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Predicting the Effects of Air and Coolant Temperature, Deposits, Spark Timing and Speed on Knock in Spark Ignition Engines
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Abstract
The prediction of knock onset in spark-ignition engines requires a chemical model for the autoignition of the hydrocarbon fuel-air mixture, and a description of the unburned end-gas thermal state. Previous studies have shown that a reduced chemistry model developed by Keck et al. adequately predicts the initiation of autoignition. However, the combined effects of heat transfer and compression on the state of the end gas have not been thoroughly investigated. The importance of end-gas heat transfer was studied with the objective of improving the ability of our knock model to predict knock onset over a wide range of engine conditions. This was achieved through changing the thermal environment of the end gas by either varying the inlet air temperature or the coolant temperature.
Results show that there is significant heating of the in-cylinder charge during intake and a substantial part of the compression process. The effects of deposits on the combustion chamber walls in promoting knock were also investigated. Their primary effect is a thermal one: since the outer surface temperature of the deposits is hotter than that of the clean engine walls, greater bulk gas heating occurs. However, our results suggest that active species in the end gas carried over from preceding cycles may play a more important role in enhancing knock when deposits are present. Finally, initial work in developing a knock prediction methodology for investigating the audible knock limit of an engine was undertaken. A comparison of the audible knock predictions with the experimental limits as a function of speed is discussed.
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Brussovansky, S., Heywood, J., and Keck, J., "Predicting the Effects of Air and Coolant Temperature, Deposits, Spark Timing and Speed on Knock in Spark Ignition Engines," SAE Technical Paper 922324, 1992, https://doi.org/10.4271/922324.Also In
References
- Heywood, J.B. Internal Combustion Engine Fundamentals McGraw-Hill Book Co. 1988
- Hu, Haoran Keck, James “Autoignition of Adiabatically Compressed Gas Mixtures,” SAE paper 872210 SAE Trans. 96 International Fuels and Lubricants Meeting Toronto, Ontario, Canada November 2-5 1987
- Chun, K.M. “Characterization of Knock and Prediction of its Onset in a Spark-Ignition Engine,” Department of Mechanical Engineering, MIT 1988
- Cowart, J.S. Keck, J.C. Heywood, J.B. Westbrook, C.K. Pitz, W.J. “Comparison of Engine Knock Predictions Using a Fully-Detailed and a Reduced Chemical Kinetic Mechanism,” Western States Section of the Combustion Institute Livermore, CA October 23-24 1989
- Chun, K.M. Heywood, J.B. Keck, J.C. “Prediction of Knock Occurrence in a Spark Ignition Engine,” Proceedings of the 22nd Symposium (International) on Combustion The Combustion Institute 455 463 1988
- Cowart, Jim S. “Predicting Knock Onset in a Spark Ignition Engine,” Department of Mechanical Engineering, MIT 1990
- König, G. Maly, R.R. Bradley, D. Lau, A.K.C. Sheppard, C.G.W. “Role of Exothermic Centers on Knock Initiation and Knock Damage,” SAE paper 902136 International Fuels and Lubricants Meeting and Exposition Tulsa, Oklahoma October 22-25 1990
- König, G. Sheppard, C.G.W. “End Gas Autoignition and Knock in a Spark Ignition Engine,” SAE paper 902135 International Fuels and Lubricants Meeting and Exposition Tulsa, Oklahoma October 22-25 1990
- Valtadoros, Tassos H. “Fuel Additive Effects on Deposit Buildup and Knock in a Spark Ignition Engine,” Department of Mechanical Engineering, MIT 1990
- Keck, J. C. “Turbulent Flame Structure and Speed in Spark Ignition Engines,” 19th Symposium (International) on Combustion 1451 1987
- Zur Loye, A. D. Braces, F. V. “Two-Dimensional Visualization of Premixed-Charge Flame Structure in an IC Engine,” SAE paper 870454 1987
- Fox, Jonathan W. “Effects of Fuel Injection Strategy on HC Emissions During SI Engine Start-Up,” Department of Mechanical Engineering, MIT 1992
- Galliot F. Cheng W.K. Cheng C-O Sztenderowicz M. Heywood J. B. Collings N. “In-Cylinder Measurements of Residual Gas Concentration in a Spark Ignition Engine,” SAE paper 900485 The Society of Automotive Engineers 1990
- Haghgooie, M. “Effects of Fuel Octane Number on Knock Characteristics of a Single Cylinder Engine,” SAE paper 902134 1990
- Poulos, Stephen G. “The Effect of Combustion Chamber Geometry on S.I. Engine Combustion Rates-A Modeling Study,” SAE paper 830334 International Congress and Exposition Detroit, Michigan February 28 March 4 1983
- Park, P. Keck, J. C. “Rapid Compression Machine Measurements of Ignition Delays for Primary Reference Fuels,” SAE paper 900027 1990
- Reynolds, Wm. C. Stanjan chemical equilibrium solver Stanford, CA 1987