Grid-Convergent Spray Models for Internal Combustion Engine CFD Simulations

2012 ◽  
Author(s):  
P. K. Senecal ◽  
E. Pomraning ◽  
K. J. Richards ◽  
S. Som
Keyword(s):  
Liquid Phase ◽  
Adaptive Mesh Refinement ◽  
State Of The Art ◽  
Combustion Engine ◽  
Adaptive Mesh ◽  
Cfd Simulations ◽  
Modeling Methodology ◽  
Grid Convergence ◽  
Key Features ◽  
Momentum Coupling

A state-of-the-art spray modeling methodology is presented. Key features of the methodology, such as Adaptive Mesh Refinement (AMR), advanced liquid-gas momentum coupling, and improved distribution of the liquid phase, are described. The ability of this approach to use cell sizes much smaller than the nozzle diameter is demonstrated. Grid convergence of key parameters is verified for non-evaporating, evaporating, and reacting spray cases using cell sizes down to 1/32 mm. Grid settings are recommended that optimize the accuracy/runtime tradeoff for RANS-based spray simulations.

Grid-Convergent Spray Models for Internal Combustion Engine Computational Fluid Dynamics Simulations

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
P. K. Senecal ◽  
E. Pomraning ◽  
K. J. Richards ◽  
S. Som
Keyword(s):  
Adaptive Mesh Refinement ◽  
State Of The Art ◽  
Combustion Engine ◽  
Adaptive Mesh ◽  
Modeling Methodology ◽  
Grid Convergence ◽  
Computational Fluid Dynamics Simulations ◽  
Key Features ◽  
Dynamics Simulations ◽  
Momentum Coupling

A state-of-the-art spray modeling methodology is presented. Key features of the methodology, such as adaptive mesh refinement (AMR), advanced liquid–gas momentum coupling, and improved distribution of the liquid phase, are described. The ability of this approach to use cell sizes much smaller than the nozzle diameter is demonstrated. Grid convergence of key parameters is verified for nonevaporating, evaporating, and reacting spray cases using cell sizes down to 1/32 mm. Grid settings are recommended that optimize the accuracy/runtime tradeoff for RANS-based spray simulations.

Large Eddy Simulation of Vaporizing Sprays Considering Multi-Injection Averaging and Grid-Convergent Mesh Resolution

2013 ◽  
Author(s):  
P. K. Senecal ◽  
E. Pomraning ◽  
Q. Xue ◽  
S. Som ◽  
S. Banerjee ◽  
...  
Keyword(s):  
Adaptive Mesh Refinement ◽  
Mixture Fraction ◽  
Adaptive Mesh ◽  
Dynamic Structure ◽  
Ensemble Averaging ◽  
Eddy Simulation ◽  
Modeling Methodology ◽  
Large Eddy ◽  
Minimum Number ◽  
Les Model

A state-of-the-art spray modeling methodology, recently presented by Senecal et al. [1, 2], is applied to Large Eddy Simulations (LES) of vaporizing sprays. Simulations of non-combusting Spray A (n-dodecane fuel) from the Engine Combustion Network are performed. An Adaptive Mesh Refinement (AMR) cell size of 0.0625 mm is utilized based on the accuracy/runtime tradeoff demonstrated by Senecal et al. [2]. In that work it was shown that grid convergence of key parameters for non-evaporating and evaporating sprays was achieved for cell sizes between 0.0625 and 0.125 mm using the Dynamic Structure LES model. The current work presents an extended and more thorough investigation of Spray A using multi-dimensional spray modeling and the Dynamic Structure LES model. Twenty different realizations are simulated by changing the random number seed used in the spray sub-models. Multi-realization (ensemble) averaging is shown to be necessary when comparing to local spray measurements of quantities such as mixture fraction and gas-phase velocity. Through a detailed analysis, recommendations are made regarding the minimum number of LES realizations required for accurate prediction of Diesel sprays. Finally, the effect of a spray primary breakup model constant on the results is assessed.

The NEMO (Nucleus for European Modelling of the Ocean) numerical ocean platform

2020 ◽  
Author(s):  
Guillaume Samson ◽  
Claire Levy ◽  
Nemo System Team
Keyword(s):  
Adaptive Mesh Refinement ◽  
State Of The Art ◽  
Adaptive Mesh ◽  
Ocean Model ◽  
Ocean Dynamics ◽  
Ice Shelves ◽  
Model Code ◽  
Set Up ◽  
Climate Studies

<p>The Nucleus for European Modelling of the Ocean (NEMO) is a state-of-the art modelling platform for oceanographic research, operational oceanography, sesonnal forecasts and climate studies. NEMO includes three major components; the blue ocean (dynamics), the white ocean (sea-ice), the green ocean (ocean biogeochemistry). It also allows coupling through interfaces with atmosphere (through OASIS software), waves, ice-shelves, so as nesting through the adaptive mesh refinement software AGRIF. Some reference configurations and test cases allowing to explore, to set-up and to validate the applications, and a set of tools to use the platform are also available to the community. The whole platform and its documentation are available under free licence.</p><p>The evolution and reliability of NEMO are organised and controlled by a European Consortium between CMCC (Italy), CNRS (France), MOI France), NOC (UK), UKMO (UK).</p><p>Consortium members agree on long term strategy and yearly plans, sharing expertise and efforts within the NEMO System Team: the core team of NEMO developers in order to ensure the successful and sustainable development of the NEMO System as a well-organised, state-of-the-art ocean model code system suitable for both research and operational work</p>

