A multidimensional simulation of Auxiliary Gas Injection (AGI) for late cycle oxygen enrichment w... more A multidimensional simulation of Auxiliary Gas Injection (AGI) for late cycle oxygen enrichment was exercised to assess the merits of AGI for reducing the emissions of soot from heavy duty diesel engines while not adversely affecting the NOâ emissions of the engine. Here, AGI is the controlled enhancement of mixing within the diesel engine combustion chamber by high speed jets
ASME 2007 Internal Combustion Engine Division Fall Technical Conference, 2007
The objective of this research was to experimentally evaluate the effects of two biodiesel fuels ... more The objective of this research was to experimentally evaluate the effects of two biodiesel fuels with different viscosities on fuel injection characteristics using a light-duty, common-rail, diesel injection system. A pure biodiesel (B100) and a 50/50 blend of pure biodiesel and refined, bleached, and deodorized vegetable oil (B50V50) were compared with a laboratory diesel fuel equivalent (D100). The fuel viscosity
ASME 2007 Internal Combustion Engine Division Fall Technical Conference, 2007
ABSTRACT New U.S. Environmental Protection Agency regulations are forcing locomotive manufacturer... more ABSTRACT New U.S. Environmental Protection Agency regulations are forcing locomotive manufacturers and railroads to reduce pollutant emissions from locomotive operation. Locomotive engines will be required to meet the applicable standards at the time of original manufacture. A variety of emissions-reduction technologies can be used, such as alternative fuels, additives in lubricant oil, and aftertreatment technologies (e.g., selective catalytic reduction and particulate traps). Emissions reduction can also be accomplished inside the cylinder, using advanced diesel fuel injectors that have a significant impact on the quality of spray and charge preparation before engine combustion and subsequent events. High-speed optical measurements have been collected at elevated ambient pressures for sprays from a modular common rail injection system at Argonne National Laboratory in order to investigate spray structure and dynamics. High-speed laser imaging was used to explore the effects of various parameters on the spray structure. The experimental parameters included were ambient gas density, injection pressure, number of spray holes, injection strategy, and internal orifice size. Spray symmetry and structure were found to depend significantly on the nozzle geometry or manufacturing variances and the operating conditions.
ABSTRACT Traditional Lagrangian spray modeling approaches for internal combustion engines are hig... more ABSTRACT Traditional Lagrangian spray modeling approaches for internal combustion engines are highly grid-dependent due to insufficient resolution in the near nozzle region. This is primarily because of inherent restrictions of volume fraction with the Lagrangian assumption together with high computational costs associated with small grid sizes. A state-of-the-art grid-convergent spray modeling approach was recently developed and implemented by Senecal et al., (ASME-ICEF2012-92043) in the CONVERGE software. The key features of the methodology include Adaptive Mesh Refinement (AMR), advanced liquid-gas momentum coupling, and improved distribution of the liquid phase, which enables use of cell sizes smaller than the nozzle diameter. This modeling approach was rigorously validated against non-evaporating, evaporating, and reacting data from the literature. The current numerical study focuses on further demonstration of the grid-convergent modeling approach for simulating a single-cylinder Cat® compression ignition engine. The simulated injector is characterized with a nominal nozzle exit diameter of 259 μm. Simulations using various minimum grid sizes (ranging from 125 μm to 1000 μm) are compared for engine performance and emissions parameters of interest such as pressure, heat release rate, ignition delay, NOx, HC, and soot emissions. The peak cell-count for the highest resolution simulation was on the order of 34 million. These computationally expensive simulations were facilitated at a high-performance computing facility at Argonne National Laboratory. Scaling studies were also performed. The validity of previously recommended grid settings (ASMEICEF2012-92043) for accuracy/runtime trade-off is further assessed. Efficacy of a simplified combustion model is also compared against a detailed chemical-kinetics-based combustion model.
ABSTRACT This paper implements a coupled approach to integrate the internal nozzle flow and the e... more ABSTRACT This paper implements a coupled approach to integrate the internal nozzle flow and the ensuing fuel spray using a Volume-of-Fluid (VOF) method in the finite-volume framework. A VOF method is used to model the internal nozzle two-phase flow with a cavitation description closed by the homogeneous relaxation model of Bilicki and Kestin, 1990. An Eulerian single velocity field approach by Vallet et al., 2001 is implemented for near-nozzle spray modeling. This Eulerian approach considers the liquid and gas phases as a complex mixture with a highly variable density to describe near nozzle dense sprays. The liquid mass fraction is transported with a model for the turbulent liquid diffusion flux into the gas. Fully-coupled nozzle flow and spray simulations are performed in three dimensions and validated against the x-ray radiography measurements of Kastengren et al., 2014 for a diesel fuel surrogate. A standard Reynolds Averaged Navier Stokes based turbulence model is used in this study and the influence of model constants is evaluated. First, the grid convergence study is performed. The effect of grid size is also evaluated by comparing the fuel distribution against experimental data. Finally, the fuel distribution predicted by the coupled Eulerian approach is compared against that by Lagrangian-Eulerian spray model along with experimental data. The coupled Eulerian approach provides a unique way of coupling the nozzle flow and sprays so that the effects of in-nozzle flow can be directly realized on the fuel spray. Both experiment and numerical simulations show non-cavitation occurring for this injector with convergent nozzle geometry. The study shows that the Eulerian approach has advantages over near-field dense spray distributions.
