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The Influence of Diesel End-of-Injection Rate Shape on Combustion Recession

SAE International Journal of Engines

Caterpillar, Inc.-Chad Koci, Glen Martin, Tim Bazyn, Wayne Morrison, Kenth Svensson, Christopher Gehrke
  • Journal Article
  • 2015-01-0795
Published 2015-04-14 by SAE International in United States
The effect of the shape of the EOI was investigated through a pressure-modulated injection system in order to improve the understanding of the last portion of the traditional diesel diffusion combustion process. Here, the combustion recession at EOI is when the combustion of a mixing controlled diesel jet recedes backwards toward the fuel injector nozzle orifice.Combustion recession was observed using combustion luminosity imaging filtered at 309 nm to capture OH* chemiluminescence and 430 nm to capture CH* chemiluminescence, although soot Natural Luminosity (NL) will also be visible in these measurements. Experimental spray vessel results show that for relatively slow EOI decelerations below 1 ×106 to 2 ×106 m/s2, combustion strongly recesses completely back to the nozzle in both OH* and CH*/NL imaging. 1-D jet mixing calculations add support that this strong recession is indeed fuel rich. Ambient temperature (860 to 915K range) and dilution (18.5 to 20.9% O2 range) influence the weaker combustion recession, mainly for OH* chemiluminescence imaging. The influence of temperature variation is stronger than the influence of dilution variation over the present…
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Combustion Modeling of Conventional Diesel-type and HCCI-type Diesel Combustion with Large Eddy Simulations

Caterpillar, Inc.-Tushar A. Shethaji
Engine Research Center, University of Wisconsin, Madison-Bing Hu, Christopher J. Rutland
Published 2008-04-14 by SAE International in United States
A general combustion model, in the context of large eddy simulations, was developed to simulate the full range of combustion in conventional diesel-type and HCCI-type diesels. The combustion model consisted of a Chemkin sub-model and an Extended Flamelet Time Scale (EFTS) sub-model. Specifically, Chemkin was used to simulate auto-ignition process. In the post-ignition phase, the combustion model was switched to EFTS. In the EFTS sub-model, combustion was assumed to be a combination of two elementary combustion modes: homogeneous combustion and flamelet combustion. The combustion index acted as a weighting factor blending the contributions from these two modes. The Chemkin sub-model neglected the subgrid scale turbulence-chemistry interactions whereas the EFTS model took them into account through a presumed PDF approach. The model was used to simulate an early injection mode of a Cummins DI diesel engine and a mode of a Caterpillar DI diesel engine. These engine modes are representatives of HCCI-type and conventional diesel-type combustion, respectively. The comparison with experiments shows that the model can predict both types of diesel combustion without the need of…
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Development and Validation of an Acoustic Encapsulation to Reduce Diesel Engine Noise

Caterpillar, Inc.-Joseph R. Derk
Michigan Technological University-Subhro S. Nathak, Mohan D. Rao
Published 2007-05-15 by SAE International in United States
This paper describes a study to demonstrate the feasibility of developing an acoustic encapsulation to reduce airborne noise from a commercial diesel engine. First, the various sources of noise from the engine were identified using Nearfield Acoustical Holography (NAH). Detailed NAH measurements were conducted on the four sides of the engine in an engine test cell. The main sources of noise from the engine were ranked and identified within the frequency ranges of interest. Experimental modal analysis was conducted on the oil pan and front cover plate of the engine to reveal correlations of structural vibration results with the data from the NAH.The second phase of the study involved the design and fabrication of the acoustical encapsulation (noise covers) for the engine in a test cell to satisfy the requirements of space, cost and performance constraints. The acoustical materials for the enclosure were selected to meet the frequency and temperature ranges of interest. The “noise covers” were designed to reduce the airborne sound power level from the engine by 2-5 dB in the frequency range…
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Source Identification Using an Inverse Visible Element Rayleigh Integral Approach