Large Eddy Simulation of Vaporizing Sprays Considering Multi-Injection Averaging and Grid-Convergent Mesh Resolution

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
P. K. Senecal ◽  
E. Pomraning ◽  
Q. Xue ◽  
S. Som ◽  
S. Banerjee ◽  
...  
Keyword(s):  
Internal Combustion Engine ◽  
Turbulence Model ◽  
Adaptive Mesh Refinement ◽  
Combustion Engine ◽  
Mixture Fraction ◽  
Dynamic Structure ◽  
Internal Combustion ◽  
Grid Convergence ◽  
Large Eddy ◽  
Les Model

A state-of-the-art spray modeling methodology, recently presented by Senecal et al. (2012, “Grid Convergent Spray Models for Internal Combustion Engine CFD Simulations,” Proceedings of the ASME 2012 Internal Combustion Engine Division Fall Technical Conference, Vancouver, Canada, Paper No. ICEF2012-92043; 2013 “An Investigation of Grid Convergence for Spray Simulations using an LES Turbulence Model,” Paper No. SAE 2013-01-1083) is applied to large eddy simulations (LES) of vaporizing sprays. Simulations of noncombusting Spray A (n-dodecane fuel) from the engine combustion network are performed. An adaptive mesh refinement (AMR) cell size of 0.0625 mm is utilized based on the accuracy/runtime tradeoff demonstrated by Senecal et al. (2013, “An Investigation of Grid Convergence for Spray Simulations using an LES Turbulence Model,” Paper No. SAE 2013-01-1083). In that work, it was shown that grid convergence of key parameters for nonevaporating and evaporating sprays was achieved for cell sizes between 0.0625 and 0.125 mm using the dynamic structure LES model. The current work presents an extended and more thorough investigation of Spray A using multidimensional spray modeling and the dynamic structure LES model. Twenty different realizations are simulated by changing the random number seed used in the spray submodels. Multirealization (ensemble) averaging is shown to be necessary when comparing to local spray measurements of quantities such as mixture fraction and gas-phase velocity. Through a detailed analysis, recommendations are made regarding the minimum number of LES realizations required for accurate prediction of diesel sprays. Finally, the effect of a spray primary breakup model constant on the results is assessed.

LES of Vaporizing Gasoline Sprays Considering Multi-Injection Averaging and Grid-Convergent Mesh Resolution

2015 ◽  
Author(s):  
S. Som ◽  
Z. Wang ◽  
Y. Pei ◽  
P. K. Senecal ◽  
E. Pomraning
Keyword(s):  
Adaptive Mesh Refinement ◽  
Direct Injection ◽  
Injection Pressure ◽  
Adaptive Mesh ◽  
Dynamic Structure ◽  
Gasoline Direct Injection ◽  
Modeling Methodology ◽  
Mesh Resolution ◽  
Minimum Number ◽  
Les Model

A state-of-the-art spray modeling methodology, recently presented by Senecal et al. [1,2,3], is applied to Large Eddy Simulations (LES) of vaporizing gasoline sprays. Simulations of non-combusting Spray G (gasoline fuel) from the Engine Combustion Network are performed. Adaptive mesh refinement (AMR) with cell sizes from 0.09 mm to 0.5 mm are utilized to demonstrate grid convergence of the dynamic structure LES model for the gasoline sprays. Grid settings are recommended to optimize the accuracy/runtime tradeoff for LES-based spray simulations at different injection pressure conditions typically encountered in gasoline direct injection (GDI) applications. Twenty different realizations are simulated by changing the random number seed used in the spray sub-models. It is shown that for global quantities such as spray penetration, comparing a single LES simulation to experimental data is reasonable. Through a detailed analysis using the relevance index (RI) criteria, recommendations are made regarding the minimum number of LES realizations required for accurate prediction of the gasoline sprays.

scholarly journals Predictions of Transient Flame Lift-off Length With Comparison to Single-Cylinder Optical Engine Experiments

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
P. K. Senecal ◽  
E. Pomraning ◽  
J. W. Anders ◽  
M. R. Weber ◽  
C. R. Gehrke ◽  
...  
Keyword(s):  
Cell Size ◽  
Adaptive Mesh Refinement ◽  
Combustion Engine ◽  
Adaptive Mesh ◽  
Cylinder Pressure ◽  
Simulation Methodology ◽  
Single Cylinder ◽  
Optical Engine ◽  
Mesh Resolution ◽  
Lift Off