A multidimensional simulation of Auxiliary Gas Injection (AGI) for late cycle oxygen enrichment w... more A multidimensional simulation of Auxiliary Gas Injection (AGI) for late cycle oxygen enrichment was exercised to assess the merits of AGI for reducing the emissions of soot from heavy duty diesel engines while not adversely affecting the NOâ emissions of the engine. Here, AGI is the controlled enhancement of mixing within the diesel engine combustion chamber by high speed jets
ASME 2007 Internal Combustion Engine Division Fall Technical Conference, 2007
The objective of this research was to experimentally evaluate the effects of two biodiesel fuels ... more The objective of this research was to experimentally evaluate the effects of two biodiesel fuels with different viscosities on fuel injection characteristics using a light-duty, common-rail, diesel injection system. A pure biodiesel (B100) and a 50/50 blend of pure biodiesel and refined, bleached, and deodorized vegetable oil (B50V50) were compared with a laboratory diesel fuel equivalent (D100). The fuel viscosity
ASME 2007 Internal Combustion Engine Division Fall Technical Conference, 2007
ABSTRACT New U.S. Environmental Protection Agency regulations are forcing locomotive manufacturer... more ABSTRACT New U.S. Environmental Protection Agency regulations are forcing locomotive manufacturers and railroads to reduce pollutant emissions from locomotive operation. Locomotive engines will be required to meet the applicable standards at the time of original manufacture. A variety of emissions-reduction technologies can be used, such as alternative fuels, additives in lubricant oil, and aftertreatment technologies (e.g., selective catalytic reduction and particulate traps). Emissions reduction can also be accomplished inside the cylinder, using advanced diesel fuel injectors that have a significant impact on the quality of spray and charge preparation before engine combustion and subsequent events. High-speed optical measurements have been collected at elevated ambient pressures for sprays from a modular common rail injection system at Argonne National Laboratory in order to investigate spray structure and dynamics. High-speed laser imaging was used to explore the effects of various parameters on the spray structure. The experimental parameters included were ambient gas density, injection pressure, number of spray holes, injection strategy, and internal orifice size. Spray symmetry and structure were found to depend significantly on the nozzle geometry or manufacturing variances and the operating conditions.
ABSTRACT Traditional Lagrangian spray modeling approaches for internal combustion engines are hig... more ABSTRACT Traditional Lagrangian spray modeling approaches for internal combustion engines are highly grid-dependent due to insufficient resolution in the near nozzle region. This is primarily because of inherent restrictions of volume fraction with the Lagrangian assumption together with high computational costs associated with small grid sizes. A state-of-the-art grid-convergent spray modeling approach was recently developed and implemented by Senecal et al., (ASME-ICEF2012-92043) in the CONVERGE software. The key features of the methodology include Adaptive Mesh Refinement (AMR), advanced liquid-gas momentum coupling, and improved distribution of the liquid phase, which enables use of cell sizes smaller than the nozzle diameter. This modeling approach was rigorously validated against non-evaporating, evaporating, and reacting data from the literature. The current numerical study focuses on further demonstration of the grid-convergent modeling approach for simulating a single-cylinder Cat® compression ignition engine. The simulated injector is characterized with a nominal nozzle exit diameter of 259 μm. Simulations using various minimum grid sizes (ranging from 125 μm to 1000 μm) are compared for engine performance and emissions parameters of interest such as pressure, heat release rate, ignition delay, NOx, HC, and soot emissions. The peak cell-count for the highest resolution simulation was on the order of 34 million. These computationally expensive simulations were facilitated at a high-performance computing facility at Argonne National Laboratory. Scaling studies were also performed. The validity of previously recommended grid settings (ASMEICEF2012-92043) for accuracy/runtime trade-off is further assessed. Efficacy of a simplified combustion model is also compared against a detailed chemical-kinetics-based combustion model.
ABSTRACT This paper implements a coupled approach to integrate the internal nozzle flow and the e... more ABSTRACT This paper implements a coupled approach to integrate the internal nozzle flow and the ensuing fuel spray using a Volume-of-Fluid (VOF) method in the finite-volume framework. A VOF method is used to model the internal nozzle two-phase flow with a cavitation description closed by the homogeneous relaxation model of Bilicki and Kestin, 1990. An Eulerian single velocity field approach by Vallet et al., 2001 is implemented for near-nozzle spray modeling. This Eulerian approach considers the liquid and gas phases as a complex mixture with a highly variable density to describe near nozzle dense sprays. The liquid mass fraction is transported with a model for the turbulent liquid diffusion flux into the gas. Fully-coupled nozzle flow and spray simulations are performed in three dimensions and validated against the x-ray radiography measurements of Kastengren et al., 2014 for a diesel fuel surrogate. A standard Reynolds Averaged Navier Stokes based turbulence model is used in this study and the influence of model constants is evaluated. First, the grid convergence study is performed. The effect of grid size is also evaluated by comparing the fuel distribution against experimental data. Finally, the fuel distribution predicted by the coupled Eulerian approach is compared against that by Lagrangian-Eulerian spray model along with experimental data. The coupled Eulerian approach provides a unique way of coupling the nozzle flow and sprays so that the effects of in-nozzle flow can be directly realized on the fuel spray. Both experiment and numerical simulations show non-cavitation occurring for this injector with convergent nozzle geometry. The study shows that the Eulerian approach has advantages over near-field dense spray distributions.
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