This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Visualization and Modeling of Pilot Injection and Combustion in Diesel Engines
Annotation ability available
Sector:
Language:
English
Abstract
An endoscope-based image acquisition-and-processing camera system was used for diagnostics of pilot injection combustion in a single-cylinder heavy duty diesel engine. A study of the pilot injection or light load is of interest because the spray breakup, mixing and vaporization processes are less influenced by heat feedback from the flame than in full injection cases. This allows the spray process to be decoupled from the combustion process. The experimental cases were modeled using a version of the KIVA-II code that includes improvements in the turbulence, wall heat transfer, spray, ignition and combustion models. Pilot injections of three different amounts (10, 15 and 20% of the fuel injected at 75% load and 1600 RPM) at different start-of-injection timings were studied. The imaging system included an endoscope, an intensified CID camera, a frame grabber and the control circuitry. The combustion of the pilot injections was characterized by ignition sites located below the point where the spray impinges on the piston bowl surface for the injector configuration used in this study. Multiple ignition sites were observed and the majority of the combustion occurred at the, bottom of the piston bowl, spreading along the bowl edge. As the start-of-injection timing was retarded some evidence of ignition above the impingement point was observed. However, these ignition sites did not develop into major combustion zones. Comparisons of the experimental results, which included pressure traces, heat release rates and the luminous flame images, and the numerical computations were made to assess the performance of current models in the KIVA-II code. Good agreement was obtained for the timing and location of ignition. The penetration of the flame observed in the luminous flame images was also captured in the predictions. A feature of the pilot injection that was not captured by the prediction is the spread of the flame along the edge of the piston bowl. The comparisons indicate that recent improvements in KIVA-II allow better prediction of the combustion of pilot injections.
Recommended Content
Technical Paper | Spray Combustion in Diesel Engines |
Technical Paper | Combustion and Heat Transfer Studies in a Direct-Injection Diesel Engine |
Technical Paper | Multidimensional Computation of Multicomponent Spray Vaporization and Combustion |
Authors
Citation
Ricart, L. and Reitz, R., "Visualization and Modeling of Pilot Injection and Combustion in Diesel Engines," SAE Technical Paper 960833, 1996, https://doi.org/10.4271/960833.Also In
References
- Espey. C. Dec, J. E. “Diesel Engine Combustion Studies in a Newly Designed Optical Engine Using High-speed Visualization and 2-D Laser Imaging” SAE Paper 930971 1993
- Edwards, C. F. Siebers, D. L. Hoskin, D. H. “A Study of the Autoignition Process of a Diesel Spray via High Speed Visualization” SAE Paper 920108 1992
- Kong, S.-C. “Diesel Ignition and Combustion Modeling with Comparison to In-Cylinder Flame Imaging” Mechanical Engineering Department, University of Wisconsin-Madison 1994
- Kong, S.-C. Ricart, L. M. Reitz, R. D. “In-Cylinder Flame Imaging Compared with Numerical Computations,” SAE Paper 950455 1995
- Amsden, A. A. O'Rourke, P. J. Butler, T. D. “KIVA-II - A Computer Program for Chemically Reactive Flows with Sprays” Los Alamos National Labs. 1989
- Tow, T “The Effect of Multiple Pulse Injection, Injection Rate and Injection Pressure on Particulate and NOx Emissions From a D. I. Diesel Engine,” Mechanical Engineering Department, University of Wisconsin-Madison 1994
- Ricart, L. M. “The Effects of Heat Transfer and Mixing on Diesel ignition and combustion,” Mechanical Engineering Department, university of Wisconsin-Madison 1995
- Shakal, J. A. “Effects of Auxiliary Injection on Diesel Engine Combustion,” Mechanical Engineering Department, University of Wisconsin-Madison 1993
- Heywood, J. B. Internal Combustion Engine Fundamentals McGraw-Hill, Inc. 1988
- Dec, J. E. Espey, C. “Ignition and Early Soot Formation in a DI Diesel Engine using Multiple 2-D Imaging Diagnostics,” SAE Paper 950456 1995
- Patterson, M. A. Kong, S.-C. Hampson, G. J. Reitz, R. D. “Modeling the Effects of Fuel Injection Characteristics on Diesel Engine Soot and NOx Emissions” SAE Paper 940523 1994
- Kong, S.-C. Han, Z. Reitz, R. D. “The Development and Application of a Diesel Ignition and Combustion model for Multidimensional Engine Simulations” SAE Paper 950278 1995
- Han, Z. Reitz, R. D. “Turbulence Modeling of Internal Combustion Engines Using RNG k-ε Models,” Combust. Sci. and Tech. 106 4-6 267 1995
- Han, Z. Reitz, R. D. “A Temperature Wall Function Formulation for variable Density Turbulent Flows with Application to Engine Convective Heat Transfer Modeling” Int. Journal of Heat and Mass Transfer 1995
- Eckhause, J. E. Reitz, R. D. “Modeling Heat Transfer to Impinging Fuel Sprays in Direct-Injection Engines,” Atomization and Sprays 5 213 242 1995
- Liu, Z. Reitz, R. D. “Modeling Fuel Spray Impingement and Heat Transfer Between Spray and Wall in D. I. Diesel Engines,” Numerical Heat Transfer, Part A 28 1995
- Espey, C. Dec, J. E. “The Effect of TDC Temperature and Density on the Liquid-Phase Fuel Penetration in a D.I. Diesel Engine,” SAE Paper 952456 1995
- Han, Z. Uludogan, A. Hampson, G. Reitz, R. D. “Mechanism of Soot and NOx Emission Reduction using Multiple-Injection in a Diesel Engine,” SAE Paper 960633 1996