A state-of-the-art, grid-convergent simulation methodology was applied to three-dimensional calculations of a single-cylinder optical engine. A mesh resolution study on a sector-based version of the engine geometry further verified the RANS-based cell size recommendations previously presented by Senecal et al. (“Grid Convergent Spray Models for Internal Combustion Engine CFD Simulations,” ASME Paper No. ICEF2012-92043). Convergence of cylinder pressure, flame lift-off length, and emissions was achieved for an adaptive mesh refinement cell size of 0.35 mm. Full geometry simulations, using mesh settings derived from the grid convergence study, resulted in excellent agreement with measurements of cylinder pressure, heat release rate, and NOx emissions. On the other hand, the full geometry simulations indicated that the flame lift-off length is not converged at 0.35 mm for jets not aligned with the computational mesh. Further simulations suggested that the flame lift-off lengths for both the nonaligned and aligned jets appear to be converged at 0.175 mm. With this increased mesh resolution, both the trends and magnitudes in flame lift-off length were well predicted with the current simulation methodology. Good agreement between the overall predicted flame behavior and the available chemiluminescence measurements was also achieved. The present study indicates that cell size requirements for accurate prediction of full geometry flame lift-off lengths may be stricter than those for global combustion behavior. This may be important when accurate soot predictions are required.

Modeling Fuel Spray Vapor Distribution With Large Eddy Simulation of Multiple Realizations

2014 ◽  
Author(s):  
P. K. Senecal ◽  
S. Mitra ◽  
E. Pomraning ◽  
Q. Xue ◽  
S. Som ◽  
...  
Keyword(s):  
Adaptive Mesh Refinement ◽  
Current Model ◽  
Mixture Fraction ◽  
Adaptive Mesh ◽  
Dynamic Structure ◽  
Ensemble Averaging ◽  
Eddy Simulation ◽  
Modeling Methodology ◽  
Large Eddy ◽  
Les Model

A state-of-the-art spray modeling methodology, recently presented by Senecal et al. [1, 2, 3], is applied to Large Eddy Simulations (LES) of vaporizing sprays. Simulations of non-combusting Spray H (n-heptane fuel) from the Engine Combustion Network are performed. Adaptive Mesh Refinement (AMR) cell sizes of 0.03125 mm to 0.25 mm are utilized to further demonstrate grid convergence of the Dynamic Structure LES model for diesel sprays. Twenty-eight different realizations are simulated by changing the random number seed used in the spray submodels. Multi-realization (ensemble) averaging, which has been shown to be necessary when comparing to local spray measurements, is performed. Global quantities such as liquid and vapor penetration are compared, as well as local mean mixture fraction and mixture fraction standard deviation. The results suggest that the current model does a reasonable job predicting the major features of the n-heptane spray when appropriate grid resolution is utilized.

Employing Adaptive Mesh Refinement for Simulating the Exhaust Gas Recirculation Mixing Process

2014 ◽  
Author(s):  
Richard Bramlette ◽  
Chenaniah Langness ◽  
Michael Mangus ◽  
Christopher Depcik
Keyword(s):  
Adaptive Mesh Refinement ◽  
Combustion Engine ◽  
Three Dimensional ◽  
Adaptive Mesh ◽  
Exhaust Gas Recirculation ◽  
Computational Time ◽  
No Production ◽  
Exhaust Gas ◽  
Single Cylinder ◽  
Gas Recirculation

One significant emissions issue of compression ignition engines that directly influences human health is the production of nitrogen oxides (NOx). Once produced, these species are difficult to convert catalytically in the exhaust and often require a complex aftertreatment system to mitigate their release into the environment. The common methodology by the internal combustion engine community to reduce the amount of NOx is to employ Exhaust Gas Recirculation (EGR) in order to dilute the intake mixture with inert species (e.g., water). This lowers the combustion temperature lessening the thermal NO production mechanism. Improper mixing of EGR with the intake (species in-homogeneity, low levels of mixing turbulence, etc.) can lead to significant cylinder-to-cylinder variation in combustion temperatures and NOx emissions, making it more difficult to achieve regulatory standards. In this effort, a three-dimensional (3-D), transient, computational fluid dynamics (CFD) analysis was performed in order to more accurately model the mixing of EGR and intake for a single-cylinder test engine. Mixing is achieved for this engine by using a small rectangular box in which clean air and engine exhaust for controlled recirculation are mixed prior to engine intake. A matrix of computational analyses at different engine loads, and simulation types (large eddy and Reynolds-averaged Navier-Stokes) at 25% EGR were performed to check computational time and agreement with experimental measurements. Moreover, this effort employs the use of adaptive mesh techniques in order to understand their usage and validate correct implementation for later endeavors including more complex geometries, such as the manifold of a multi-cylinder engine. The simulation results indicate that mass flow rate and temperature of the mixture as it leaves the mixing box agree to within 3% of experimental values. Furthermore, pressures at the air and EGR inlet boundaries showed agreement to around 1% and 12%, respectively, with the experimental measuring points indicated as the reason for the difference. In addition, species mixing of carbon monoxide was uniform to within 440 ppm. Finally, the use of the models may also account for a prior discrepancy in the output power of the single-cylinder engine test stand.

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