A Spherical Volume Interaction DDM Approach for Diesel Spray Modeling

Torelli, Roberto; D’Errico, Gianluca; Lucchini, Tommaso; Ikonomou, V.; McDavid, Robert M.

doi:10.1615/atomizspr.2015010623

Cited by 10 publications

(4 citation statements)

References 20 publications

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“…With reference to the standard k-ε turbulence model, it was observed that the value of the C ε1 constant heavily influences the outcome of spray simulations. For diesel sprays, which are predominantly characterized by a round jet shape of the plumes, a value greater than 1.44 allowed for more accurate results [38] by mitigating the tendency of the models to overpredict the round jets spreading rate [39]. On the other hand, the jets of GDI sprays are closer and they are thus subjected to a different flow field.…”

Section: Standard Ecn Condition: Spray Penetrationmentioning

confidence: 99%

Combined Experimental and Numerical Investigation of the ECN Spray G under Different Engine-Like Conditions

Paredi¹,

Lucchini²,

D’Errico³

et al. 2018

SAE Technical Paper Series

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A detailed understanding of Gasoline Direct Injection (GDI) techniques applied to spark-ignition (SI) engines is necessary as they allow for many technical advantages such as increased power output, higher fuel efficiency and better cold start performances. Within this context, the extensive validation of multi-dimensional models against experimental data is a fundamental task in order to achieve an accurate reproduction of the physical phenomena characterizing the injected fuel spray. In this work, simulations of different Engine Combustion Network (ECN) Spray G conditions were performed with the Lib-ICE code, which is based on the open source OpenFOAM technology, by using a RANS Eulerian-Lagrangian approach to model the ambient gas-fuel spray interaction. Foremost, the main scope of the activity was to identify the most accurate numerical setup in terms of atomization ad secondary break-up models, thanks to a validation of the computed results against experimental data available for the ECN Spray G baseline condition. Specifically, attention was focused on spray penetration along with an analysis of spray morphology and effects of plume-to-plume interaction. Afterwards, the reference setup was tested and validated under different operating conditions, characterized by detailed experimental measurements specifically provided for this work. In particular, Mie scattering and Schlieren techniques allowed the quasi-simultaneous acquisition of both vapor and liquid penetrations, while a customized imageprocessing procedure, developed in Matlab environment, was used for the outline of the spray contours of both fuel phases to measure the parameters characterizing the jet development. A robust reference numerical setup was identified, capable to reproduce with good accuracy the injection process of a multi-hole GDI spray under the wide range of tested operating conditions. COMBINED EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THE ECN SPRAY G

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Section: Standard Ecn Condition: Spray Penetrationmentioning

confidence: 99%

Combined Experimental and Numerical Investigation of the ECN Spray G under Different Engine-Like Conditions

Paredi¹,

Lucchini²,

D’Errico³

et al. 2018

SAE Technical Paper Series

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“…Pope (Pope, 1978) stated in his work, that by using the higher value of C ε1 may yield better results as a round jet correction. For a diesel spray, which is approximated as round jets, when an increase in C ε1 values resulted in better agreement with the experimental data (Torelli et al, 2015). It is important to note here, C ε1 1.44 seems sufficient to get reasonable agreement for liquid and vapor penetrations.…”

Section: Model Validation With Ecn Datamentioning

confidence: 73%

On Modeling of Spray G ECN Using ROI-Based Eulerian-Lagrangian Simulation

Ailaboina

Saha

2022

Front. Mech. Eng.