Caterpillar, Inc.-J. Shi
Trane, a Division of American Standard, Inc.-F. Martinus
Published 2007-05-15 by SAE International in United States
This paper documents an inverse visible element Rayleigh integral (VERI) approach. The VERI is a fast though approximate method for predicting sound radiation that can be used in the place of the boundary element method. This paper extends the method by applying it to the inverse problem where the VERI is used to generate the acoustic transfer matrix relating the velocity on the surface to measurement points. Given measured pressures, the inverse VERI can be used to reconstruct the vibration of a radiating surface. Results from an engine cover and diesel engine indicate that the method can be used to reliably quantify the sound power and also approximate directivity.
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A New Parallel Cut-Cell Cartesian CFD Code for Rapid Grid Generation Applied to In-Cylinder Diesel Engine Simulations

Caterpillar, Inc.-R. M. McDavid, M. A. Patterson, S. Hou, T. Shethaji
Convergent Thinking, LLC-P. K. Senecal, K. J. Richards, E. Pomraning, T. Yang, M. Z. Dai
Published 2007-04-16 by SAE International in United States
A new Computational Fluid Dynamics (CFD) code has been developed in order to overcome the deficiencies of traditional grid generation and mesh motion methods. The new code uses a modified cut-cell Cartesian technique that eliminates the need for the computational grid to coincide with the geometry of interest. The code also includes state-of-the-art numerical techniques and sub-models for simulating the complex physical and chemical processes that occur in engines. Features such as shared and distributed memory parallelization, a multigrid pressure solver and user-specified grid embedding allow for efficient simulations while maintaining the grid resolution necessary for accurate engine modeling. In addition, a new Adaptive Grid Embedding (AGE) technique has been developed and implemented. Sub-models for turbulence, spray injection, spray breakup, liquid drop dynamics, ignition, combustion and emissions are also included in the code. Further, a modified version of the commonly used KH-RT breakup model has been developed which incorporates viscosity effects in the Rayleigh-Taylor instability mechanism and removes the ad hoc breakup length concept.The current work presents validation of the new modeling methodology over a…
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Hydrocarbon Selective Catalytic Reduction Using a Silver-Alumina Catalyst with Light Alcohols and Other Reductants

Caterpillar, Inc.-Paul W. Park
Oak Ridge National Laboratory-John F. Thomas, Samuel A. Lewis, Bruce G. Bunting, John M. Storey, Ron L. Graves
Published 2005-04-11 by SAE International in United States
Previously reported work with a full-scale ethanol-SCR system featuring a Ag-Al2O3 catalyst demonstrated that this particular system has potential to reduce NOx emissions 80-90% for engine operating conditions that allow catalyst temperatures above 340°C. A concept explored was utilization of a fuel-borne reductant, in this case ethanol “stripped” from an ethanol-diesel micro-emulsion fuel. Increased tailpipe-out emissions of hydrocarbons, acetaldehyde and ammonia were measured, but very little N2O was detected. In the current increment of work, a number of light alcohols and other hydrocarbons were used in experiments to map their performance with the same Ag-Al2O3 catalyst. These exploratory tests are aimed at identification of compounds or organic functional groups that could be candidates for fuel-borne reductants in a compression ignition fuel, or could be produced by some workable method of fuel reforming. A second important goal was to improve understanding of the possible reaction mechanisms and other phenomena that influence performance of this SCR system. Test results revealed that diesel engine exhaust NOx emissions can be reduced by more than 80%, utilizing ethanol as the…
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An Investigation of Particulate Morphology, Microstructures, and Fractal Geometry for ael Diesel Engine-Simulating Combustor

Caterpillar, Inc.-Alexander Panov, Jill Akers, Craig Habeger
Argonne National Laboratory-Jinyu Zhu, Kyeong Lee
Published 2004-10-25 by SAE International in United States
The particulate matter (PM) produced from a diesel engine-simulating combustor was characterized in its morphology, microstructure, and fractal geometry by using a unique thermophoretic sampling and Transmission Electron Microscopy (TEM) system. These results revealed that diesel PM produced from the laboratory-scale burner showed similar morphological characteristics to the particulates produced from diesel engines. The flame air/fuel ratio and the particulate temperature history have significant influences on both particle size and fractal geometry. The primary particle sizes were measured to be 14.7 nm and 14.8 nm under stoichiometric and fuel-rich flame conditions, respectively. These primary particle sizes are smaller than those produced from diesel engines. The radii of gyration for the aggregate particles were 83.8 nm and 47.5 nm under these two flame conditions. These results were compared with particulate mobility diameters measured by using a Scanning Mobility Particle Sizer (SMPS). Fractal dimensions were also measured to standardize the geometry of the particulates collected from both diesel engines and the combustor. The result for combustor soot showed that the fractal geometry of particulates formed at a…
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Caterpillar Automatic Code Generation

