian-Eulerian Spray Modeling: Application to High Pressure Evaporating Diesel Sprays

Cited by 60 publications

References 23 publications

Algorithms for improving accuracy of spray simulation

Algorithms for improving accuracy of spray simulation

Towards Even Cleaner Diesel Engines: Contribution of 3D CFD Tools

Effects of the turbulence model and the spray model on predictions of the n-heptane jet fuel–air mixing and the ignition characteristics with a reduced chemistry mechanism

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