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A numerical study has been carried out to understand the effects of Unsteady Reynolds Averaged Navier-Stokes (standard k ― ε and RNG k ― ε model) and large eddy simulations (LES) on a multi-hole gasoline direct injection (GDI) system. The fuel injector considered in this study is the Spray G nozzle from the Engine Combustion Network (ECN). A blob injection model, based on empirical rate of injection (ROI) profile, is considered in this study. The latest data on spray penetrations from Engine Combustion Network is used for model validation along with experimental findings on suction velocity and local droplet diameter. The spray breakup is simulated by using the KH-RT breakup length model. The turbulence model constant Cε1, is tuned to match with the experimental data of liquid and vapor penetrations in simulations while using the standard k-ε turbulence model. On the other hand, the Kelvin-Helmholtz breakup model time constant (B1) and Rayleigh Taylor breakup length constant (Cbl) are tuned for the RNG k ― ε turbulence model. From this work it is observed that by increasing the breakup length model constants (Cbl), the radial dispersion of the spray increases, and the extent of breakup is lowered. The set of optimized model parameters used with RNG k - ε is also used for LES modeling studies with different sub-grid models. The spray penetrations with standard k ― ε turbulence (Cε1=1.44) model are reported underpredicting, and the RNG k ― ε and LES sub-grid models predicted well with the latest and recommended data from ECN. In terms of gas axial velocity comparison, the standard k-ε(Cε1=1.44) simulation setup does not perform as well as the simulation setups using RNG k-ε and LES turbulence models (with breakup parameters: Cbl = 16 and B1 = 32). However, the standard k-ε(Cε1=1.44) simulation setup perform better than the simulation setups using RNG k-ε and LES turbulence models (with breakup parameters: Cbl = 16 and B1 = 32) when it comes to predicting local droplet diameter at 15 mm downstream of the injector tip. A parametric study is also performed considering the geometry of the stepped holes in the computational domain. The rate of injection based simulation is initiated at the end of the smaller hole. The case including the stepped holes led to over-prediction compared to the case with the usual computational domain (i.e., without the stepped holes), in terms of spray penetrations, but exhibited higher levels of fluctuations in the spray morphology. Finally, parametric studies were carried out to understand the relative importance of the individual spray sub-models (breakup, evaporation and collision) and the results are conclusive that for a spray simulation the breakup models are the dominant factors.

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“…It is noted that the KH-RT model is meant to describe the mechanical and aerodynamic instabilities of liquid jets, and, in principle, cannot represent the flash-boiling-induced atomization mechanism. Nevertheless, this breakup model (as well as the other spray submodels mentioned above) is commonly and widely used to model spray breakup in ICE applications under many conditions, [39][40][41][42] often without recognizing its applicability limits. Hence, one of the goals of this study is to assess the KH-RT model performance when dealing with flash boiling sprays.…”

Section: Modeling Approachmentioning

confidence: 99%

In-cylinder spray evolution in a motored central-injection gasoline engine: Imaging and simulating the effects of flash-boiling and intake crossflow

Guo,

Torelli,

Kim

et al. 2024

International Journal of Engine Research

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Accurate predictions of fuel spray behavior and mixture formation in simulations of direct-injection spark-ignition (DISI) engines are fundamental to ensure proper description of all subsequent processes including ignition, combustion, and emissions. In this work, the spray evolution in a single-cylinder optical DISI engine was studied experimentally and numerically with the goal of enabling predictive computational fluid dynamics (CFD) modeling of in-cylinder sprays. The authors explored a wide range of operating conditions characterized by several fuel injection temperatures and engine speeds, using a well-characterized nine-component gasoline surrogate known as PACE-20. The effect of flash boiling and intake crossflow on the spray is discussed, with a focus on evaluating the ability of the spray models to capture highly transient spray behavior. In the experiments, the fuel temperature was varied between 20°C and 80°C, allowing for non-flash- to flash-boiling transition to emerge with enhanced flashing intensity at the highest temperatures. Spray collapse resulted in vapor-rich regions, owing to the locally lower inertia of the fluid. Varying the engine speed from 650 to 1950 rpm promoted increasingly more turbulent in-cylinder crossflow which interacted with the spray during the injection event and resulted in enhanced spray dispersion. The CFD model was able to capture the spray morphology transition at different fuel temperatures and engine speeds adequately. It is shown that the spray breakup model could capture the transitional spray behavior induced by flash boiling atomization and intake flow via proper initialization of the spray cone angle and calibration of the spray models’ constants.

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A Spherical Volume Interaction DDM Approach for Diesel Spray Modeling

Abstract: This work presents an implementation and evaluation of an alternative approach for describing exchange of mass, momentum and energy in Diesel spray CFD simulations using Discrete Droplet Modeling (DDM

Cited by 10 publications

References 20 publications

Combined Experimental and Numerical Investigation of the ECN Spray G under Different Engine-Like Conditions

Combined Experimental and Numerical Investigation of the ECN Spray G under Different Engine-Like Conditions

On Modeling of Spray G ECN Using ROI-Based Eulerian-Lagrangian Simulation

In-cylinder spray evolution in a motored central-injection gasoline engine: Imaging and simulating the effects of flash-boiling and intake crossflow

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