Caterpillar, Inc.-Jeffrey M. Thate, Larry E. Kendrick
The MathWorks, Inc.-Siva Nadarajah
Published 2004-03-08 by SAE International in United States
Automatic code generation from models is actively used at Caterpillar for powertrain and machine control development. This technology was needed to satisfy the industry's demands for both increased software feature content, and its added complexity, and a short turn-around time. A pilot development effort was employed initially to roll out this new technology and shape the deployment strategy. As a result of a series of successful projects involving rapid prototyping and production code generation, Caterpillar will deploy MathWorks modeling and code generation products as their department-wide production development capability.The data collected indicated a reduction of person hours by a factor of 2 to 4 depending on the project and a reduction of calendar time by a factor of greater than 2.This paper discusses the challenges, results, and lessons learned, during this pilot effort from the perspectives of both Caterpillar and The MathWorks.
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Selective Catalytic Reduction of NOx Emissions from a 5.9 Liter Diesel Engine Using Ethanol as a Reductant

Caterpillar, Inc.-Alexander Panov, Paul Park
Oak Ridge National Laboratory-Michael D. Kass, John F. Thomas, Samuel A. Lewis, John M. Storey, Norberto Domingo, Ron L. Graves
Published 2003-10-27 by SAE International in United States
NOx emissions from a heavy-duty diesel engine were reduced by more than 90% and 80% utilizing a full-scale ethanol-SCR system for space velocities of 21000/h and 57000/h respectively. These results were achieved for catalyst temperatures between 360 and 400°C and for C1:NOx ratios of 4-6. The SCR process appears to rapidly convert ethanol to acetaldehyde, which subsequently slipped past the catalyst at appreciable levels at a space velocity of 57000/h. Ammonia and N2O were produced during conversion; the concentrations of each were higher for the low space velocity condition. However, the concentration of N2O did not exceed 10 ppm. In contrast to other catalyst technologies, NOx reduction appeared to be enhanced by initial catalyst aging, with the presumed mechanism being sulfate accumulation within the catalyst. A concept for utilizing ethanol (distilled from an E-diesel fuel) as the SCR reductant was demonstrated.
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Multi-Dimensional Modeling of Direct-Injection Diesel Spray Liquid Length and Flame Lift-off Length using CFD and Parallel Detailed Chemistry

Caterpillar, Inc.-T. E. Briggs, C. Y. Choi, R. M. McDavid, M. A. Patterson
Convergent Thinking, LLC-P. K. Senecal, E. Pomraning, K. J. Richards
Published 2003-03-03 by SAE International in United States
Recent measurements by Siebers et al. have shown that the flame of a high pressure Diesel spray stabilizes under quiescent conditions at a location downstream of the fuel injector. The effects of various ambient and injection parameters on the flame “lift-off” length have been investigated under typical Diesel conditions in a constant-volume combustion vessel. In the present study, the experiments of Siebers et al. have been modeled using a modified version of the KIVA-3V engine simulation code. Fuel injection and spray breakup are modeled using the KH-RT model that accounts for liquid surface instabilities due to the Kelvin-Helmholtz and Rayleigh-Taylor mechanisms. Combustion is simulated using Convergent Thinking's recently developed detailed transient chemistry solver (SAGE) that allows for any number of chemical species and reactions to be modeled. While detailed chemistry is believed to be an accurate methodology for modeling Diesel combustion, in the past the extensive run times rendered it impractical. To expedite the calculations, SAGE has been implemented into KIVA using the Message-Passing Interface (MPI). This implementation allows for the chemical reactions to be…
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